How do expectations modulate perception?
1Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany; 2Department of Psychiatry and Psychotherapy, Medical Center, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany; 3Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany; 4INSERM U1114, Cognitive Neuropsychology and Pathophysiology of Schizophrenia, University of Strasbourg, France; 5Institute for Frontier Areas of Psychology and Mental Health Freiburg, Freiburg im Breisgau, Germany
The information available to our senses is noisy, incomplete and often ambiguous. Our perceptual systems weight this information with perceptual memory concepts to construct stable and reliable percepts and to predict the immediate perceptual future. In the present study, we investigated whether predicting the future alters perceptual processing of the present.
We presented three repetitions of stimulus pairs consisting of ambiguous stimuli S1 followed by either ambiguous (Condition 1) or disambiguated stimulus variants S2 (Condition 2). Participants indicated their S1 percepts and compared S2- with S1-percepts. For each stimulus pair, the ERPs to the ambiguous S1 with an ambiguous future S2 were compared to an ambiguous S1 with a disambiguated future S2.
We found larger amplitudes of two ERPs to S1 from the first stimulus pair, compared to the other two pairs. Further, we found a trend for larger S1 ERP amplitudes when S2 was predicted to be unambiguous compared to predictions of an ambiguous S2. This effect was largest for the third stimulus pair.
The present results indicate that predicting the future affects perceptual processing of the present. However, some regularity within the immediate perceptual history seems to be a necessary precondition for both efficient perceptual processing and predicting.
Origins of expectation signals – a perfusion MRI study on visual repetition probability
Royal Holloway University of London, United Kingdom
Selectivity in the visual system is commonly investigated using fMRI repetition suppression (RS) paradigms as feature-selective BOLD signals are suppressed following feature repetition. However, RS magnitude for face stimuli varies depending on the probability of repetition – a phenomenon known as expectation signals (ES) (Summerfield et al. 2008). Unlike RS, however, ES are not apparent in fMRI when attention is diverted (Larsson and Smith, 2012) or in electro-physiological recordings (e.g. Vinken et al. 2018). Critically, hemodynamic events can occur without neural activity (Sirotin and Das, 2009), and thus ES could have hemodynamic rather than neural origins. Therefore, we replicated the original ES paradigm using arterial spin labelling (ASL) to simultaneously measure cerebral blood flow (CBF) and BOLD.
We find (N=15) evidence of ES in CBF and cerebral metabolic rate of oxygen (CMRO2) estimates. These estimates seem to transition from RS in early visual areas (V1/V2) to interaction effects (RS*ES) in higher visual areas (V3 and FFA/OFA). BOLD data show interaction effects in FFA/OFA, replicating previous findings. We demonstrate evidence for expectation dependent differences in neurovascular-coupling, and these effects vary as a function of visual hierarchy. This has important consequences for previous interpretations of ES based on BOLD alone.
Top-down control of Gestalt motion perception
1KU Leuven, Belgium; 2Universidade Federal do Rio Grande do Sul, Brazil
We investigated the time course of expectation effects on visual processing of coherent motion. We presented sequences of 10 random-dot-kinematograms (RDKs) with variable levels of coherent motion, while recording participants’ EEG. One RDK in the sequence (the target) was followed by an auditory post-cue. Participants were requested to rate the coherence level of the cued RDK target. Expectation was manipulated by the position of the post-cue in the sequence, so that the probability of the cue following an RDK would increase as the presentation sequence progressed. Behavioral results showed better discrimination of extreme than intermediate degrees of coherent motion. We obtained event-related potentials (ERPs) time-locked to RDK onsets, showing that with increasing expectation, amplitude of the ERP component N1 increased, but not that of the P1. Crucially, we found no interaction between the effects of expectation and motion coherence for P1, whereas we observed this interaction for N1. Additionally, while the P1 amplitude decreased with increasing coherence levels, the N1 amplitude was largest at the intermediary coherence levels. We concluded that expectation does not affect the early processing stage of motion coherence but influences motion perception at the later stages.
Selection history’s effect on visual attention persists after retraining and across multiple sessions
Philipps-Universität Marburg, Germany
In complex visual scenes, selective attention relies on efficient prioritisation of important objects. Recent work has shown that selection history is a critical component in the determination of processing priorities. In this study, we investigate how changes in selection history across multiple sessions can affect attentional orienting. 39 participants performed a categorisation task where they learnt to attend to either shapes or colours while EEG was recorded. This was interleaved by an independent search task where all participants identified the orientation of a line embedded within a shape singleton. Results on day one corroborate previous findings that if a coloured distractor is present during the search task, it causes greater interference for individuals who have learnt to categorise colours. On day two, half of the participants switched categorisation assignment. By day three, participants with experience of shape categorisation showed enhanced selection of the shape target. Participants who switched categorisation assignment showed impaired suppression of the colour distractor, and this is especially true for those who had started with colour categorisation on day one. This suggests that the influence of selection history is persistent across multiple days, even in the face of training which directly counteracts its effects.
Real-world structure facilitates object integration during multiple object processing
Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
Much of what we know about object recognition arises from the study of isolated objects. In the real world, however, we commonly encounter groups of contextually-related objects (e.g., teapot, cup, saucer), often in highly predictable spatial configurations (e.g., teacup above saucer, never the reverse). How does the visual processing of contemporaneous objects differ as a function of their contextual and spatial relatedness? To answer this, we recorded scalp EEG while participants (N=37) viewed a rapid stream of object pairs presented at a periodic rate of 2.5Hz. Where most pairs contained contextually-associated objects (e.g., table + lamp: Object Match), every fourth pair contained non-associated objects (e.g., egg + lamp: Object Mismatch). We observed a differential neural response to Mismatch vs. Match pairs (reflected at 2.5Hz/4 = 0.625Hz) over occipitotemporal electrodes, indicating that observers integrated object information even when performing an unrelated behavioural task (detect handbags/phones). Crucially, this integration index was larger when the image stream consisted of typically-configured pairs (e.g., lamp above table) rather than atypically-configured pairs (e.g., lamp below table). No such interaction was observed when inverting the display to account for low-level effects. These results indicate that both semantic and spatial relatedness influence visual object processing.
The generalizability of visual statistical learning: A case study in perceived real-world size
University of Szeged, Hungary
Past research has shown that the visual system automatically learns the transition probabilities between successive stimuli, resulting in more efficient processing of stimuli that can be predicted. In order to maintain tight experimental control, this work has typically required observers to make extremely simple judgments about the features of abstract stimuli. An important open question is whether visual representations of these temporal regularities are also leveraged toward performing more “real-world” tasks on naturalistic stimuli. Here, as a case study, we ran three experiments investigating the influence of statistical learning on real-world size perception. Observers viewed sequences of object images and made judgments about their real-world sizes (indicating whether the object could or could not fit inside a shoebox). Unbeknownst to observers, the sequences were manipulated such that some items reliably followed others. Although no observer reported noticing these statistical patterns, the temporal structure strongly improved their performance (evidenced by both reaction time and accuracy measures). We conclude that statistical learning forms a core part of how we represent visual objects, with general benefits extending to far more ecologically valid tasks than are usually studied.
The influence of context on behavioural and BOLD responses to low contrast information
University of Glasgow, United Kingdom
The brain uses contextual information to form predictions about and make sense of the visual world, especially when input is ambiguous or degraded. We have investigated the influence of context on the processing of low contrast visual information.
We displayed the bottom right corner of a visual scene (our target region) at low contrast (around threshold level) and manipulated the consistency of the remaining part of the image (the surround) with the target region. Psychophysically, we found that consistency between the surround and target influences the ability to identify low contrast information without affecting detection. Consistent surround and target improves performance whereas inconsistency between these regions hinders performance; indicating that the congruency of top-down predictions influences the processing of bottom-up information on a behavioural level.
In an fMRI experiment using the same paradigm, we found differences in the BOLD response between consistent and inconsistent conditions within the region of V1 corresponding to the target region. For low contrast stimulation in the target region the BOLD response was amplified if the high contrast surround was consistent. This could provide support for theories such as apical amplification and coherent infomax.
The Development the Light Source Bias in Shape-from-Shading
Bangor University, United Kingdom
Objects that are lighter at the top usually appear convex due to an implicit assumption that light originates from above. This percept is stronger when the light source originates from the above-left, which may suggest a right hemisphere dominance in shape-from-shading. This leftward bias is consistently observed in Western adults who read from left-to-right. In right-to-left reading populations, however, the bias is more variable; at times presenting as a diminished leftward bias, or sometimes as a strong rightward bias. To understand the contribution of cultural factors, such as habitual scanning direction, to the development of the light source assumption, we tested children in Wales and Israel on a visual search task of shaded spheres at different stages in reading acquisition. We expected all pre-literate children to exhibit a leftward bias, detecting oddball circles with a shading pattern consistent with light coming from the above left, faster than other orientations. We predicted rightward shifts in Israeli children as reading fluency increased. This might indicate that the leftward bias is a developmental default that can be modified by cultural factors. We will discuss differences between Welsh and Israeli children and implications for the lateralisation hypothesis in shape-from-shading.
An inversion effect in lightness perception: Light-from-above prior changes perceived lightness according to a pictorial orientation cue
1School of Human Sciences, Osaka University; 2Japan Society for the Promotion of Science
Kobayashi and Morikawa (2018, ECVP) demonstrated that upward-facing surfaces are perceived to be darker than downward-facing ones using stereoscopic stimuli. This shows the light-from-above prior’s role in lightness perception. Here, we created a non-stereoscopic image which can show surface orientation’s effect on lightness. This image depicts a simple gray surface. By inverting the whole image, the depicted surface’s orientation can be perceived as upward or downward. Even though the image’s two-dimensional and three-dimensional structures are identical, the inversion changes the surface’s apparent lightness. This was proved by Experiment 1 in which the participants performed a luminance adjustment task. In Experiment 2, novel participants performed the same adjustment task for the surface images at various angles (12 angle conditions in steps of 30 degrees including directly upward and downward). Perceived luminance levels as a function of the surface’s angle formed a U-shape, which was highest for downward-facing surface (angle = 0) and lowest for upward-facing one (angle = 180). Those for oblique angle conditions (angle = 30 to 150 and 210 to 330) lay between these two data points. The role of high-level processing for lightness perception is discussed.
Incongruent conceptual lighting enhances uncooperative and unassertive conflict-handling style
1Technische Universität Kaiserslautern, Germany; 2Duale Hochschule Baden-Württemberg Mannheim, Germany
Although it appears that we spend our entire day in white light, yet there are subtle variations in color temperature. More often than not, work environments have fluorescent tube-lights with neutral or cold color temperatures (above 3500K) while private spaces such as bedrooms/living-rooms utilize warm lights with lower color temperature (below 3000K). This may lead to a mental representation (concept) of lighting-space congruency. Interpersonal disagreements can happen anywhere. We investigated the influence of match between real and conceptual lighting on conflict-handling styles in different scenarios.
Experimental factors in a between-subject-design were lighting (warm~2500K; cold~3800K at constant illuminance level of 450lx) and imagined conflict situations (work-space: conflict with fellow student over unprepared upcoming presentation; private-space: conflict with landlord over apartment-related repairs). Thomas Kilmann Instrument was used to evaluate characteristics of different conflict-handling styles based on their position on the cooperativeness/assertiveness axes, namely, avoiding, competing, compromising, collaborating, or accommodating. Data from 68 participants show that incongruent-conceptual lighting significantly enhances the “avoiding” style (p<.002) compared to congruent-conceptual lighting in the experimental space. Thus, the combination of uncooperative and unassertive behavior is more susceptible to lighting-space incongruency compared to styles that are more positive on either or both of the cooperativeness/assertiveness axes.
Specific visual features of a novel tool specify different physics priors
Princeton University, United States of America
When manipulating a new tool, humans show different movement kinematics depending on whether the inner mechanics are visible or not. Although the visual features of the tool clearly must inform the selection of an appropriate model for the novel tool, there has been little investigation into how different visual parameters specify different internal models or, more generally, a physics prior. As a first step toward understanding this phenomenon, we had participants view a collision between a projectile and a target object (e.g. a tool), and then asked to predict the target’s future motion trajectory generated by the collision. When the target was viewed in isolation (noMT condition), observers relied quite accurately on Newtonian laws of mechanics for point masses. On the contrary, when the target was connected to a physical system (MT condition), participants exhibited a different physics prior. The accuracy of the MT-induced prior mainly decreased with the system’s complexity, while its precision varied along several dimensions, including the system’s initial state and the scene’s spatial and temporal statistics. The results confirm previous evidence that mechanical transparency affects how humans internally represent the functioning of tools, by exposing visual features that favor the selection of specific physics priors.
Food deprivation leads to bias along the perceived size of food-related stimuli
Department of Psychology, Ben-Gurion University of the Negev
Exposure to food-related stimuli leads to a set of biological, emotional and cognitive responses. Such responses are even more pronounced following food-deprivation. Related research showed that even a short period of food-deprivation leads to increased perceptual precision to detect changes in food portion-size.It is unclear,however, whether food-deprivation leads to systematic bias along the perceived food portion-size. Previous research led to inconclusive results, probably due to large variability across the experimental methods and the types of stimuli used. Here, we used a set of basic psychophysical tools, tailored to the field of food perception, to study the effect of food-deprivation on bias in food-size perception. In three experiments, food-deprived and non-deprived participants were asked to compare a series of food and non-food visual stimuli along their size. We calculated Point-of-Subjective-Equality (PSE) to measure the potential effect of food-derivation on the relative perception of size of food and non-food stimuli.In all experiments and for all stimulus pairs, results showed that food-deprivation led to a consistent bias in food-size perception. This bias was expressed by a relative shift along the perceived size of food-related stimuli which were perceived as bigger by food-deprived participants. This highlights the role of motivational factors in size-perception of motivationally-relevant objects.
The effect of aging on the eccentricity dependency of orientation anisotropy of perceptual surround suppression of contrast detection (SSCD)
University of Melbourne, Australia
Orientation anisotropies of perceptual surround suppression of contrast detection (SSCD) are present in young adults. Specifically, at 6ᵒ eccentricity, suppression is increased for horizontal stimuli, whereas at 15ᵒ, suppression is stronger for radially oriented stimuli. This reflects a link between SSCD and visual field retinotopy. Numerous studies have demonstrated that healthy aging alters features of surround suppression, however those studies have mostly involved foveal testing. Here we measure perceptual SSCD in the parafoveal region, in addition to the eccentricity dependency of orientation anisotropy.
Nineteen younger (mean age: 24.4, 18-32 years) and 19 older (mean age: 66.8, 60-72 years) adults participated. Contrast detection thresholds were estimated for horizontal, vertical, radial and tangential centre targets with parallel and orthogonal surrounding annuli. Nasal, inferior and infero-temporal visual field locations at 6ᵒ and 15ᵒ were tested. We find SSCD is stronger for older adults compared to younger adults at both 6ᵒ [t35=-2.243, p<0.05] and 15ᵒ [t35= -2.062, p<0.05]. Orientation anisotropy of surround suppression changed from a horizontal bias to a radial bias moving from 6ᵒ [F (1, 35) =5.5, p<0.05] to 15ᵒ [F (1, 35) =15, p<0.001] in older groups indicating similar eccentricity dependency of orientation biases of SSCD in both age groups.
Changes in optic flow parsing across the adult lifespan
1University of Manchester, United Kingdom; 2Cardiff University, United Kingdom
Older observers exhibit both local and global motion processing impairments. Here we investigate changes with age in optic flow parsing (FP) – a neural mechanism that acts to subtract out global motion arising due to self-movement (optic flow) so that scene-relative object movement can be recovered. We assessed different aspects of FP in two tasks (N=30, age range: 20-76). Task 1 measured the deflection in perceived trajectory of a probe presented in the opposite hemifield to a 2D expanding radial flow field, providing a direct estimate of the magnitude of subtracted optic flow (FP-gain). Task 2 measured direction discrimination thresholds for a horizontally moving probe in a field of 3D background objects across two conditions: i) no background movement; ii) background movement consistent with forwards observer movement. Smaller differences in thresholds between conditions signify better FP performance (FP-perf). We found strong evidence for a positive correlation between age and FP-gain (r=0.550, B10=25.636), suggesting increased optic flow subtraction with age. However, there was evidence for no correlation between age and FP-perf (r=0.136, B10=0.290). These data suggest that recovery of scene-relative object movement is functionally critical and the flow parsing mechanism adapts with age to preserve performance.
Age effects on visual search: contributions of bottom-up and top-down processes
1Experimental Psychology, Justus-Liebig-Universität Gießen; 2Cognitive Neuroscience of Perception & Action, Philipps-Universität Marburg
Visual search becomes slower and less accurate with increasing age. However, the contribution of bottom-up and top-down processes to these age effects has remained elusive. Declining sensory resources as well as cognitive control capacities could both play a critical role. We used an additional singleton paradigm to investigate age-specific vulnerabilities. A total of 19 younger adults (21-36 yrs.) and 21 older adults (62-74 yrs.) participated in our study. We measured the effect of a color singleton distractor during search for a shape target. Top-down control putatively inhibits stimulus-driven attentional capture. In all participants, we assessed individual sensory and cognitive control resources. Our data corroborated pronounced age effects on visual search performance. Older adults showed higher response times and lower accuracy. In addition, we observed robust distractor effects of the salient additional singleton that were consistent across experimental blocks. Notably, attentional capture was found to be similar in younger and older adults, suggesting retained top-down control in visual search. Individual differences in distractor effects across age groups moreover were predicted by sensory parameters, not by cognitive control measures. Our findings delineate bottom-up age effects on visual search from cognitive processes and qualify the modulation of attentional capture by top-down control.
Age-related effects of a monocular head-worn-display on the performance in a Lane Change Task
Leibniz Research Centre for Working Environment and Human Factors, Germany
Monocular head-worn-displays (HWD) are becoming increasingly popular not only in entertainment industry but also in actual workplace scenarios. However, several studies reported negative behavioral effects related to HWD. In the present study, we asked younger (19-30) and older participants (56-69) to perform a lane-change task in a driving simulator. Neutral or valid preparation cues were presented via HWD or simulator-screen, while uninformative distractor stimuli were in some trials presented simultaneously on the other device. Results showed that steering movements were initiated faster when task-relevant preparation cues appeared on the HWD and also when no distractor stimuli were presented. While this was true for both age-groups, younger participants responded generally faster. With regard to observed error rates (i.e. anticipations and erroneous lane changes), age-related differences were more complex. Overall, younger participants committed only few errors and error rates were not modulated by distractors or devices. Older participants committed more errors and performance was worst when neutral cues were presented via HWD. Taken together, results indicate a straightforward relationship between task-performance and the use of HWD, which is further modulated by age. While response speed using HWD was not affected by age, accuracy decreased with age, especially when uninformative stimuli were presented.
Impact of Observer Age On Color Matching Accuracy and Variability
KU Leuven, Belgium
Color matching functions (CMFs) or cone fundamentals are the most fundamental aspects of color science and color perception. Over time, much work has been carried out to ascertain the accuracies of the CIE (International Commission on Illumination) standard CMFs, however without any definitive answer, especially for observers of different ages. Recent work indicates an undeniable discrepancy between visual metamers and those calculated using the standard CMFs or the age specific CMFs derived using the CIEOP06 model. To further characterize this issue and work towards a better model, color matching experiments will be performed with observers from different age-ranges. Matches will be made using primaries with different peak wavelengths to determine the wavelength regions most sensitive to generating matching inaccuracies. Visual matches will be compared to matches calculated using CMFs derived using the individual observer model of Asano (2016), which includes various other parameters affecting CMFs in addition to age. For different age ranges, accuracy and variability will be analyzed as a function of model parameters and primary peak wavelength to derive more appropriate CMFs. This paper reports on the results of a pilot study with two groups of observers with average ages of 25 and 73, respectively.
Age-related differences in the neural processing of momentum
1Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taiwan; 2Department of Psychology, National Taiwan University, Taiwan; 3Center for Artificial Intelligence and Advanced Robotics, National Taiwan University, Taiwan; 4Institute of Statistical Science, Academia Sinica, Taiwan; 5Graduate Institute of Biomedical Sciences, China Medical University, Taiwan
Greater prior experience increases the contribution of statistical regularity on neurocognitive processes. We evaluated whether older adults, who in principle have more experience and exposure to different types of visual motion, would have stronger representations of momentum than younger adults. In a functional magnetic resonance imaging (fMRI) experiment, 24 younger (mean (SD) age = 22.79 (2.48) year-old) and 27 older (mean (SD) age = 65.78 (3.07) year-old) adults viewed sequences of sports-related actions consisting of quartets of picture stimuli. Quartets included regular (smooth actions), irregular (scrambled actions), and control (scrambled pictures) conditions for which participants rated the degree of consistency of the actions. Compared with younger adults, older adults rated regular sequences as less consistent, and irregular and control sequences as more consistent. Moreover, older adults obtained higher neural responses in medial frontal areas when they watched regular and irregular sequences in contrast to the control sequences. These findings support more dominant perception of momentum in older than younger adults and implicate medial frontal neural computations in driving this age-related cognitive difference.
Age-specific interferences between oculomotor and postural control
Justus Liebig University Giessen, Germany
Variation of postural stability increases with age and represents a major risk factor for falls. Although postural control is considered to be primarily an automatic process, stability can be modulated by secondary tasks. In particular, saccadic eye movements have been shown to reduce postural sway, but this beneficial effect critically depends on cognitive task demands. We investigated age effects on interferences between oculomotor and postural control. We measured postural sway under a fixation condition and saccade conditions involving specific cognitive demands, i.e. prosaccades and antisaccades. Sway measures were evaluated for two standing positions. A total of 24 younger adults (19-33 yrs) and 24 older adults (60-78 yrs) participated in our study. Older adults overall showed more pronounced sway and were more challenged by standing position demands. However, we observed similar beneficial effects of saccades across both age groups. Furthermore, our data supported that postural sway during saccades is increased if cognitive demands are enhanced. Notably, younger adults showed this pattern across both standing conditions, but for older adults it was degraded in the more challenging standing position. Our findings suggest robust stabilization of postural control by saccades. Modulation of sway by cognitive demands of saccades is attenuated with increasing age.
No country for old men? Reducing ageism bias through virtual reality embodiment
University of Milano Bicocca, Italy
Ageism is a negative attitude toward aging and elderly people. Many studies have investigated the effects of ageist attitudes and age stereotypes on the behaviour of others toward older persons and the self-related beliefs and behaviour of older adults themselves. By making participants embodying bodies of the same age and older, we aimed to induce the illusion of ownership for the virtual body and tested whether we could reduce negative implicit bias toward elderly people exclusively in the older body condition. We used a within group design including 24 adults participants. They completed 4 conditions by watching videos in virtual reality. Through a visuo-tactile synchrony stimulation between real and virtual condition we elicited an illusion of body ownership. Participants looked at their “virtual” arm while they were touched by the same wooden stick seen in the video, every second for two minutes. After each condition we measured the implicit attitudes toward elderly through an IAT paradigm. Results suggest a decrease of negative attitudes toward elderly people in adult population after the older body illusion. Future directions aim to replicate the study in an elderly sample in order to investigate how they perceive their own aging process.
Investigating Consequences of Age-related Hearing Loss on Attention and Executive Control
1Center for Mind/Brain Sciences (CIMeC), University of Trento, Italy; 2Department of Psychology and Cognitive Science, University of Trento, Italy; 3Centre de Recherche en Neuroscience de Lyon (CRNL), France; 4HNT Department, "Santa Maria del Carmine" Hospital, Rovereto, Italy; 5School of Psychology, University of Birmingham, UK
Recent proposals suggest that age-related hearing loss (ARHL) may be a possible risk factor for cognitive decline in older adults. The resulting poor speech recognition negatively impacts on cognitive, social and emotional functioning and relates to Alzheimer’s disease. However, little is known about the consequences of presbycusis on other non-linguistic domains of cognition. The aim of this study was to investigate the role of ARHL on covert orienting of attention, selective attention and executive control. We compared older adults with and without mild hearing loss (26-40 dB) performing a spatial cueing task with uninformative central cues (gaze vs. arrow), as well as a flanker task and a neuropsychological assessment of attention. In both groups, comparable gaze- and arrow-cueing effects were found on reaction time (RT), as well as similar flanker interference effects. Notably, hearing impaired individuals showed reduced foreperiod effect on spatial cueing of attention and tended to perform worse in the Montreal Cognitive Assessment (MoCA). This work indicates that attention orienting and response inhibition appear to be preserved following mild hearing loss, even if some specific aspects, associated with higher level voluntary behaviors, seem to be more deteriorated in older adults with mild ARHL.
Seeing a sound-producing event modulates the amplitude of the initial auditory evoked response
UNSW Sydney, Australia
An auditory event is often accompanied by characteristic visual information. For example, the sound level produced by a vigorous handclap may be related to the speed of hands as they move toward collision. Here, we tested the hypothesis that visual information about the intensity of auditory signals are capable of altering the subsequent neurophysiological response to auditory stimulation. To do this we used electroencephalography (EEG) to measure the response of the human brain (n=28) to the audiovisual delivery of handclaps. Depictions of a weak handclap were accompanied by auditory handclaps at low (65dB) and intermediate (72.5 dB) sound levels, whereas depictions of a vigorous handclap were accompanied by auditory handclaps at intermediate (72.5dB) and high (80dB) sound levels. The dependent variable was the amplitude of the initial negative component (N1) of the auditory evoked potential. We find that identical clap sounds (intermediate level; 72.5 dB) elicited significantly lower N1 amplitudes when paired with a video of a weak clap, compared to when paired with a video of a vigorous clap. Thus, this study provides evidence that the neural evoked response to an auditory event results from the combination of visual information about sound source intensity with incoming auditory input.
Mutual complete transfers between visual and auditory temporal interval learning support a central clock in sub-second temporal processing
Psychology, McGovern Brain Institute, and Center for Life Sciences, Peking University, Beijing
Perceptual learning of sub-second temporal interval discrimination (TID) shows asymmetric partial transfer from more precise auditory to coarser visual modalities, but not vice versa. These findings are interpreted as distributed, rather than central, temporal processing. We studied whether the modality specificity could be eliminated with double training, a technique developed in visual perceptual learning. We first replicated the null transfer from visual to auditory TID learning, and partial transfer from auditory to visual TID learning, with two Gabors or brief tones with a 100-ms inter-stimulus interval. However, visual TID learning, when paired with training of auditory frequency discrimination at the same 100-ms interval, transferred to auditory TID, as much as through direct auditory TID training. Similarly, auditory TID learning, when paired with training of visual contrast discrimination at a 100-ms interval, improved visual TID, as much as through direct visual TID training. Control experiments revealed no significant impacts of practicing auditory frequency discrimination or visual contrast discrimination alone on TID performance. Additional double training also enabled complete transfer of auditory TID learning from 100 to 200 ms. These results suggest a central clock for sub-second temporal processing, with its actual precision decided by peripheral modalities.
Modulation of behavioral and electrophysiological responses to visual targets by the reward value of co-occurring auditory or visual cues
1European Neuroscience Institute, Göttingen, Germany; 2Leibniz Science Campus Primate Cognition, University of Göttingen, Göttingen, Germany
Previous research has shown that valuable cues from visual (Bayer et al., 2017) as well as from auditory modality (Pooresmaeili et al., 2014) influence visual sensitivity. Here we compare the effects of visual and auditory valuable cues on perception, at the behavioral and electrophysiological levels.
The study employed a visual orientation discrimination task (peripheral Gabors, 9°). The Gabor appeared synchronously with either visual or auditory cues that were previously associated with reward value and were irrelevant to the task. By synchronous presentation, we expected that the reward value of the cues permeates the Gabor, thereby facilitating its perception.
We found that visual sensitivity (d’) and the amplitude of the early N1 component of the ERPs were modulated by both high-value auditory and visual cues. However, while auditory cues had positive modulation, high-value visual cues suppressed d’ and N1 amplitude. We did not find these differences in early P1 component where both auditory and visual high-value cues increased ERP amplitudes.
The results support a distinct mechanism for cross-modal versus within-modal modulation of perception by reward value. Whereas within-modal high-value cues compete for limited processing resources, valuable cross-modal cues can enhance sensory perception in another modality without interference.
Viewing hand motion elicits tickliness
1Tohoku University, Japan; 2Shokei Gakuin University, Japan
It is well known that self-produced and externally produced tactile stimuli are perceived differently. Here we examined that viewing hand motion could elicit tickle sensation without touching the participant’s knee. In our experiments, the participants were asked the degree of their subject feeling of tickle sensation after they watched self-produced or externally produced hand motion with or without touching their own knee. The results showed that externally produced visual stimuli was perceived as more ticklish than self-produced stimuli, and also visual hand motion presented near to the knee (within approximately 10 cm from the knee) induced tickle sensation. These finding suggest that visual induced tickle sensation is related to externally produced stimuli and occurs in a limited space surrounding body parts.
Olfactory stimulation modulates visual perception and brain activities in the visual cortex.
In many moments of our lives, our perceptual system integrates multi-sensory information, in a process called crossmodal perception. Most crossmodal phenomena are interpreted by spatial or/and temporal correspondences between a pair of unimodal features; however, some of them do not provide clear explanations of crossmodal relevance. One such phenomenon is the ‘fast lemon’ issue: When asked whether a lemon is ‘fast’ or ‘slow’, most people say ‘fast’. Does a lemon really induce ‘fast’ perception? Here, we conducted psychophysical and neuroimaging experiments in order to show the unique aspects of this strange crossmodal perceptual link. In the visual experiments with different olfactory stimulations (lemon, vanilla, or odour-free), in which participants were asked to report the speed of visual motion dots, faster or slower. As a result, we found that participants perceived the slower motion dots with a lemon smell, namely, our visual system counterintuitively made a connection between the lemon and ‘slow’. Additionally, brain activities in the visual cortex changed with the olfactory stimulations only when participants had difficulty making a decision. Our results demonstrate a new crossmodal perceptual link between vision and olfaction, and a characteristic feature of crossmodal perception with a pseudo-irrelevant stimulus.
Occipital cortex contributions to color sensations in grapheme-color synesthesia
University of Regensburg, Germany
Grapheme-color synesthetes have color sensations when viewing objectively achromatic letters or numbers. Building on previous results of increased visual cortex excitability in synesthetes, we investigated steady-state EEG responses within the visual cortex during repetitive grapheme presentations. Participants were presented with flickering arrays of color-inducing and non-color inducing graphemes and the steady state potential at the driving frequencies was analyzed. Color-inducing compared to non-color inducing graphemes produced larger occipital steady state responses in synesthetes. In addition, significant amplitude differences between grapheme conditions were associated with more vivid visual imagery in synesthetes, as obtained by self report (r = 0.58). No effects were observed in controls who saw matched sets of graphemes. The results suggest enhanced occipital cortex activity is linked to synesthetic mis-perceptions of color.
Spatiotemporal Integration or Feature Representation? Neuronal Coding of Dynamic Partial Shape Views in Macaque Anterior Body Patch.
Catholic University of Leuven, Belgium
Humans easily recognize objects even if only a small part of the object is available in every instant at the same retinal position. This requires a strong spatiotemporal integration of the shortly available visual features. Previous fMRI studies revealed that the lateral occipital complex plays an essential role in forming a whole shape percept. To investigate the neuronal mechanisms, we measured neuronal activity in the macaque anterior body patch, presenting animal silhouettes moving behind a narrow 0.5° horizontal or vertical slit in both directions.
Our goal was to test if the stimulus selectivity of static images is preserved under anorthoscopic presentation and additionally to investigate the strength of feature integration by presenting feature-preserved temporal randomized stimuli as control.
Single neurons showed diverse activity. At the population level, stimulus selectivity was preserved for the slit-views. We measured a significantly higher firing activity for the slit-views of original than for their randomized presentations. Using multivariate classification, we observed information transfer between vertical and horizontal presentations, but weaker than between directions of the same orientation. The generalization matrices had a strong diagonal temporal profile, which suggests that the neurons integrate slit information of their preferred features, but not encode the whole shape.
Object representations based upon shape circularity and local curvature identified in Lateral Occipital Cortex
1Department of Psychology, University of York, YO10 5DD; 2York Neuroimaging Centre, Univesity of York, YO10 5NY; 3York Biomedical Research Institute, University of York
Whilst curvature-based shape representations have been identified in Macaque V4, the homologue in humans is unclear. To examine human neural responses to curvature, we parametrically varied radial frequency patterns across orthogonal dimensions of amplitude and frequency, presenting them in a rapid event-related fMRI design. Responses to these stimuli were explored using multivoxel pattern analysis (MVPA) and representational similarity analysis (RSA), conducted in retinotopically-defined regions V1-V4, LO-1 and LO-2, plus the functionally-defined (objects > scrambled objects) Lateral Occipital Complex, split into LO and pFs.
We identified a frequency influence specific to LO1, and an amplitude influence that dominated in all Lateral Occipital regions (LO-1, LO-2, LO) which was likely capturing shape circularity. Further exploration then revealed an additional influence in these areas; that of local curvature. None of our metrics could reliably explain neural similarity in V4.
These results could explain human curvature hyper-acuity, and they hint that Lateral Occipital brain regions may be better homologues of Macaque V4, at least in term of curvature processing.
Temporo-parietal brain regions are involved in higher order object perception
1Centre of Neurology, Division of Neuropsychology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany; 2Department of Psychology, University of South Carolina, Columbia, USA; 3Department of Neurosurgery and Neuroscience, Baylor College of Medicine, Houston, Texas
Lesions to posterior temporo-parietal brain regions are associated with deficits in Gestalt perception, but also impairments in the processing of objects presented under demanding viewing conditions. Evidence from neuroimaging studies as well as lesion patterns observed in patients with object orientation agnosia suggest similar brain regions to be involved in Gestalt perception and processing of objects in atypical (‘non-canonical’) orientation. In an event-related fMRI design, we collected data of 20 healthy volunteers to systematically test whether temporo-parietal brain areas that are involved in Gestalt perception are also involved in the perception of objects presented in non-canonical orientations (compared to objects in canonical orientation). Using individual temporo-parietal ROIs, we found significantly higher activation during the processing of non-canonical objects compared to objects presented in a canonical orientation. These results suggest that temporo-parietal brain areas are not only involved in Gestalt perception but might serve a more general mechanism of complex object perception. Our results challenge a strict attribution of object processing to the ventral visual stream by suggesting dorsal contributions in more demanding viewing conditions.
Looking through our internal eye: internally directed attention impedes object identification
Radboud University, The Netherlands
The phenomenon of “seeing less” while attending internal representations is well-known among the general public. However, a direct comparison of internally versus externally directed attention has not yet been performed. In this study, we measured the effect of internal versus external attention on the recognition of objects in natural scenes. Perceptual performance was probed while participants directed attention either internally or externally using a dual-task design. An internal attention state was induced by having participants perform a visual working memory task, while an external attention state was induced by having participants monitor whether briefly presented images exhibited mirror symmetry. Importantly, retinal input was controlled for by using exactly the same stimuli in both tasks. Within each of the two dual tasks, half of the trials ended with the object recognition probe while the other half ended with a probe relevant to the respective task type - either a working memory probe or a question about the number of symmetrical images. Results showed that object recognition (d-prime) was worse during the internal compared to the external attention task. This study provides empirical evidence for the distinction between internal and external attention by showing that directing attention internally hinders naturalistic object recognition.
The role of object frequency in an “object decision task”
Scene Grammar Lab, Department of Psychology and Sports Sciences, Goethe Universität, Frankfurt am Main, Germany
Objects are found in the environment in a regular way: they appear frequently in some scenes and less frequently, or never, in others. Our cognitive system exploits these regularities to efficiently accomplish visual tasks. Typically, studies compared neural and behavioural response to objects intuitively defined as “consistent” or “inconsistent” within a scene. We tried to assess object frequency in a more systematic way, using Greene’s (2013) dataset of images with object labels, and computing the frequency of objects with regard to the whole dataset as well as to specific scene categories. We then tested the role of these measures – comparing them with human observers’ ratings and basic image properties - in predicting RTs during an “object decision task” where participants had to categorize objects as either real or fake, after being primed with a scene label. Our results suggest that neither the object frequency computed from the database, nor the rated object-scene consistency, seem to be relevant for the task, while the rated prototypicality as well as the saliency of the object image seem to modify RTs. We conclude that at least for this type of object decision task object frequency information is not behaviourally relevant.
Two types of ‘no’ response in object detection and basic-level categorization with fragmented object contours
1Doshisha University, Japan; 2University of Kaiserslautern, Germany; 3University of Leuven, Belgium
In this study, we investigated the different decision processes underlying yes/no responses in object detection and three categorization tasks (i.e., natural/artifactual, superordinate-level, and basic-level category). Images of fragmented object contours with different fragment types (mid-points and salient points) and fragment length (short and long) were briefly presented (150ms) at the centre of screen. Participants were asked to decide whether or not the depicted object belonged to a particular object category, indicated by specific questions presented before the image (i.e., ‘Object?’, ‘Natural?’, ‘Bird?’, and ‘Car?’). Gamma finite mixture modelling of the distributions of response times showed that the ‘no’ responses in detection and basic-level categorization were composed of two types of decisions (fast and slow), while the ‘yes’ responses in all tasks and the ‘no’ responses in the natural/artifactual and superordinate-level tasks did not. ANOVAs on response time and accuracy, on the other hand, indicated significant differences between the ‘no’ and ‘yes’ responses at difficult task (i.e. short fragment length). Therefore, ‘no’ responses at detection and basic-level categorization might involve two types of decisions: intuitive (i.e., fast but inaccurate) and accurate decision depending on received information for detection, fast and slow decision by speed of matching processing for basic-level categorization.
Effects of meridian-specific scaling on shape discrimination hyperacuity across the visual field
University of Plymouth, United Kingdom
Preference for contour shape perception was found for the lower visual field up to 10° when a uniform scaling was applied across the visual field (VF). In this study, we investigated contour shape perception across the VF up to 20° using meridian-specific scaling.
We measured modulation thresholds (N=4), expressed as the proportion of the radius, with a 2IFC Shape Discrimination Hyperacuity (SDH) task where sinusoidally modulated contours (radial frequency patterns) were discriminated from circles. Stimuli (baseline radius=0.8°) were size-scaled according to the cortical magnification factors for the left, right, upper and lower VF and presented on a calibrated CRT monitor at 5°, 10°, 15° and 20° across the horizontal and vertical meridians.
Performance in SDH task was constant between 5°-15° with higher thresholds at 20° in all parts of the VF, except for the lower VF where it was uniform up to 20°. In the lower VF, thresholds were lower than in other parts, however, these differences were statistically non-significant (F(2.17,38)=3.1, p=0.11). This could be caused by the non-specific variability in the dataset.
Meridian-specific scaling reduces the difference between central and peripheral performance and the magnitude of the lower VF preference for SDH.
Shape aftereffects are retinotopic and are explained by the local tilt aftereffect
The University of Western Australia, Australia
In this study we first confirm earlier findings that shape aftereffects in radial frequency (RF) patterns, patterns deformed from circular by a sinusoidal modulation of radius, can be accounted for by the systematic application of local tilt aftereffects around simple closed figures. Second, by using eye-tracking equipment to constrain the presentation of stimuli to five experimental subjects to periods of time when they were fixated on a stationary dot, we show that the effects of adaptation are only observed when the boundaries defining the shapes of adaptor and test stimuli are presented in retinotopic correspondence. Specifically, we demonstrate, using the method of constant stimuli in a single interval forced choice task, that circles are perceived as having no RF modulation after adaptation to concentric RF patterns with different radii or similarly sized RF patterns with centre separations that render them discrete in space. Large aftereffects were observed after adaptation to concentric RF patterns with the same radii. We conclude that adaptation to orientation selective filters of the primary visual cortex provides for a general mechanism of exaggerating the perceived difference between successively experienced similar figures when they are retinotopically coincident.
Effects of microsaccade on global processing of shape
University of Nottingham, United Kingdom
Global pooling mechanisms that integrate local form-information around an object are thought to underlie the sensitivity of the human visual system to subtle changes in shapes. Tasks demonstrating global integration are typically completed under conditions of steady fixation, however some research suggests that the percept of global structure can collapse under prolonged fixation. In this study, we investigate whether small ocular movements during steady fixation (microsaccades) influence global processing of shape. Participants were asked to discriminate between two peripherally presented closed-contour radial frequency patterns (created by the addition of sinusoidal modulation to the radius of a circle), while fixational eye-movements were recorded binocularly at 500Hz. Microsaccdes were detected using a velocity-based algorithm allowing trials to be sorted according to the relative timing of stimulus and microsaccade onset. Results indicate a general detrimental effect of microsaccades on task performance consistent with previous demonstrations of saccadic suppression. The presence of global pooling (indicated by a rapid improvement in threshold as additional cycles of modulation were added) appeared to be unaffected, suggesting its relative robustness to small fixational eye movements.
Form preferences depending on symmetry types and topological relations
1Laboratory for Perceptual and Cognitive Systems at the Faculty of Computing, University of Latvia, Latvia; 2Faculty of Business, Management and Economics, University of Latvia, Latvia
Although it is well documented that human perception is sensitive to reflection symmetry, less known are the impacts of other symmetry types and their topological relations.
In our study, preferences for different symmetries (e.g., translation, rotation) and basic topological relations (e.g., connectedness, overlap) were tested.
Two sets of online experiments were conducted: (1) a preference rating task based on 5pt Likert scale (n=99), and (2) a reaction time (RT) forced-choice task with two random options (n=91).
The results confirmed preferences for symmetry, however, to different degree in different symmetry types. In RT analysis, the most frequent choices correspond with the results from the rating task. Shapes with dihedral rotation symmetry are most preferred and have the shortest RTs. Less preferred are (a) asymmetric shapes and shapes (b) belonging to symmetry groups that include only one nontrivial isometric transformation and (c) with oblique symmetry axis. A significant (p=0.05) negative association (r=-0.443) between frequency of choice and RT can be observed. The longest RTs correspond to asymmetric shapes and shapes with glide reflection symmetry.
According to our results, also topological relations significantly contribute to form preferences – combinations are rated differently even in the same symmetry group if representing different topological relations.
Does microgravitation influence the optical apparatus of the eye?
1Russian Federation State Research Center Institute of Biomedical Problems, Russian Academy of Sciences, Russian Federation; 2Institute for Information Transmission Problems (Kharkevich Institute), Russian Academy of Sciences
The data available indicate that, after prolonged cosmic flights, some hypermetropic changes could be detected in the eyes of astronauts, perhaps as a result of weightlessness. It was the reason to perform pilot studies using a technique of dry immersion that creates the conditions of microgravitation imitating such effects of weightlessness as redistribution of the liquids in the body and decrease of proprioceptive afferent flows leading to decrease of sympathic tonus of the nervous system. In the framework of the Project “Immersion”, we investigated refraction and accommodation in subjects (aged 25-35 yr) immersed into special baths for 5 and 21 days (10 and 6 subjects, respectively). The measurements were accomplished by means of auto-refracto-keratometer Righton Speedy-i before the experiment, and 7 days after its end. The aim was to assess the stability of the accommodation regulatory mechanisms using the parameters of accommodation response and high-frequency microfluctuations. After 5 experimental days, a decrease of the accommodation response was found in 11 eyes, and in 7 of them – decrease of high-frequency microfluctuations. After 21 experimental days, in 3 from 6 subjects, the accommodative responses didn’t differ significantly from the initial values, indicating high adaptation capability during a given duration of artificial weightlessness.
Visual acuity charts: comparison study
1Institute for Information Transmission Problems (Kharkevich Institute), Russian Academy of Sciences, Russian Federation; 2Pirogov Russian National Research Medical University (RNRMU), Russian Federation
The aim of the study was to compare Lea-screener chart and new visual acuity charts: with wide-space design (IITP) and with proportional design (IITP-V) in view of repeatability.
42 subjects (11.1±0.2 years) with ophthalmopathology were divided in 2 groups: 15 - with optic nerve atrophy and retinopathy, 27 - with light amblyopia (median visual acuity - 0.1 (1.0 logMAR) and 0.9 (0.05 logMAR), correspondingly).
Best corrected visual acuity was assessed twice (test and retest) with three charts in random order, monocularly and binocularly, at viewing distance 4 m.
We compared test and retest data by Wilcoxon signed-rank test. In group 1, test and retest was significantly different for Lea chart (p=0.003), that means poor repeatability; for IITP and IITP-V charts no significant differences were found (p=0.611 and p=0.807). In group 2, no significant differences were found for all three charts (p=0.727 - Lea, p=0.340 - IITP, 0.974 - IITP-V).
Thus, according to our data, in group with worse visual acuity (with optic nerve atrophy and retinopathy) Lea-screener chart show worse repeatability than IITP and IITP-V chart. In group with better visual acuity (light amblyopia) all charts provided comparable results.
LogMAR is not a proper measure for visual acuity assessment
Institute for Information Transmission Problems (Kharkevich Institute), Russian Academy of Sciences, Russian Federation
Delusion concerning an advantage of using logMAR (logarithm of the Minimal Angle of Resolution) in visual acuity investigations originated four decades ago when several authoritative scientists claimed that it would be better to express the results in logMAR instead of Snellen ratio, decimal notation, critical spatial frequency, etc. The initiators mentioned that they could not adduce strong arguments in favor of this idea; their followers also failed to be persuasive. Nevertheless, many optometrists and psychophysicists appeared to be inspired and tried bringing logMAR into use. Indeed, it was realized that logarithmic scales were good for creating visual acuity test charts with a proportional design. However, some essential inconveniences emerged in the logMAR practical usage stimulated us to perform a metrological analysis and to overview clinical reports. The conclusions are: (1) logMAR can’t be considered as a correct measuring unit; (2) usage of logMAR doesn’t provide any advantages in data analysis; (3) in clinical calculations, negative logMAR values often lead to errors. In contrast, Snellen ratio, decimal notation, and critical spatial frequency are well suited to the requirements of metrology and consistent with human intuition. Actually, these three measures are equivalent since they are directly proportional to each other.
Assessing the status of visual cortex in macular disease
1Department of Psychology, University of York; 2York Teaching Hospital; 3York Neuroimaging Centre, University of York; 4Hull York Medical School, University of York; 5York Biomedical Research Institute, University of York
The current focus in ophthalmological research concerns physiological changes within the eye, aiming to treat eye disease and prevent further loss of vision. However, comparatively fewer studies assess the consequences of eye disease on visual cortex. Macular Degeneration (MD) embodies a collection of disorders causing a progressive loss of central vision. Cross-sectional studies have revealed structural changes in visual cortex in MD, but the rate of change is unknown. We acquired structural MRI data on 10 patients with different forms of MD and 18 age-matched controls over multiple time points in a ~2 year period, to explore the rate of change in cortical thickness within the occipital pole (OP) and calcarine sulcus (CS). Data were analysed using a linear mixed-effects model. Preliminary data show a significant reduction in grey matter in patients in the OP, and an accelerated rate of decline compared to controls. Whilst patients did have a significantly thinner CS, the rate of change did not differ between groups. Understanding the time course of changes may prove important for visual restoration; if visual cortex is no longer viable, the success of interventions aiming to restore functionally useful vision will be limited.
The study of the illusion of phosphenes in pupils with partial atrophy of the optic nerve and with amblyopia
1Institute for Information Transmission Problems, Russian academy of sciences, Russian Federation; 2Pirogov Russian National Research Medical University
The work is devoted to the study of the conditions of emergence of the illusion of phosphenes and assessment of its power in children with partial atrophy of the optic nerve (PAON) and children with amblyopia. 69 children of school age were divided into 3 groups: 1) 22 pupils with PAON; 2) 23 pupils with amblyopia; 3) 24 pupils of the control group. In the study we used the test images performed like variants of “scintillating grid” with disks (in the crosshairs of the grid) of different diameters. Test images were displayed on the computer screen. We found significant differences between the manifestations of the illusion of phosphenes in all three groups of subjects. In children with PAON there was a “shift” of the power of the illusion towards a larger diameter of the discs in comparison with the children of the control group and with the children of the amblyopic group. In amblyopic children we observed reducing of the power of the illusion in comparison with the children of the control group. We suppose that these differences may be related to larger receptive fields in children with PAON and to functional inhibition of visual perception in children with amblyopia.
Reduction of migraine episodes in meniere patients following chronic use of weak prismatic spectacles
1General Practitioner, Utermöhlen Foundation ( Balance & Orientation) The Netherlands; 2Birkbeck, University of London, United Kingdom
One non-invasive treatment of Ménière disease is the chronic use of Weak Asymmetric Base-in Prism spectacles (WABIPS), a method developed by Utermöhlen more than half a century ago. A recent report by Vente et al. evaluated this treatment in a cohort study of 580 unilateral patients. They found 97% subjective satisfaction and reduction of vertigo, and 57% reduced or stopped concomitant medication. The present paper reports the results of such weak prismatic spectacles on a subset of this group who also experienced migraine. Patients had to fulfill the criteria for unilateral Ménière disease according to the guidelines of the American Academy of Otolaryngology, Committee on Hearing and Equilibrium (a history of cochlear hearing loss, recurrent spontaneous, rotational vertigo attacks longer than 20 minutes) and the International Headache Society criteria for migraine (throbbing, unilateral headaches, photo and/or phonophobia, nausea, vomiting ), with or without aura. Three hundred and twenty five patients were thereby included in the present study. Patients had to use the prism lenses permanently over a twelve month period. After one year of WABIPS treatment, 43% of patients with Ménière disease and migraine experienced no migraine episodes (McNemar chisquare = 78, p<0.0001).
Quantified motion illusion strength does not correlate with daily visual discomfort in people with migraine
The University of Melbourne, Australia
In between migraine events, increased susceptibility to self-reported visual illusions induced by high contrast striped patterns has been used as an index of greater visual discomfort in people with migraine relative to controls. It is unclear how the mechanisms of visual illusion and visual discomfort are related. We quantified the strength of a contrast induced motion illusion (a variant of the Fraser-Wilcox illusion) with a two-alternative forced choice task in 36 (16 with aura, 20 without aura) people with migraine and 20 headache-free controls. The illusory motion stimulus was injected with additional physical motion. Participants indicated the perceived direction of stimulus rotation. The physical motion speed that counterbalanced the illusory motion was quantified as the motion illusion strength. Daily visual discomfort was self-reported via questionnaire. Relationships between motion illusion strength, contrast discrimination threshold, and motion sensitivity were also investigated. On average, people with migraine with aura reported greater visual discomfort compared to controls (p<0.05). Regardless of migraine status, motion illusion strength was negatively correlated with contrast discrimination threshold (r = -0.271, p = 0.04), but not with any other measurements. Self-reported visual discomfort did not relate to quantified perceptual motion illusion strength.
Simple reaction time to chromatic stimuli in patients with hypothyroidism
1Institute of Neurobiology, Bulgarian Academy of Sciences, Bulgaria; 2School of Biomedical Sciences, University of Ulster, UK; 3Department of Endocrinology, Medical University Sofia, Bulgaria
Hypothyroidism causes a slowing of all processes in the body, including the visual system and affects the opsin production and nerve myelination. Patients with hypothyroidism have prolonged reaction time (RT) for achromatic stimuli but RT for chromatic stimuli has not been studied. We measured simple RT for chromatic spots, 4 deg in diameter, presented at 20 deg in temporal retina in patients with hypothyroidism and age-matched control groups. We used three contrast levels, multiples of the detection threshold. The chromaticity of the stimuli varied from white to 90, 270, 0 and 180 deg in the isoluminant plane of DKL space, loosely called blue, yellow, red and green. The results showed that RT in patients was significantly longer than controls (p<0.001) under all conditions. The RT increase in the hypothyroid group was most pronounced for yellow stimuli, most notably at lower contrast ( 536 msec for patients vs 425 msec for controls, p<0.001). The RT increase was also contrast dependent for blue stimuli (p < 0.001).
These results indicate that, hypothyroidism affects the temporal response for all colours tested, but especially yellow and blue. The contrast dependence of the RT increase in hypothyroid patients requires further consideration.
The Absence of the Visual Looming Illusion in Non-Hearing People
1DIBRIS, University of Genoa; 2Italian Institute of Technology
Time perception is essential to interact with the environment and is strictly connected with attentional resources (e.g. more attention is paid to an event, more it appears to last longer). It has been shown that interval discrimination, in the milliseconds-to-seconds range, is sharpened by hearing, that also calibrates the other senses.Thus, an interesting question is what happens to the temporal perception of briefly displayed visual stimuli when the auditory information is absent as in deaf individuals. To answer this question, we tested a group of deaf and a group of normal hearing participants in a visual oddball-like paradigm. Participants had to discriminate the duration of a target presented as fourth in a sequence of five stimuli. In addition to changing the duration of the target, also the size gradually changed. Our results show that when the oddball encoded only temporal information (being static), deaf participants underestimated its duration. However, the time dilation normally elicited by looming oddballs – encoding both spatial and temporal information – was not experienced by deaf participants. This lack of time dilation suggests that, when hearing is not available, temporal perception is biased, but temporal accuracy can be linked to the properties of the stimuli themselves.
Increased reliance on vision during grasping in Carpal Tunnel Syndrome
1Bangor University, United Kingdom; 2Ysbyty Gwyenedd, Bangor, United Kingdom
Healthy grasping is characterized by predictive movements, and relies not only on vision but also proprioception and touch. The hand shapes to match object properties ‘in flight’, prior to object contact. Without visual feedback, the hand opens wider and moves slower, yet these compensatory changes are subtle, and skilful anticipatory control is maintained. Here, we investigate the kinematics of grasping with and without visual feedback in patients with Carpal Tunnel Syndrome (CTS), a peripheral neuropathy caused by chronic compression of the median nerve. Patients with CTS suffer from pain, paraesthesia, diminished touch sensitivity, and impaired fine motor skills. We hypothesized that due to impoverished somatosensory feedback CTS patients would show exaggerated compensatory changes when grasping without vision. Consistent with this hypothesis, CTS patients slowed their movements more than healthy controls when visual feedback was removed. Hand opening was not disproportionately affected by the removal of visual feedback in CTS, however, and anticipatory grip scaling was maintained. With vision available, CTS patients showed stereotypical grasp kinematics, indistinguishable from controls. Our results highlight the importance of both visual and non-visual signals in the skilful control of grasping, and suggest that CTS patients increase reliance on vision to compensate for impaired somatosensory inputs.
Weaker Non-Verbal Skills at Five Years of Age Predict Need for Long-Term Educational Support in Very Preterm Children
1Department of Psychology, University of Turku, Finland; 2Turku Institute for Advanced Studies (TIAS), University of Turku, Finland; 3Department of Pediatrics, University of Turku and Turku University Hospital, Finland; 4Children’s Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Finland
Difficulties in skills related to visual perception are common in prematurely born children. We report the predictive value of non-verbal functions at five years of age on the need for educational support at eleven years of age in very preterm children (birth weight ≤1500g and/or gestational age <32 weeks, n=141) without neurodevelopmental impairments. At five years of age neuropsychological functions were assessed with NEPSY II, and at eleven years of age data on educational support services was collected using a questionnaire. Overall, performance in NEPSY II subtests predicted well a need for later educational support. Poorer scores in those NEPSY II subtests that were related to visual memory, visuomotor and/or visual perception at five years of age were significantly associated with need for special education and/or studying on a grade below own age group at eleven years of age. These results highlight the clinical importance of psychological assessment at five years of age in the follow-up of very preterm children and the relevance of visual perceptual skills on other abilities. Early identification of impairments or risk for difficulties enables developmental support in order to strengthen skills and prevent the development of associated or secondary problems.
Unfamiliar face processing in Williams syndrome
University of East Anglia, United Kingdom
Researchers have suggested that atypical mechanisms may underpin the often reported strong face processing abilities in Williams syndrome (WS). Yet limited targeted research exists. Here, we investigate unfamiliar upright and inverted face-processing with a version of the ‘Telling Faces Together’ task (Jenkins et al., 2011) that requires participants to differentiate within-person variability (different images of the same person) from between-person variability (different images of different faces). Performance of 16 adults with WS (M=28.8years) was contrasted with typically developing (TD) adults (M=20.4years, N=23) and three TD child groups (6-7years, N=32; 8-9years, N=30; 10-11years, N=39). For upright faces, there was no significant difference in WS accuracy relative to the chronological age comparison group (p=0.53), but a pattern of superior performance to all child groups (p=0.042; p=0.078; p=0.079 respectively). By contrast, they showed a pattern of decreased performance for inverted faces relative to adults (p=.029), and two of the children’s groups (p=0.09; p=0.29; p=0.09). These results provide further support for strong face identity processing in WS, including direct evidence that this profile encompasses unfamiliar exemplars. Moreover, the dramatic drop in inverted performance suggests utilisation of specialised processing mechanisms tuned to the canonical orientation of faces, perhaps even more than in the typical population.
The reward value of emotional genuineness in Williams Syndrome
1Department of Psychological Sciences, Birkbeck College, University of London; 2Department of Psychology, University of East Anglia, Norwich, UK; 3Australian National University; 4University of Surrey, UK
Typical developing (TD) individuals are sensitive to the authenticity of emotional signals: capable of detecting subtle differences in facial expressions associated with being ‘genuine’ vs ‘posed’. It is not known whether this sensitivity is present in another group of atypically developing individuals that experience social difficulties, i.e. individuals with Williams syndrome (WS). This group is reported to show heightened social drive, speculatively linked to observed atypicalities in face processing. We used an economic key-pressing paradigm to measure the reward-values associated with viewing faces expressing genuine or posed emotions (anger, happiness, sadness) in 16 adults with WS, 103 TD adults (similar in chronological age) and 129 TD children (6-13years, similar range of cognitive ability). Results revealed elevated rewards for happy faces relative to angry and sad faces across all groups. TD children did not differentiate authenticity in their responses, TD adults showed a preference for genuine expressions across emotions, WS participants showed a selective preference for posed happy expressions. Subsequent emotion recognition checks revealed that WS participants experienced difficulties identifying/labelling sadness and anger. Like typical participants, individuals with WS find positive emotions more rewarding, and perhaps surprisingly, where they are sensitive to authenticity, they prefer posed (i.e., social) over genuine smiles.
The functional state of magnocellular and parvocellular visual pathways in depression
1Pavlov Institute of Physiology, Russian Federation; 2Pavlov First Saint Petersburg State Medical University, Russian Federation; 3St. Petersburg City Psychiatric Hospital №1, Russian Federation
The aim of this study was to examine the functional state of magnocellular and parvocellular visual pathways, and their interaction in depression. The magnocellular and parvocellular systems are differentially sensitive to spatial frequency. The magnocellular system is most sensitive to low spatial frequencies, the parvocellular system to high spatial frequencies. The study involved healthy participants and patients with depression. We measured visual contrast sensitivity thresholds in detection and comparison tasks (Gabor elements with spatial frequencies of 0.4, 3.6 and 17.8 cycles/degree were presented). We found that patients with depression are characterized by a decrease in contrast sensitivity in all ranges of spatial frequencies as compared with the mentally healthy. Thus, patients with depression demonstrate a decrease in sensitivity of the magnocellular and parvocellular systems. The problem of sensitivity of the magno- and parvocellular systems is not only theoretical but also of practical importance. The practical significance of this research lies in the development of methods of sensory rehabilitation. We propose to consider the functional state of magno- and parvosystems as a biomarker of psychotic condition.
This research was supported by the Russian Foundation for Basic Research (grants 18-013-01245).
Alcohol usage predicts holistic perception: A novel paradigm to explore addiction
1Loughborough University, United Kingdom; 2Richmond University, USA
Holistic perception is a special form of automatic and experience dependent processing that prioritises objects of interest through the visual system. We therefore speculated whether higher levels of alcohol consumption are associated with enhanced holistic perception for alcohol cues, and reduced holistic processing for non-rewarding items. In our first experiment, we confirmed this hypothesis by showing that increasing regular alcohol usage was associated with greater holistic perception of alcohol, but not non-alcohol, cues. We replicated this finding in a second experiment, but confirmed holistic perception was not predicted by experience with a specific drink, but rather general alcohol usage. In our final experiment when alcohol images were absent from the task, higher levels of regular alcohol use predicted decreased holistic perception for non-rewarding cues. Increasing alcohol consumption is therefore linked to inverse alterations in holistic perception for alcohol versus non-alcohol cues, with the latter’s effects context dependent. We hypothesise that such inverse relationships may be due to limited cortical resources becoming reutilised for alcohol cues at the expense of other stimuli. Future work is required to determine holistic perception’s role in maintaining addiction, its predictive value in successful abstinence, and its relationship with attentional biases.