David Alais

• Professor (Full) at The University of Sydney

Visual rivalry paradigms provide a powerful tool for probing the mechanisms of visual awareness and perceptual suppression. While the dynamics and determinants of perceptual switches in visual rivalry have been extensively studied and modeled, recent advances in experimental design - particularly those that quantify the depth and variability of per...

Spatial frequency is a fundamental feature in both visual and somatosensory perception, yet how these modalities integrate spatial frequency information remains unclear. This study investigates whether visuotactile spatial frequency perception follows the principles of Maximum Likelihood Estimation (MLE) and whether spatial proximity influences mul...

Working memory is the ability to maintain a limited amount of information after it has been removed from perception. It is a key cognitive ability, thought to play a role in other cognitive functions, including perception, attention and action. Given its importance, its accurate and efficient measurement is a major goal in working memory research....

Perceiving faces as attractive or not guides decisions to approach or date a person and can sway opinions in recruiting and legal proceedings. However, the mechanisms underlying facial attractiveness are not fully understood. While popular models of face recognition emphasize holistic processing, individuals often attempt to enhance their own attra...

Orientation perception is one of the most fundamental aspects of somatosensory perception, similar to its visual counterpart. In the current study, we examined several features of tactile orientation perception and their interactions, aiming to better understand the underlying mechanisms. We found that active exploration exhibits better orientation...

Food is fundamental to survival, and our brains are highly attuned to rapidly process food stimuli. Neural signals show that foods can be discriminated as edible or inedible as early as 85 ms after stimulus onset,¹ distinguished as processed or unprocessed beginning at 130 ms,² and as high or low density from 165 ms.³ Recent evidence revealed speci...

Every day we make thousands of saccades and take thousands of steps as we explore our environment. Despite their common co-occurrence in a typical active state, we know little about the coordination between eye movements, walking behaviour and related changes in cortical activity. Technical limitations have been a major impediment, which we overcom...

Investigating sensory processes in active human observers is critical for a holistic understanding of perception. Recent research has demonstrated that locomotion can alter visual detection performance in a rhythmic manner, illustrating how a very frequent and natural behaviour can influence sensory performance. Here we extend this line of work to...

It is important to investigate perception in the context of natural behaviour in order to reach a holistic account of how sensory processes are coordinated with actions. In particular, the effect of walking upon perceptual and cognitive functions has recently been investigated in the context of how common voluntary actions may dynamically impact up...

Attributing a visual motion signal to its correct source—be that external object motion, self-motion, or some combination of both—seems effortless, and yet often involves disentangling a complex web of motion signals. Existing literature focuses on either translational motion (heading) or eye movements, leaving much to be learnt about the influence...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) – when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) - when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

Locomotion has been shown to impact aspects of visual processing in both humans and animal models. In the current study, we assess the impact of locomotion on the dynamics of binocular rivalry. We presented orthogonal gratings, one contrast-modulating at 0.8 Hz (matching average step frequency) and the other at 3.2 Hz, to participants using a virtu...

Walking is among our most frequent and natural of voluntary behaviours, yet the consequences of locomotion upon perceptual and cognitive function remain largely unknown. Recent work has highlighted that although walking feels smooth and continuous, critical phases exist within each step for the successful coordination of perceptual and motor functi...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) - when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

Food is fundamental to survival and our brains are highly attuned to rapidly process food stimuli. Neural signals show foods can be discriminated as edible or inedible as early as 85 ms after stimulus onset ¹ , distinguished as processed or unprocessed beginning at 130 ms ² and as high or low density from 165 ms ³ . Recent evidence revealed special...

In order to effectively navigate the world around us, we must be able to correctly attribute motion signals to a wide variety of sources, including ourselves. Previous research has examined how we accurately split visual motion signals into those caused by self-motion or object motion, however this misses the key fact that we are active observers i...

Orientation processing is one of the most fundamental functions in both visual and somatosensory perception. Converging findings suggest that orientation processing in both modalities is closely linked: somatosensory neurons share a similar orientation organisation as visual neurons, and the visual cortex has been found to be heavily involved in ta...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) - when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) – when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

We report behavioural findings implying common motion processing for auditory and visual motion. We presented brief translational motion stimuli drifting leftwards or rightwards in the visual or auditory modality at various speeds. Observers made a speed discrimination on each trial, comparing current speed against mean speed (i.e., method of singl...

Recent evidence suggests that perceptual and cognitive functions are codetermined by rhythmic bodily states. Prior investigations have focused on the cardiac and respiratory rhythms, both of which are also known to synchronise with locomotion—arguably our most common and natural of voluntary behaviours. Compared to the cardiorespiratory rhythms, wa...

Enjoying a music concert is a multisensory experience, which mostly involves auditory and visual perception. However, the quality of acoustics and view may vary greatly within an auditorium. This study investigates preference at various seats within two size variations of an auditorium, through a virtual-reality subjective experiment with realistic...

Recent evidence suggests that perceptual and cognitive functions are codetermined by rhythmic bodily states. Prior investigations have focused on the cardiac and respiratory rhythms, both of which are also known to synchronise with locomotion - arguably our most common and natural of voluntary behaviours. Unlike the cardiorespiratory rhythms, walki...

When the eyes view separate and incompatible images, the brain suppresses one image and promotes the other into visual awareness. Periods of interocular suppression can be prolonged during continuous flash suppression (CFS) - when one eye views a static ‘target’ while the other views a complex dynamic stimulus. Measuring the time needed for a suppr...

Through development, multisensory systems reach a balance between stability and flexibility: the systems integrate optimally cross-modal signals from the same events, while remaining adaptive to environmental changes. Is continuous intersensory recalibration required to shape optimal integration mechanisms, or does multisensory integration develop...

Audiovisual integrations and interactions happen everywhere, including in music concerts, where combined visual and auditory perception contributes to overall enjoyment. Thirty-three participants evaluated their overall subjective preference at various seats in four virtual auditoria, which comprised congruent and incongruent auditory and visual re...

Continuous flash suppression (CFS) is a popular masking technique used to manipulate visual awareness. By presenting a rapidly changing stimulus to one eye (the ‘mask’), a static image viewed by the other (the ‘target’) may remain invisible for many seconds. This effectiveness affords a means to assess unconscious visual processing, leading to the...

Early models of multisensory integration posited that cross-modal signals only converged in higher-order association cortices and that vision automatically dominates. However, recent studies have challenged this view. In this study, the significance of the alignment of motion axes and spatial alignment across visual and tactile stimuli, as well as...

%%%%% full article access: https://authors.elsevier.com/a/1dhOs9jMU1CDM %%%%% Perceptual experience in the recent past has been shown to alter subsequent perception. Recently, it has been suggested that this “serial dependence” effect is modulated by sensory uncertainty. In the current study, by overlaying three different levels of visual noise (i...

Multisensory integration helps the brain build reliable models of the world and resolve ambiguities. Visual interactions with sound and touch are well established but vestibular influences on vision are less well studied. Here, we test the vestibular influence on vision using horizontally opposed motions presented one to each eye so that visual per...

Facial expressions are vital for social communication, yet the underlying mechanisms are still being discovered. Illusory faces perceived in objects (face pareidolia) are errors of face detection that share some neural mechanisms with human face processing. However, it is unknown whether expression in illusory faces engages the same mechanisms as h...

To maintain a continuous and coherent percept over time, the brain makes use of past sensory information to anticipate forthcoming stimuli. We recently showed that auditory experience of the immediate past is propagated through ear‐specific reverberations, manifested as rhythmic fluctuations of decision bias at alpha frequencies. Here, we apply the...

Short-term deprivation (2.5 h) of an eye has been shown to boost its relative ocular dominance in young adults. Here, we show that a much shorter deprivation period (3–6 min) produces a similar paradoxical boost that is retinotopic and reduces spatial inhibition on neighbouring, non-deprived areas. Partial deprivation was conducted in the left hemi...

In continuous flash suppression (CFS), an image presented to one eye is suppressed from awareness by a dynamic image masker presented to the other eye. Previous studies report that face stimuli break out of CFS more readily when they are oriented upright and contain ecologically relevant information such as facial expressions or direct eye gaze, po...

Previous work shows that observers can use information from optic flow to perceive the direction of self-motion (i.e. heading) and that perceived heading exhibits a bias towards the center of the display (center bias). More recent work shows that the brain is sensitive to serial correlations and the perception of current stimuli can be affected by...

To maintain a continuous and coherent percept over time, the brain makes use of past sensory information to anticipate forthcoming stimuli. We recently showed that auditory experience in the immediate past is propagated through ear-specific reverberations, manifested as rhythmic fluctuations of decision bias at alpha frequency. Here, we apply the s...

Natural image statistics exhibit temporal regularities of slow changes and short-term correlations and visual perception, too, is biased toward recently seen stimuli, i.e., a positive serial dependence. Some studies report strong individual differences in serial dependence in perceptual decision-making: some observers show positive serial effects,...

This study examines dual-task performance in the tactile modality and tests whether dual-task cost depends on task type. Experiment 1 involved competing tasks of the same type, using a primary localisation task on the left hand and a secondary localisation task on the right hand. In Experiment 2, the primary task on the left hand remained the same,...

Using a binocular rivalry paradigm combined with an orientation report task, Kim et al. find that the previous orientation biases the following perception only when it was consciously perceived. This shows that the priors for serial dependence are constructed at a later perceptual stage.

Perception is a proactive, "predictive" process, in which the brain relies, at least in part, on accumulated experience to make best guesses about the world to test against sensory data, updating the guesses as new experience is acquired. Using novel behavioral methods, the present study demonstrates the role of alpha rhythms in communicating past...

Visual perception can be systematically biased towards the recent past. Many stimulus attributes-including orientation, numerosity, facial expression and attractiveness, and perceived slimness-are systematically biased towards recent past experience. This phenomenon has been termed serial dependence. In the current study, we tested whether serial d...

Recent findings from several groups have demonstrated that visual perception at a given moment can be biased toward what was recently seen. This is true both for basic visual attributes and for more complex representations, such as face identity, gender, or expression. This assimilation to the recent past is a positive serial dependency, similar to...

Neural evidence suggests that mechanisms associated with conscious access (i.e., the ability to report on a conscious state) are "all-or-none". Upon crossing some threshold, neural signals are globally broadcast throughout the brain and allow conscious reports. However, whether subjective experience (phenomenal consciousness) is categorical (i.e.,...

Natural image statistics exhibit temporal regularities of slow changes and short-term correlations and visual perception, too, is biased towards recently seen stimuli, i.e., a positive serial dependence. Some studies report strong individual differences in serial dependence in perceptual decision making: some observers show positive serial effects,...

Recent exposure to asynchronous multisensory signals has been shown to shift perceived timing between the sensory modalities, a phenomenon known as 'temporal recalibration'. Recently, Van der Burg et al. (2013, J Neurosci, 33, pp. 14633-14637) reported results showing that recalibration to asynchronous audiovisual events can happen extremely rapidl...

Perception is sometimes bistable, switching between two possible interpretations. Levelt developed several propositions to explain bistable perception in binocular rivalry, based on a model of competing neural populations connected through reciprocal inhibition. Here we test Levelt's laws with bistable plaid motion. Plaids are typically tristable,...

It is known that moving visual stimuli are perceived to last longer than stationary stimuli with the same physical duration (Kanai, Paffen, Hogendoorn, & Verstraten, 2006), and that motor actions (Tomassini & Morrone, 2016) and eye movements (Morrone, Ross, & Burr, 2005) can alter perceived duration. In the present work, we investigated the contrib...

Sensory expectations from the accumulation of information over time exert strong predictive biases on forthcoming perceptual decisions. These anticipatory mechanisms help to maintain a coherent percept in a noisy environment. Here we present novel behavioural evidence that past sensory experience biases perceptual decisions rhythmically through alp...

Perception is modulated by ongoing brain oscillations. Psychophysical studies show a voluntary action can synchronize oscillations, producing rhythmical fluctuations of visual contrast sensitivity. We used signal detection to examine whether voluntary action could also synchronize oscillations in decision criterion, and whether that was due to the...

Continuous flash suppression (CFS) is a technique in which presenting one eye with a dynamic Mondrian sequence prevents a low-contrast target in the other eye from being perceived for many seconds. Frequently used to study unconscious visual processing, CFS bears many similarities with binocular rivalry (BR), another popular dichoptic stimulation t...

To interact effectively with the world, the brain must optimize its perception of the objects and events in the environment, many of which are signaled by more than one sense. Optimal perception requires the brain to integrate redundant cues from the different senses as efficiently as possible. One effective model of cue combination is maximum like...

The attentional sampling hypothesis suggests that attention rhythmically enhances sensory processing when attending to a single (~8 Hz), or multiple (~4 Hz) objects. Here we investigated whether attention samples sensory representations that are not part of the conscious percept during binocular rivalry. When crossmodally cued toward a conscious im...

Many studies have shown that recent history biases present perception, known as serial dependence, although it remains unclear whether it is driven by changes in perception or decision-making. Here we examined serial dependence for discriminating visual grating orientation (+45° or -45°) at threshold contrast. The grating was embedded in noise and...

sj-vid-2-ipe-10.1177 2041669518792930 - Supplemental material for Battle of the Mondrians: Investigating the Role of Unpredictability in Continuous Flash Suppression

sj-vid-3-ipe-10.1177 2041669518792930 - Supplemental material for Battle of the Mondrians: Investigating the Role of Unpredictability in Continuous Flash Suppression

sj-vid-1-ipe-10.1177 2041669518792930 - Supplemental material for Battle of the Mondrians: Investigating the Role of Unpredictability in Continuous Flash Suppression

The attentional sampling hypothesis suggests that attention rhythmically enhances sensory processing when attending to a single (~8 Hz), or multiple (~4 Hz) objects. Here we investigated using binocular rivalry whether attention samples sensory representations that are not part of the conscious percept, during competition for perceptual dominance....

In natural scenes, audiovisual events deriving from the same source are synchronized at their origin. However, from the perspective of the observer, there are likely to be significant multisensory delays due to physical and neural latencies. Fortunately, our brain appears to compensate for the resulting latency differences by rapidly adapting to as...

In continuous flash suppression (CFS), a dynamic sequence of Mondrian patterns presented to one eye suppresses a static target in the other eye for several seconds at a time. Its effectiveness has been linked to low-level properties such as spatial frequency and orientation, but the role of higher order influences remains unstudied. Here, using a t...

Continuous flash suppression (CFS) is a technique in which presenting one eyewith a dynamic Mondrian sequence prevents a low-contrast target in the other eye frombeing perceived for many seconds. Frequently used to study unconscious visualprocessing, CFS bears many similarities with binocular rivalry (BR), another populardichoptic stimulation techn...

Recent work from several groups has shown that perception of various visual attributes in human observers at a given moment is biased towards what was recently seen. This positive serial dependency is a kind of temporal averaging which exploits short-term correlations in visual scenes to reduce noise and stabilize perception. Here we test for seria...

Continuous flash suppression (CFS) is a popular technique whereby a dynamic sequence of Mondrian patterns is presented to one eye in order to suppress a static target presented to the other eye. Although the effectiveness of CFS is generally assumed to increase with the flicker rate of the Mondrian masker, a recent study has shown that suppression...

Continuous flash suppression (CFS) involves the presentation of a rapidly changing Mondrian sequence to one eye and a static target in the other eye. Targets presented in this manner remain suppressed for several seconds at a time, and this has seen the prevalent use of CFS in studies of unconscious visual processes. However, the mechanisms behind...

Many behavioral measures of visual perception fluctuate continually in a rhythmic manner, reflecting the influence of endogenous brain oscillations, particularly theta (∼4-7 Hz) and alpha (∼8-12 Hz) rhythms [1-3]. However, it is unclear whether these oscillations are unique to vision or whether auditory performance also oscillates [4, 5]. Several s...

Sustained exposure to an asynchronous multisensory signal causes perceived simultaneity to shift in the direction of the leading component of the adapting stimulus. This is known as temporal recalibration, and recent evidence suggests that it can occur very rapidly, even after a single asynchronous audiovisual (AV) stimulus. However, this form of r...

We investigated orientation categories in the guidance of attention in visual search. In the first two experiments, participants had a limited amount of time to find a target line among distractors lines. We systematically varied the orientation of the target and the angular difference between the target and distractors. We find vertical, horizonta...

Previous research has shown that when a moving stimulus is presented to a moving observer, the perceived speed of the stimulus is affected by vestibular self-motion signals (Hogendoorn, Verstraten, MacDougall, & Alais, 2017. Vision Research 130, 22-30.). This interaction was interpreted as a weighted sum of visual and vestibular motion signals. Thi...

Recent work from several groups has shown that perception of various visual attributes in human observers at a given moment is biased toward what was recently seen. This positive serial dependency is a kind of temporal averaging that exploits short-term correlations in visual scenes to reduce noise and stabilize perception. To date, this stabilizin...

We examined the recently discovered phenomenon of Adaptation-Induced Blindness (AIB), in which highly visible gratings with gradual onset profiles become invisible after exposure to a rapidly flickering grating, even at very high contrasts. Using very similar stimuli to those in the original AIB experiment, we replicated the original effect across...

Studies suggest that familiar faces are processed in a manner distinct from unfamiliar faces and that familiarity with a face confers an advantage in identity recognition. Our visual system seems to capitalize on experience to build stable face representations that are impervious to variation in retinal input that may occur due to changes in lighti...

[This corrects the article DOI: 10.1371/journal.pone.0160914.].