Perceptual (roots of) core knowledge.

Some core knowledge may be rooted in - or even identical to - well-characterized mechanisms of mid-level visual perception and attention. In the decades since it was first proposed, this possibility has inspired (and has been supported by) several discoveries in both infant cognition and adult perception, but it also faces several challenges. To what degree does What Babies Know reflect how babies see and attend?

Perceived gaze dynamics in social interactions can alter (and even reverse) the perceived temporal order of events.

Here's an all-too-familiar scenario: Person A is staring at person B, and then B turns toward A, and A immediately looks away (a phenomenon we call 'gaze deflection'). Beyond perceiving lower-level properties here - such as the timing of the eye/head turns - you can also readily perceive seemingly higher-level social dynamics: A got caught staring, and frantically looked away in embarrassment! It seems natural to assume that such social impressions are based on more fundamental representations of what happened when - but here we show that social gaze dynamics are unexpectedly powerful in that they can actually alter (and even reverse) the perceived temporal order of the underlying events. Across eight experiments, observers misperceived B as turning before A, when in fact they turned simultaneously - and even when B was turning after A. Additional controls confirmed that this illusion depends on visual processing (vs. being driven solely by higher-level interpretations), and that it is specific to the perception of social agents (vs. non-social objects). This demonstrates how social perception is tightly integrated into our perceptual experience of the world, and can have powerful consequences for one of the most basic properties that we can perceive: what happens when.

What's next?: Time is subjectively dilated not only for 'oddball' events, but also for events immediately after oddballs.

Our experience of time is strikingly plastic: Depending on contextual factors, the same objective duration can seem to fly by or drag on. Perhaps the most direct demonstration of such subjective time dilation is the oddball effect: when seeing identical objects appear one after another, followed by an "oddball" (e.g., a disc that suddenly grows in size, in a sequence of otherwise static discs), observers experience this oddball as having lasted longer than its nonoddball counterparts. Despite extensive work on this phenomenon, a surprisingly foundational question remains unasked: What actually gets dilated? Beyond the oddball, are the objects just before (or just after) the oddball also dilated? As in previous studies, observers viewed sequences of colored discs, one of which could be the oddball-and subsequently reproduced the oddball's duration. Unlike previous studies, however, there were also critical trials in which observers instead reproduced the duration of the disc immediately before or after the oddball. A clear pattern emerged: oddball-induced time dilation extended to the post-oddball disc, but not the pre-oddball disc. Whence this temporal asymmetry? We suggest that an oddball's sudden appearance may induce uncertainty about what will happen next, heightening attention until after the uncertainty is resolved.

Visual event boundaries restrict anchoring effects in decision-making.

Research on higher-level thought has revealed many principles of reasoning and decision-making but has rarely made contact with how we perceive the world in the first place. Here we show how a lower-level property of perception-the spontaneous and task-irrelevant segmentation of continuous visual stimulation into discrete events-can restrict one of the most notorious biases in decision-making: numerical anchoring. Subjects walked down a long room in an immersive three dimensional (3D) animation and then made a numerical judgment (e.g., of how much a suitcase is worth, or of how many hours of community service a minor crime deserved). Critically, some subjects passed through a doorway (a visual event boundary) during their virtual walk, while others did not-equating time, distance traveled, and visual complexity. The anchoring manipulation was especially innocuous, not appearing to be part of the experiment at all. Before the online trial began, subjects reported the two-digit numerical value from a visually distorted "CAPTCHA" ("to verify that you are human")-where this task-irrelevant anchor was either low (e.g., 29) or high (e.g., 92). With no doorway, we observed reliable anchoring effects: Higher CAPTCHA values produced higher estimates. With the doorway, however, such effects were attenuated or even eliminated. This generalized across tasks involving item valuations, factual questions, and legal judgments and in tests of both incidental and explicit anchoring. This demonstrates how spontaneous visual event segmentation can have profound consequences for higher-level thought.

Event segmentation structures temporal experience: Simultaneous dilation and contraction in rhythmic reproductions.

We experience the world in terms of both (continuous) time and (discrete) events, but time seems especially primitive-since we cannot perceive events without an underlying temporal medium. It is all the more intriguing, then, to discover that event segmentation can itself influence how we perceive the passage of time. We demonstrated this using a novel "rhythmic reproduction" task, in which people listened to irregular sequences of musical tones, and then immediately reproduced those rhythmic patterns from memory. Each sequence contained a single salient (and entirely task-irrelevant) perceptual event boundary, but the temporal placement of that boundary varied across multiple trials in which people reproduced the same underlying rhythmic pattern. Reproductions were systematically influenced by event boundaries in two complementary ways: tones immediately following event boundaries were delayed (being effectively played "too late" in the reproductions), while tones immediately preceding event boundaries were sped up (being effectively played "too early"). This demonstrates how event segmentation influences time perception in subtle and nonuniform ways that go beyond global temporal distortions-with dilation across events, but contraction within events. Events structure temporal experience, facilitating a give-and-take between the subjective expansion and contraction of time. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Here it comes: Active forgetting triggered even just by anticipation of an impending event boundary.

Visual input arrives in a continuous stream, but we often experience the world as a sequence of discrete events - and the boundaries between events have important consequences for our mental lives. Perhaps the best example of this is that memory not only declines as a function of elapsed time, but is also impaired when crossing an event boundary - as when walking through a doorway. (This impairment may be adaptive, as when one "flushes" a cache in a computer program when completing a function.) But when exactly does this impairment occur? Existing work has not asked this question: based on a reasonable assumption that forgetting occurs when we cross event boundaries, memory has only been tested after this point. Here we demonstrate that even visual cues to an impending event boundary (that one has not yet crossed) suffice to trigger forgetting. Subjects viewed an immersive animation that simulated walking through a room. Before their walk, they saw a list of pseudo-words, and immediately after their walk, their recognition memory was tested. During their walk, some subjects passed through a doorway, while others did not (equating time and distance traveled). Memory was impaired (relative to the "no doorway" condition) not only when they passed through the doorway, but also when they were tested just before they would have crossed the doorway. Additional controls confirmed that this was due to the anticipation of event boundaries (rather than differential surprise or visual complexity). Visual processing may proactively "flush" memory to some degree in preparation for future events.

Seeing Soft Materials Draped Over Objects: A Case Study of Intuitive Physics in Perception, Attention, and Memory.

We typically think of intuitive physics in terms of high-level cognition, but might aspects of physics also be extracted during lower-level visual processing? Might we not only think about physics, but also see it? We explored this using multiple tasks in online adult samples with objects covered by soft materials-as when you see a chair with a blanket draped over it-where you must account for the physical interactions between cloth, gravity, and object. In multiple change-detection experiments (n = 200), observers from an online testing marketplace were better at detecting image changes involving underlying object structure versus those involving only the superficial folds of cloths-even when the latter were more extreme along several dimensions. And in probe-comparison experiments (n = 100), performance was worse when both probes (vs. only one) appeared on image regions reflective of underlying object structure (equating visual properties). This work collectively shows how vision uses intuitive physics to recover the deeper underlying structure of scenes.

Flexible Goals Require that Inflexible Perceptual Systems Produce Veridical Representations: Implications for Realism as Revealed by Evolutionary Simulations.

How veridical is perception? Rather than representing objects as they actually exist in the world, might perception instead represent objects only in terms of the utility they offer to an observer? Previous work employed evolutionary modeling to show that under certain assumptions, natural selection favors such "strict-interface" perceptual systems. This view has fueled considerable debate, but we think that discussions so far have failed to consider the implications of two critical aspects of perception. First, while existing models have explored single utility functions, perception will often serve multiple largely independent goals. (Sometimes when looking at a stick you want to know how appropriate it would be as kindling for a campfire, and other times you want to know how appropriate it would be as a weapon for self-defense.) Second, perception often operates in an inflexible, automatic manner-proving "impenetrable" to shifting higher-level goals. (When your goal shifts from "burning" to "fighting," your visual experience does not dramatically transform.) These two points have important implications for the veridicality of perception. In particular, as the need for flexible goals increases, inflexible perceptual systems must become more veridical. We support this position by providing evidence from evolutionary simulations that as the number of independent utility functions increases, the distinction between "interface" and "veridical" perceptual systems dissolves. Although natural selection evaluates perceptual systems only on their fitness, the most fit perceptual systems may nevertheless represent the world as it is.

Hallucinating visual structure: Individual differences in 'scaffolded attention'.

Our percepts usually derive their structure from particular cues in the incoming sensory information, but this is not so in the phenomenon of scaffolded attention - where shifting patterns of attention give rise to 'everyday hallucinations' of visual structure even in the absence of sensory cues. When looking at a piece of graph paper, for example, the squares are all identical - yet many people see a shifting array of structured patterns such as lines, crosses, or even block-letters - something that doesn't occur when staring at a blank page. We have informally noted that scaffolded attention is a widely but not universally shared phenomenon - with some people spontaneously experiencing such percepts (even without instruction), others seeing such 'phantom' structures only when actively trying to so, and still others never having such experiences at all. Accordingly, the present study assessed the prevalence of scaffolded attention - both as an ability, and a spontaneous phenomenon. These results were then correlated with several measures of imagery and attention, in an attempt to explain the nature and origin of such individual differences. 40% of observers experienced scaffolded attention spontaneously, and 78% did so when trying - and these differences were uniquely modulated by certain measures of attention (such as attentional breadth, as measured by the 'functional field of view'), but not by measures of the vividness or spontaneity of mental imagery. These results inspire an explanation for scaffolded attention based on spontaneous perceptual grouping.

"Taste typicality" is a foundational and multi-modal dimension of ordinary aesthetic experience.

Aesthetic experience seems both regular and idiosyncratic. On one hand, there are powerful regularities in what we tend to find attractive versus unattractive (e.g., beaches versus mud puddles).1-4 On the other hand, our tastes also vary dramatically from person to person:5-8 what one of us finds beautiful, another might find distasteful. What is the nature of such differences? They may in part be arbitrary-e.g., reflecting specific past judgments (such as liking red towels over blue ones because they were once cheaper). However, they may also in part be systematic-reflecting deeper differences in perception and/or cognition. We assessed the systematicity of aesthetic taste by exploring its typicality for the first time across seeing and hearing. Observers rated the aesthetic appeal of ordinary scenes and objects (e.g., beaches, buildings, and books) and environmental sounds (e.g., doorbells, dripping, and dialtones). We then measured "taste typicality" (separately for each modality) in terms of the similarity between each individual's aesthetic preferences and the population's average. The data revealed two primary patterns. First, taste typicality was not arbitrary but rather was correlated to a moderate degree across seeing and hearing: people who have typical taste for images also tend to have typical taste for sounds. Second, taste typicality captured most of the explainable variance in people's impressions, showing that it is the primary dimension along which aesthetic tastes systematically vary.

Unconscious pupillometry: An effect of "attentional contagion" in the absence of visual awareness.

When looking at other people, we can readily tell how attentive (or distracted) they are. Some cues to this are fairly obvious (as when someone stares intensely at you), but others seem more subtle. For example, increased cognitive load or emotional arousal causes one's pupils to dilate. This phenomenon is frequently employed as a physiological measure of arousal, in studies of pupillometry. Here, in contrast, we employ it as a stimulus for social perception. Might the human visual system be naturally and automatically engaging in "unconscious pupillometry"? We demonstrate that faces rendered invisible (through continuous flash suppression) enter awareness faster when their pupils are dilated. This cannot be explained by appeal to differential contrast, differential attractiveness, or spatial attentional biases, and the effect vanishes when the identical stimuli are presented in socially meaningless ways (e.g., as shirt buttons or facial moles). These results demonstrate that pupil dilation is prioritized in visual processing even outside the focus of conscious awareness, in a form of unconscious "attentional contagion." (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Scaffolded attention in time: 'Everyday hallucinations' of rhythmic patterns from regular auditory beats.

A regular grid (e.g. on a piece of graph paper) is made up of squares which (by definition) have no structure. When people stare at such a grid, however, they may nevertheless see a shifting array of structured patterns such as lines, crosses, or even block-letters - something that doesn't occur when staring at a blank page. This is the phenomenon of scaffolded attention, and recent work has demonstrated that this involves the creation of bona fide object representations (e.g. that enjoy 'same-object advantages'). Is this an intrinsically visuospatial phenomenon, or might it rather reflect a much more general effect of perceiving structure from regular scaffolds, which could also occur in other dimensions or modalities? Here we show for the first time that there is also robust scaffolded attention in time: a regular series of tones (as might come from a metronome) has no structure beyond the 'beats' themselves, but people nevertheless hear a shifting array of structured rhythms - a phenomenon that doesn't occur when listening to silence. We demonstrate (in tests of temporal 'same-event advantages') that this (entirely internal) process gives rise to bona fide event representations. Thus the relationship between attention and events is bidirectional: event structure can guide attention, but attention can also create event structure in the first place. In this way we show how 'everyday hallucinations' of rhythmic patterns can arise in the absence of explicit sensory structure.

Hidden intentions: Visual awareness prioritizes perceived attention even without eyes or faces.

Eye contact is a powerful social signal, and it readily captures attention. Recent work has suggested that direct gaze is prioritized even unconsciously: faces rendered invisible via interocular suppression enter awareness faster when they look directly at (vs. away from) you. Such effects may be driven in a relatively low level way by the special visual properties of eyes, per se, but here we asked whether they might instead arise from the perception of a deeper property: being the focus of another agent's attention and/or intentions. We report five experiments which collectively explore whether visual awareness also prioritizes distinctly non-eye-like stimuli that nevertheless convey directedness. We first showed that directed (vs. averted) 'mouth' shapes also break through into awareness faster, after being rendered invisible by continuous flash suppression - a direct 'gaze' effect without any eyes. But such effects could still be specific to faces (if not eyes), so we next asked whether the prioritization of directed intentions would still occur even for stimuli that have no faces at all. In fact, even simple geometric shapes can be seen as intentional, as when numerous randomly scattered cones are all consistently pointing at you. And indeed, even such directed (vs. averted) cones entered awareness faster - a direct 'gaze' effect without any facial cues. Additional control experiments ruled out effects of both symmetry and response biases. We conclude that the perception of directed intentions is sufficient to boost objects into awareness, and that putative eye-contact effects might instead reflect more general phenomena of 'mind contact'.

The Efficiency of Demography in Face Perception.

When we look at a face, we cannot help but "read" it: Beyond simply processing its identity, we also form robust impressions of both transient psychological states (e.g., surprise) and stable character traits (e.g., trustworthiness). But perhaps the most fundamental traits we extract from faces are their social demographics, for example, race, age, and gender. How much exposure is required to extract such properties? Curiously, despite extensive work on the temporal efficiency of extracting both higher-level social properties (such as competence and dominance) and more basic characteristics (such as identity and familiarity), this question remains largely unexplored for demography. We correlated observers' percepts of the race/age/gender of unfamiliar faces viewed at several brief durations (and then masked) with their judgments after unlimited exposure. Performance reached asymptote by 100 ms, was above chance by only 33.33 ms, and had a similar temporal profile to detecting faces in the first place. This was true even when the property to be reported wasn't revealed until after the face had disappeared, and when the faces were matched for several lower-level visual properties. Collectively, these results demonstrate that the extraction of demographic features from faces is highly efficient, and can truly be done at a glance.

Visual memorability in the absence of semantic content.

What determines how well people remember images? Most past research has explored properties of the people doing the remembering - such as their age, emotional state, or individual capacity. However, recent work has also characterized memorability - the likelihood of an image being remembered across observers. But what makes some images more memorable than others? Part of the answer must surely involve the meanings of the images, but here we ask whether this is the entire story: is there also purely visual memorability, driven not by semantic content but by perceptual features per se? We isolated visual memorability in an especially direct manner - by eliminating semantic content while retaining many visual properties. We did so by transforming a set of natural scene images using phase scrambling, and then testing memorability for both intact and scrambled images in independent samples. Across several experiments, observers saw sequences of images and responded anytime they saw a repeated image. We found reliable purely visual memorability at the temporal scales of both short-term memory (2-15 s) and longer-term memory (several minutes), and this could not be explained by the extent to which people could generate semantic labels for some scrambled images. Collectively, these results suggest that the memorability of images is a function not only of what they mean, but also of how they look in the first place.

The center cannot hold: Variations of frame width help to explain the "inward bias" in aesthetic preferences.

Although most visual aesthetic preferences are likely driven by a mix of personal, historical, and cultural factors, there are exceptions: some may be driven by adaptive mechanisms of visual processing, and so may be relatively consistent across people, contexts, and time. An especially powerful example is the "inward bias": when a framed image contains a figure (e.g., a face in profile), people prefer arrangements in which the figure faces inward. Although the inward bias has been studied in many contexts, its underlying nature remains unclear. It may be a function of an image's center (as in the "affordance-space" account, in which people prefer to center the implied functional extensions of objects), or it may be a function of the frame's borders (as in the "looking-into-the-future" account, in which people dislike perspectives on scenes that won't allow them to witness predicted future actions). Here we directly contrast these possibilities using a simple novel manipulation. Observers placed a face (in profile) in a frame to maximize the image's aesthetic appeal, and across observers we varied the frame's aspect ratio. We observed a powerful inward bias, and across frame widths observers preferred an approximately constant positive ratio of space in front versus behind the face. This suggests that the inward bias is driven primarily not by the image's center, but by the frame's borders - and it is consistent with the possibility that certain regions of empty space are prioritized because they are where future actions are predicted to occur.

Gaze deflection reveals how gaze cueing is tuned to extract the mind behind the eyes.

Suppose you are surreptitiously looking at someone, and then when they catch you staring at them, you immediately turn away. This is a social phenomenon that almost everyone experiences occasionally. In such experiences-which we will call gaze deflection-the "deflected" gaze is not directed at anything in particular but simply away from the other person. As such, this is a rare instance where we may turn to look in a direction without intending to look there specifically. Here we show that gaze cues are markedly less effective at orienting an observer's attention when they are seen as deflected in this way-even controlling for low-level visual properties. We conclude that gaze cueing is a sophisticated mental phenomenon: It is not merely driven by perceived eye or head motions but is rather well tuned to extract the "mind" behind the eyes.

Retinotopic adaptation reveals distinct categories of causal perception.

We can perceive not only low-level features of events such as color and motion, but also seemingly higher-level properties such as causality. A prototypical example of causal perception is the 'launching effect': one object (A) moves toward a stationary second object (B) until they are adjacent, at which point A stops and B starts moving in the same direction. Beyond these motions themselves - and regardless of any higher-level beliefs - this display induces a vivid visual impression of causality, wherein A is seen to cause B's motion. Do such percepts reflect a unitary category of visual processing, or might there be multiple distinct forms of causal perception? While launching is often simply equated with causal perception, researchers have sometimes described other phenomena such as 'triggering' (in which B moves faster than A) and 'entraining' (in which A continues to move alongside B). We used psychophysical methods to determine whether these labels really carve visual processing at its joints, and how putatively different forms of causal perception relate to each other. Previous research demonstrated retinotopically specific adaptation to causality: exposure to causal launching makes subsequent ambiguous events in that same location more likely to be seen as non-causal 'passing'. Here, after replicating this effect, we show that exposure to triggering also yields retinotopically specific adaptation for subsequent ambiguous launching displays, but that exposure to entraining does not. Collectively, these results reveal that visual processing distinguishes some (but not all) types of causal interactions.

Gazing Without Eyes: A "Stare-in-the-Crowd" Effect Induced by Simple Geometric Shapes.

Of the many effects that eye contact has, perhaps the most powerful is the stare-in-the-crowd effect, wherein faces are detected more readily when they look directly toward you. This is commonly attributed to others' eyes being especially salient visual stimuli, but here we ask whether stares-in-the-crowd might arise instead from a deeper property that the eyes (but not only the eyes) signify: the direction of others' attention and intentions. In fact, even simple geometric shapes can be seen as intentional, as when numerous randomly scattered cones are all consistently pointing at you. Accordingly, we show here that cones directed at the observer are detected faster (in fields of averted cones) than are cones averted away from the observer (in fields of directed cones). These results suggest that perceived intentionality itself captures attention-and that even in the absence of eyes, others' directed attention stands out in a crowd.