Pascal Mamassian

Ecole Normale Supérieure de Paris | ENS · Département d'Etudes Cognitives

Perceptual confidence is an important internal signal about the certainty of our decisions and there is a substantial debate on how it is computed. We highlight three confidence metric types from the literature: observers either use 1) the full probability distribution to compute probability correct (Probability metrics), 2) point estimates from th...

Despite the tangible progress in psychological and cognitive sciences over the last several years, these disciplines still trail other more mature sciences in identifying the most important questions that need to be solved. Reaching such consensus could lead to greater synergy across different laboratories, faster progress, and increased focus on s...

Multiple studies have shown that certain visual stimuli are perceived in accordance with strong biases that are both robust within individuals and highly variable from one individual to the next. These biases undergo small changes over time that demonstrate that they constitute latent states of the visual system. The literature to date indicates th...

Sensing the movement of fast objects within our visual environments is essential for controlling actions. It requires online estimation of motion direction and speed. We probed human speed representation using ocular tracking of stimuli of different statistics. First, we compared ocular responses to single drifting gratings (DGs) with a given set o...

Visual perception is not only shaped by sensitivity but also by confidence, i.e., the ability to estimate the accuracy of a visual decision. Younger observers have been reported to have access to a reliable measure of their own uncertainty when making visual decisions. This metacognitive ability might be challenged during ageing due to increasing s...

To interact safely with our environment, we must be able to judge our confidence in what we perceive. But what cues do we use to compute perceptual confidence? Geurts et al.1 decode brain activity and show that perceptual confidence is based on the distribution of sensory uncertainty, combining uncertainty driven by the input and the visual system.

Perceptual confidence is an important internal signal about the certainty of our decisions and there is a substantial debate on how it is computed. We highlight three confidence metric types from the literature: observers either use 1) the full probability distribution to compute probability correct (Probability metrics), 2) point estimates from th...

How does orienting attention in space affect the quality of our confidence judgments? Orienting attention to a particular location is known to boost visual performance, but the deployment of attention is far from being instantaneous. Whether observers are able to monitor the time needed for attention to deploy remains largely unknown. To address th...

Perceptual confidence is an evaluation of the validity of perceptual decisions. While there is behavioural evidence that confidence evaluation differs from perceptual decision-making, disentangling these two processes remains a challenge at the neural level. Here, we examined the electrical brain activity of human participants in a protracted perce...

Perceptual confidence is an evaluation of the validity of our perceptual decisions. We present here a complete generative model that describes how confidence judgments result from some confidence evidence. The model that generates confidence evidence has two main parameters, confidence noise and confidence boost. Confidence noise reduces the sensit...

Visual perception is not only shaped by sensitivity, but also by confidence, i.e. the ability to estimate the accuracy of a visual decision. There is robust evidence that younger observers have access to a reliable measure of their own uncertainty when making visual decisions. This metacognitive ability might be challenged during aging due to incre...

Perceptual decisions are typically accompanied by a subjective sense of (un)certainty. There is robust evidence that observers have access to a reliable estimate of their own uncertainty and can judge the validity of their perceptual decisions. However, there is still a debate to what extent these meta-perceptual judgements underly a common mechani...

Movement execution is not always optimal. Understanding how humans evaluate their own motor decisions can give us insights into their suboptimality. Here we investigated how humans time the action of synchronizing an arm movement with a predictable visual event, and how well they can evaluate the outcome of this action. On each trial, participants...

Sensory adaptation is a useful tool to identify the links between perceptual effects and neural mechanisms. Even though motion adaptation is one of the earliest and most documented aftereffects, few studies have investigated the perception of direction and speed of the aftereffect at the same time, that is the perceived velocity. Using a novel expe...

Despite the tangible progress in psychological and cognitive sciences over the last several years, the discipline still trails other more mature sciences in identifying the most important questions that need to be solved. Reaching such consensus could lead to greater synergy across disciplines, faster progress, and increased focus on solving import...

Visual confidence is the observers’ estimate of their precision in one single perceptual decision. Ultimately, however, observers often need to judge their confidence over a task in general rather than merely on one single decision. Here, we measured the global confidence acquired across multiple perceptual decisions. Participants performed a dual...

Visual perception is not instantaneous. It takes a few milliseconds for light to be transduced in photoreceptors and tens of milliseconds more for neuronal spikes to occur at successive levels of the visual hierarchy. Moreover, the latency of responses varies across the visual field and the cortical hierarchy. In peripheral compared to central visi...

The precision to locate individual features in depth can often be improved by integrating information over space. However, this integration can sometimes be extremely detrimental, as for example in the case of the Westheimer-McKee phenomenon where features are grouped to form an object. We replicate here the known loss of precision in this phenomen...

To best interact with the external world, humans are often required to consider the quality of their actions. Sometimes the environment furnishes rewards or punishments to signal action efficacy. However, when such feedback is absent or only partial, we must rely on internally generated signals to evaluate our performance (i.e., metacognition). Yet...

Visual confidence is the observers’ estimate of their precision in one single perceptual decision. Ultimately, however, observers often need to judge their confidence over a task in general rather than merely on one single decision. Here, we measured the global confidence acquired across multiple perceptual decisions. Participants performed a dual...

Priors and payoffs are known to affect perceptual decision-making, but little is understood about how they influence confidence judgments. For optimal perceptual decision-making, both priors and payoffs should be considered when selecting a response. However, for confidence to reflect the probability of being correct in a perceptual decision, prior...

[ The paper has now been published in Cognition: Recht, S., de Gardelle, V., and Mamassian, P. (2021). "Metacognitive blindness in temporal selection during the deployment of spatial attention." Cognition 216:104864, DOI: 10.1016/j.cognition.2021.104864. ] How does orienting attention in space affect the quality of our confidence judgments? Orien...

We investigated whether the moment at which an event is perceived depends on its temporal context. Participants learned a mapping between time and space by watching the hand of a clock rotating a full revolution in a fixed duration. Then the hand was removed, and a target disc was flashed within a fixed-interval duration. Participants were to indic...

To best interact with the external world, humans are often required to consider the quality of their actions. Sometimes the environment furnishes rewards or punishments to signal action efficacy. However, when such feedback is absent or only partial, we must rely on internally generated signals to evaluate our performance (i.e., metacognition). Yet...

Temporal attention enhances the perceptual representation of a stimulus at a particular point in time. The number of possible attentional episodes in a given period is limited, but whether observers’ confidence reflects such limitations is still unclear. To investigate this issue, we adapted an “Attentional Blink” paradigm, presenting observers wit...

Priors and payoffs are known to change perceptual decision-making, but little is understood about how they influence confidence judgments. Human observers performed an orientation-discrimination task with varied priors and payoffs. We investigated the subsequent placement of discrimination and confidence criteria by comparing behavior to several pl...

What has been previously experienced can systematically affect human perception in the present. We designed a novel psychophysical experiment to measure the perceptual effects of adapting to dynamically changing stimulus statistics. Observers are presented with a series of oriented Gabor patches and are asked occasionally to judge the orientation o...

Does the moment when an event is perceived depends on where it is presented? To measure when participants perceived events, they were first familiarized with trial duration, by watching the hand of a clock rotating. Then, the hand was removed, and stimuli were presented at a random time from the trial onset. Participants indicated the location wher...

[This work has now been published in Scientific Reports: "Temporal attention causes systematic biases in visual confidence", doi: https://doi.org/10.1038/s41598-019-48063-x ] Accurate decision-making requires estimating the uncertainty of perceptual events. Temporal attention is known to enhance the selection of a stimulus at a relevant time, but...

Prominent models of time perception assume a reset of the timing mechanism with an explicit onset of the interval to be timed. Here we investigated the accuracy and precision of temporal estimations when the duration does not have such an explicit onset. Participants were tracking a disc moving on a circular path with varying speeds, and estimated...

Interacting with the natural environment leads to complex stimulations of our senses. Here we focus on the estimation of visual speed, a critical source of information for the survival of many animal species as they monitor moving prey or approaching dangers. In mammals, and in particular in primates, speed information is conceived to be represente...

The material property of glossiness, which is attributed to many objects in our daily life, is physically independent of the objects' color. However, perceived glossiness can change with the contrast between the highlight and the area around the specular highlight. Hitherto, experiments mainly investigated gloss on unicolored surfaces. It is well k...

Interactions between the albedo and the gloss on a surface are commonplace. Darker surfaces are perceived glossier (contrast gloss) than lighter surfaces and darker backgrounds can enhance perceived lightness of surfaces. We used maximum likelihood conjoint measurements to simultaneously quantify the strength of those effects. We quantified the ext...

Visual confidence refers to an observer’s ability to judge the accuracy of her perceptual decisions. Even though confidence judgments have been recorded since the early days of psychophysics, only recently have they been recognized as essential for a deeper understanding of visual perception. The reluctance to study visual confidence may have come...

The use of separate multisensory signals is often beneficial. A prominent example is the speed-up of responses to two redundant signals relative to the components, which is known as the redundant signals effect (RSE). A convenient explanation for the effect is statistical facilitation, which is inherent in the basic architecture of race models (Raa...

Visual confidence refers to the ability to predict one's own performance. Thus for confidence to be useful, it must be well calibrated with performance. How then does confidence change when percepts are modified due to adaptation (aftereffects). Observers were instructed to estimate their confidence across 2 different perceptual tasks. In an orient...

Superposition of two dot clouds moving in different directions results in the perception of two transparent layers. Despite the ambiguous depth order of the layers, there are consistent preferences to perceive the layer, which is moving either rightward or downward in front of the other layer. Here we investigated the origin of these depth order bi...

The idea of a common currency underlying our choice behaviour has played an important role in sciences of behaviour, from neurobiology to psychology and economics. However, while it has been mainly investigated in terms of values, with a common scale on which goods would be evaluated and compared, the question of a common scale for subjective proba...

When we look straight at an object, it appears the same as when it is seen from the corner of our eye; however, this stability of visual appearance can collapse if inconspicuous object changes are introduced during eye movements.

Studies of perception usually emphasize processes that are largely universal across observers and-except for short-term fluctuations-stationary over time. Here we test the universality and stationarity assumptions with two families of ambiguous visual stimuli. Each stimulus can be perceived in two different ways, parameterized by two opposite direc...

Young children use multiple cues to appreciate the three-dimensional structure of the world. A new study reveals that these cues are properly integrated only years later, thus showing that sensory development is protracted well into teenage years.

Superposition of two dot clouds moving in different directions results in the perception of two transparent layers with ambiguous depth order. Intriguingly, the layer moving downwards or rightwards is preferentially seen in front (Mamassian & Wallace, 2010). Here we investigated which motion properties are causing these directional biases. In four...

We have previously (Wexler & Mamassian, VSS 2014) reported that there exist two independent biases related to the perception of 3D shape and motion from optic flow. These biases are both robust within observers, and highly variable across observers. Here we present a quantitative analysis of time series of these two variables, sampled once a day ov...

Perceptual judgments are often associated with a feeling of confidence, which is typically measured by collecting a confidence judgment after each perceptual decision. However, this single decision confidence is potentially quite different from the more general feeling of confidence that one has when facing a task. To address this issue, we designe...

Whether a surface is glossy or matte is physically independent of whether it is light or dark. Perceptually however, the albedo of specularly or diffusely reflecting surfaces can strongly influence perceived gloss (Pellacini et al., 2000, Proceedings of SIGGRAPH). Here we ask whether glossiness judgments are more constrained if there are variations...

The perception of stimuli depends, in part, on the properties of stimuli seen in the past. We examined the characteristics of observers' responses based on the stimuli they were shown and the responses they gave going back several minutes, Critically, we manipulated the statistics of the stimuli to be in a position to model the dynamics of these hi...

Stereoscopic systems present binocular images on planar surface at a fixed distance. They induce cues to flatness, indicating that images are presented on a unique surface and specifying the relative depth of that surface. The center of interest of this study is on a second problem, arising when a 3D object distance differs from the display distanc...

Humans can not only perform some visual tasks with great precision, they can also judge how good they are in these tasks. However, it remains unclear how observers produce such metacognitive evaluations, and how these evaluations might be dissociated from the performance in the visual task. Here, we hypothesized that some stimulus variables could a...

We often encounter pairs of variables in the world whose mutual relationship can be described by a function. After training, human responses closely correspond to these functional relationships. Here we study how humans predict unobserved segments of a function that they have been trained on and we compare how human predictions differ to those made...

When observers are asked to match the depth of an object according to its height, they often report systematic errors depending on viewing distance. Systematic biases can also arise while vergence distances are induced by binocular disparities. Observers of stereoscopic images tend to overestimate the depth of objects displayed in front of the scre...

This study investigates the audio-visual spatial congruence in distance dimension in the case of virtual environments. A perceptual study is conducted in which visual targets are presented using a passive 3D projector, and accompanying virtual sounds are simulated by Wave Field Synthesis. Audio-visual stimuli are spatially congruent in azimuth and...

"Confidence" commonly refers to the judgment of one's performance in general knowledge (memory), motor performance (action), or sensory faculty (perception). However, in most laboratory studies of perceptual confidence, observers make confidence judgments on individual trials or responses, which does not involve the judgment of overall task perform...

An event defined by two sensory modalities has better precision than either modality alone (Ernst & Banks, 2002, Nature; Alais & Burr, 2004, Curr Bio). Is the original precision of one modality still available once bimodal combination occurs? We used a perceptual confidence judgement to address this issue. Perceptual confidence (the subjective sens...

The presence of a bright, specular highlight is one of the most important factors in gloss perception. Previous work has shown that even when highlights cover only a small region on a surface, they lead to the impression that an object has a uniform surface material (Beck 1981, Percept. Psychophys.). In the present study we investigate whether perc...

Observers show idiosyncratic biases in the perception of multistable stimuli, such as in the perception of tilt from structure-from-motion stimuli and in the perception of depth order in motion transparency. By measuring biases across a sampling of all surface tilts and motion directions, we show the perception of these stimuli in a vast majority o...

Repeated stimulus presentations can lead to dramatic changes in the perception of subsequent stimuli. Two such phenomena are biased perception (after-effects) due to adaptation and increased sensitivity due to perceptual learning. Here we study the interaction of these two phenomena and present a model accounting for both. Observers were asked to i...

The brain combines information from different senses to improve performance on perceptual tasks. For instance, auditory processing is enhanced by the mere fact that a visual input is processed simultaneously. However, the sensory processing of one modality is itself subject to diverse influences. Namely, perceptual processing depends on the degree...

With the broader use of stereoscopic displays, a flurry of research activity about the accommodation-vergence conflict has emerged to highlight the implications for the human visual system. In stereoscopic displays, the introduction of binocular disparities requires the eyes to make vergence movements. In this study, we examined vergence dynamics w...