An implicit representation of stimulus ambiguity in pupil size.

To guide behavior, perceptual systems must operate on intrinsically ambiguous sensory input. Observers are usually able to acknowledge the uncertainty of their perception, but in some cases, they critically fail to do so. Here, we show that a physiological correlate of ambiguity can be found in pupil dilation even when the observer is not aware of such ambiguity. We used a well-known auditory ambiguous stimulus, known as the tritone paradox, which can induce the perception of an upward or downward pitch shift within the same individual. In two experiments, behavioral responses showed that listeners could not explicitly access the ambiguity in this stimulus, even though their responses varied from trial to trial. However, pupil dilation was larger for the more ambiguous cases. The ambiguity of the stimulus for each listener was indexed by the entropy of behavioral responses, and this entropy was also a significant predictor of pupil size. In particular, entropy explained additional variation in pupil size independent of the explicit judgment of confidence in the specific situation that we investigated, in which the two measures were decoupled. Our data thus suggest that stimulus ambiguity is implicitly represented in the brain even without explicit awareness of this ambiguity.

Confidence in visual motion discrimination is preserved in individuals with schizophrenia.

BACKGROUND: Metacognition is the set of reflexive processes that allows humans to evaluate the accuracy of their mental operations. Metacognitive deficits have been described in people with schizophrenia using mostly narrative assessment, and they have been linked to several key symptoms. METHODS: We assessed metacognitive performance objectively by asking people with schizophrenia or schizoaffective disorder (n = 20) and matched healthy participants (n = 21) to perform a visual discrimination task and report their confidence in their performance. Metacognitive performance was defined as the adequacy between visual discrimination performance and confidence. RESULTS: Bayesian analyses revealed equivalent metacognitive performance in the 2 groups, despite a weaker association between confidence and trajectory tracking during task execution among people with schizophrenia. We reproduced these results using an evidence accumulation model, which showed similar decisional processes in the 2 groups. LIMITATIONS: These results from a relatively small study sample cannot be generalized to other perceptual and nonperceptual tasks. To meet this purpose, ecological tasks are needed. As well, the role of antipsychotic medication and design deserves greater attention in the future. CONCLUSION: We found similar decisional and metacognitive capabilities between people with schizophrenia and healthy controls in a visual discrimination task.

Confidence as a Priority Signal.

When dealing with multiple tasks, we must establish the order in which to tackle them. In multiple experiments, including a preregistered replication (Ns = 16-105), we found that confidence, or the subjective accuracy of decisions, acts as a priority signal, both when ordering responses about tasks already completed or ordering tasks yet to be completed. Specifically, when participants categorized perceptual stimuli along two dimensions, they tended to first give the decision associated with higher confidence. When participants selected which of two tasks they wanted to perform first, they were slightly biased toward the task associated with higher confidence. This finding extends to nonperceptual decisions (mental calculation) and cannot be reduced to effects of task difficulty, response accuracy, response availability, or implicit demands. Our results thus support the role of confidence as a priority signal, thereby suggesting a new way in which it may regulate human behavior.

Priming by the variability of visual information.

According to recent theories, perception relies on summary representations that encode statistical information about the sensory environment. Here, we used perceptual priming to characterize the representations that mediate categorization of a complex visual array. Observers judged the average shape or color of a target visual array that was preceded by an irrelevant prime array. Manipulating the variability of task-relevant and task-irrelevant feature information in the prime and target orthogonally, we found that observers were faster to respond when the variability of feature information in the prime and target arrays matched. Critically, this effect occurred irrespective of whether the element-by-element features in the prime and target array overlapped or not, and was even present when prime and target features were drawn from opposing categories. This "priming by variance" phenomenon occurred with prime-target intervals as short as 100 ms. Further experiments showed that this effect did not depend on resource allocation, and occurred even when prime and target did not share the same spatial location. These results suggest that human observers adapt to the variability of visual information, and provide evidence for the existence of a low-level mechanism by which the range or dispersion of visual information is rapidly extracted. This information may in turn help to set the gain of neuronal processing during perceptual choice.

Unreliable evidence: 2 sources of uncertainty during perceptual choice.

Perceptual decisions often involve integrating evidence from multiple concurrently available sources. Uncertainty arises when the integrated (mean) evidence fails to support one alternative over another. However, evidence heterogeneity (variability) also provokes uncertainty. Here, we asked whether these 2 sources of uncertainty have independent behavioral and neural effects during choice. Human observers undergoing functional neuroimaging judged the average color or shape of a multielement array. The mean and variance of the feature values exerted independent influences on behavior and brain activity. Surprisingly, BOLD signals in the dorsomedial prefrontal cortex (dmPFC) showed polar opposite responses to the 2 sources of uncertainty, with the strongest response to ambiguous tallies of evidence (high mean uncertainty) and to homogenous arrays (low variance uncertainty). These findings present a challenge for models that emphasize the role of the dmPFC in detecting conflict, errors, or surprise. We suggest an alternative explanation, whereby evidence is processed with increased gain near the category boundary.

Concurrent repetition enhancement and suppression responses in extrastriate visual cortex.

Visual cortical responses are usually attenuated by repetition, a phenomenon known as repetition suppression (RS). Here, we use multivoxel pattern analyses of functional magnetic resonance imaging (fMRI) data to show that RS co-occurs with the converse phenomenon (repetition enhancement, RE) in a single cortical region. We presented human volunteers with short sequences of repeated faces and measured brain activity using fMRI. In an independently defined face-responsive extrastriate region, the response of each voxel to repetition (RS vs. RE) was consistent across scanner runs, and multivoxel patterns for both RS and RE voxels were stable. Moreover, RS and RE voxels responded to repetition with dissociable latencies and exhibited different patterns of connectivity with lower and higher visual regions. Computational simulations demonstrated that these effects must be due to differences in repetition sensitivity, and not feature selectivity. These findings establish that 2 classes of repetition responses coexist within 1 visual region and support models acknowledging this distinction, such as predictive coding models where perception requires the computation of both predictions (which are enhanced by repetition) and prediction errors (which are suppressed by repetition).

Robust averaging during perceptual judgment.

An optimal agent will base judgments on the strength and reliability of decision-relevant evidence. However, previous investigations of the computational mechanisms of perceptual judgments have focused on integration of the evidence mean (i.e., strength), and overlooked the contribution of evidence variance (i.e., reliability). Here, using a multielement averaging task, we show that human observers process heterogeneous decision-relevant evidence more slowly and less accurately, even when signal strength, signal-to-noise ratio, category uncertainty, and low-level perceptual variability are controlled for. Moreover, observers tend to exclude or downweight extreme samples of perceptual evidence, as a statistician might exclude an outlying data point. These phenomena are captured by a probabilistic optimal model in which observers integrate the log odds of each choice option. Robust averaging may have evolved to mitigate the influence of untrustworthy evidence in perceptual judgments.

The heuristics-and-biases inventory: An open-source tool to explore individual differences in rationality.

Over the last two decades, there has been a growing interest in the study of individual differences in how people's judgments and decisions deviate from normative standards. We conducted a systematic review of heuristics-and-biases tasks for which individual differences and their reliability were measured, which resulted in 41 biases measured over 108 studies, and suggested that reliable measures are still needed for some biases described in the literature. To encourage and facilitate future studies on heuristics and biases, we centralized the task materials in an online resource: The Heuristics-and-Biases Inventory (HBI; https://sites.google.com/view/hbiproject). We discuss how this inventory might help research progress on major issues such as the structure of rationality (single vs. multiple factors) and how biases relate to cognitive ability, personality, and real-world outcomes. We also consider how future research should improve and expand the HBI.

Metacognition tracks sensitivity following involuntary shifts of visual attention.

Salient, exogenous cues have been shown to induce a temporary boost of perceptual sensitivity in their immediate vicinity. In two experiments involving uninformative exogenous cues presented at various times before a target stimulus, we investigated whether human observers (N = 100) were able to monitor the involuntary increase in performance induced by such transients. We found that an increase of perceptual sensitivity (in a choice task) and encoding precision (in a free-estimation task) occurred approximately 100 ms after cue onset, and was accompanied by an increase in confidence about the perceptual response. These simultaneous changes in sensitivity and confidence resulted in stable metacognition across conditions. These results suggest that metacognition efficiently tracks the effects of a reflexive attentional mechanism known to evade voluntary control, and illustrate a striking ability of high-level cognition to capture fleeting, low-level sensory modulations.

From local to global estimations of confidence in perceptual decisions.

Perceptual confidence has been an important topic recently. However, one key limitation in current approaches is that most studies have focused on confidence judgments made for single decisions. In three experiments, we investigate how these local confidence judgments relate and contribute to global confidence judgments, by which observers summarize their performance over a series of perceptual decisions. We report two main results. First, we find that participants exhibit more overconfidence in their local than in their global judgments of performance, an observation mirroring the aggregation effect in knowledge-based decisions. We further show that this effect is specific to confidence judgments and does not reflect a calculation bias. Second, we document a novel effect by which participants' global confidence is larger for sets which are more heterogeneous in terms of difficulty, even when actual performance is controlled for. Surprisingly, we find that this effect of variability also occurs at the level of local confidence judgments, in a manner that fully explains the effect at the global level. Overall, our results indicate that global confidence is based on local confidence, although these two processes can be partially dissociated. We discuss possible theoretical accounts to relate and empirical investigations of how observers develop and use a global sense of perceptual confidence. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

How overconfidence bias influences suboptimality in perceptual decision making.

In perceptual decision making, it is often found that human observers combine sensory information and prior knowledge suboptimally. Typically, in detection tasks, when an alternative is a priori more likely to occur, observers choose it more frequently to account for the unequal base rate but not to the extent they should, a phenomenon referred to as "conservative decision bias" (i.e., observers do not shift their decision criterion enough). One theoretical explanation of this phenomenon is that observers are overconfident in their ability to interpret sensory information, resulting in overweighting the sensory information relative to prior knowledge. Here, we derived formally this candidate model, and we tested it in a visual discrimination task in which we manipulated the prior probabilities of occurrence of the stimuli. We measured confidence in decisions and decision criterion placement in two separate experimental sessions for the same participants (N = 69). Both overconfidence bias and conservative decision bias were found in our data, but critically the link that was predicted between these two quantities was absent. Our data suggested instead that when informed about the a priori probability, overconfident participants put less effort into processing sensory information. These findings offer new perspectives on the role of overconfidence bias to explain suboptimal decisions. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The striatum in time production: The model of Huntington's disease in longitudinal study.

The unified model of time processing suggests that the striatum is a central structure involved in all tasks that require the processing of temporal durations. Patients with Huntington's disease exhibit striatal degeneration and a deficit in time perception in interval timing tasks (i.e. for duration ranging from hundreds of milliseconds to minutes), but whether this deficit extends to time production remains unclear. In this study, we investigated whether symptomatic patients (HD, N = 101) or presymptomatic gene carriers (Pre-HD, N = 31) of Huntington's disease had a deficit in time production for durations between 4 and 10 s compared to healthy controls and whether this deficit developed over a year for patients. We found a clear deficit in temporal production for HD patients, whereas Pre-HD performed similarly to Controls. For HD patients and Pre-HD participants, task performance was correlated with grey matter volume in the amygdala and caudate, bilaterally. These results confirm that the striatum is involved in interval timing not only in perception but also in production, in accordance with the unified model of time processing. Furthermore, exploratory factor analyses on our data indicated that temporal production was associated with clinical assessments of psychomotor and executive functions. Finally, when retested twelve months later, the deficit of HD patients remained stable, although striatal degeneration was more pronounced. Thus, the simple, short and language-independent temporal production task may be a useful clinical tool to detect striatal degeneration in patients in early stages of Huntington's disease. However, its usefulness to detect presymptomatic stages or for monitoring the evolution of HD over a year seems limited.

Confidence in visual detection, familiarity and recollection judgments is preserved in schizophrenia spectrum disorder.

An effective way to quantify metacognitive performance is to ask participants to estimate their confidence in the accuracy of their response during a cognitive task. A recent meta-analysis1 raised the issue that most assessments of metacognitive performance in schizophrenia spectrum disorders may be confounded with cognitive deficits, which are known to be present in this population. Therefore, it remains unclear whether the reported metacognitive deficits are metacognitive in nature or rather inherited from cognitive deficits. Arbitrating between these two possibilities requires equating task performance between experimental groups. Here, we aimed to characterize metacognitive performance among individuals with schizophrenia across three tasks (visual detection, familiarity, recollection) using a within-subject design while controlling experimentally for intra-individual task performance and statistically for between-subject task performance. In line with our hypotheses, we found no metacognitive deficit for visual detection and familiarity judgments. While we expected metacognition for recollection to be specifically impaired among individuals with schizophrenia, we found evidence in favor of an absence of a deficit in that domain also. We found no specific metacognitive deficit in schizophrenia spectrum disorder in the visual or memory domain. The clinical relevance of our findings is discussed in light of a hierarchical framework of metacognition.

Modeling perceptual confidence and the confidence forced-choice paradigm.

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 sensitivity to the confidence evidence, and confidence boost accounts for information used for confidence judgment which was not used for the perceptual decision. The opposite effect of these two parameters creates a problem of confidence parameters indeterminacy, where the confidence in a perceptual decision is the same in spite of differences in confidence noise and confidence boost. When confidence is estimated for multiple stimulus strengths, both of these parameters can be recovered, thus allowing us to estimate whether confidence is generated using the same primary information that was used for the perceptual decision or some secondary information. We also describe a novel measure of confidence efficiency relative to the ideal confidence observer, as well as the estimate of one type of confidence bias. Finally, we apply the model to the confidence forced-choice paradigm, a paradigm that provides objective estimates of confidence, and we discuss how each parameter of the model can be recovered using this paradigm. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effects of false statements on visual perception hinge on social suggestibility.

Verbal hints can bias perceptual decision-making, even when the information they provide is false. What makes individuals more or less susceptible to such influences, however, remains unclear. Here, we inquire whether suggestibility to social influence, a high-level trait measured by a standard suggestibility scale, could predict changes in perceptual judgments. We asked naive participants to indicate the dominant color in a series of stimuli after giving them a short, false verbal statement about which color would likely dominate. We found that this statement biased participants' perceptual judgments of the dominant color, as shown by a correlated shift of their discrimination performance, confidence judgments, and response times. Crucially, this effect was more pronounced in participants with higher levels of susceptibility to social influence. Together, these results indicate that social suggestibility can determine how much simple (albeit false) verbal hints influence perceptual judgments. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Metacognitive improvement: Disentangling adaptive training from experimental confounds.

Metacognition is defined as the capacity to monitor and control one's own cognitive processes. Recently, Carpenter and colleagues (2019) reported that metacognitive performance can be improved through adaptive training: healthy participants performed a perceptual discrimination task, and subsequently indicated confidence in their response. Metacognitive performance, defined as how much information these confidence judgments contain about the accuracy of perceptual decisions, was found to increase in a group of participants receiving monetary reward based on their confidence judgments over hundreds of trials and multiple sessions. By contrast, in a control group where only perceptual performance was incentivized, metacognitive performance remained constant across experimental sessions. We identified two possible confounds that may have led to an artificial increase in metacognitive performance, namely the absence of reward in the initial session and an inconsistency between the reward scheme and the instructions about the confidence scale. We thus conducted a preregistered conceptual replication where all sessions were rewarded and where instructions were consistent with the reward scheme. Critically, once these two confounds were corrected we found moderate evidence for an absence of metacognitive training. Our data thus suggest that previous claims about metacognitive training are premature, and calls for more research on how to train individuals to monitor their own performance. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Consensus Goals in the Field of Visual Metacognition.

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 solving important problems rather than pursuing isolated, niche efforts. Here, 26 researchers from the field of visual metacognition reached consensus on four long-term and two medium-term common goals. We describe the process that we followed, the goals themselves, and our plans for accomplishing these goals. If this effort proves successful within the next few years, such consensus building around common goals could be adopted more widely in psychological science.

Perceptual awareness and categorical representation of faces: evidence from masked priming.

How internal categories influence how we perceive the world is a fundamental question in cognitive sciences. Yet, the relation between perceptual awareness and perceptual categorization has remained largely uncovered so far. Here, we addressed this question by focusing on face perception during subliminal and conscious perception. We used morphed continua between two face identities and we assessed, through a masked priming paradigm, the perceptual processing of these morphed faces under subliminal and supraliminal conditions. We found that priming from subliminal faces followed linearly the information present in the primes, while priming from visible faces revealed a non-linear profile, indicating a categorical processing of face identities. Our results thus point to a special relation between perceptual awareness and categorical processing of faces, and support the dissociation between two modes of information processing: a subliminal mode involving analog treatment of stimuli information, and a supraliminal mode relying on discrete representation.

Ensemble perception: Extracting the average of perceptual versus numerical stimuli.

Recent research has established that humans can extract the average perceptual feature over briefly presented arrays of visual elements or the average of a rapid temporal sequence of numbers. Here we compared the extraction of the average over briefly presented arrays, for a perceptual feature (orientations) and for numerical values (1-9 digits), using an identical experimental design for the two tasks. We hypothesized that the averaging of numbers, more than of orientations, would be constrained by capacity limitations. Arrays of Gabor elements or digits were simultaneously presented for 300 ms and observers were required to estimate the average on a continuous response scale. In each trial the elements were sampled from normal distributions (of various means) and we varied the set size (4-12). We found that while for orientation the averaging precision remained constant with set size, for numbers it decreased with set size. Using computational modeling we also extracted capacity parameters (the number of elements that are pooled in the average extraction). Despite marked heterogeneity between observers, the capacity for orientations (around eight items) was much larger than for numbers (around four items). The orientation task also had a larger fraction of participants relying on distributed attention to all elements. Our study thus supports the idea that numbers more than perceptual features are subject to capacity or attentional limitations when observers need to evaluate the average over an ensemble of stimuli.

Metacognitive blindness in temporal selection during the deployment of spatial attention.

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 this question, we adapted a "Wundt clocks" paradigm, asking observers (N=140) to reproduce the phase of a rotating clock at the time of an attentional cue, and to evaluate their confidence in their responses. Attention affected the latency between objective and perceived events: the average reported phase was delayed in accordance with the known latencies of voluntary and involuntary attention. Yet, we found that confidence remains oblivious to these attention-induced perceptual delays, like a 'metacognitive blind spot'. In addition, we observed weaker metacognition specifically during the deployment of voluntary attention, suggesting a tight relationship between the attentional and metacognitive systems. While previous work has considered how visual confidence adjusts to fully attended versus unattended locations, our study demonstrates that the very process of orienting attention in space can alter metacognition.