• Bai & Scholl
• Belledonne, Yildirim, & Scholl
• Erdogan, Bi, Yildirim, & Scholl
• Walter-Terrill, Ongchoco, & Scholl
• Wong, Shah, & Scholl

The perception of multiple shapes depends on how they are arranged: you might see distinct objects, or you might see a single *group*. What cues drive such grouping? Classic answers involve simple physical relationships such as proximity or common motion. Here, in contrast, we ask whether perceptual groups can also be formed by *social* cues -- as when the movement of simple shapes triggers an impression of goal-directed agency. To find out, we explored the flip-side of grouping: loss of individuality. Previous work has shown that when observers must quickly estimate the number of discs in a display, for example, estimates will be lower when pairs of discs are grouped by thin lines. Does social grouping due to shared goals lead to a similar loss of individuality? Observers viewed short (e.g. 1.5 s) animations of moving 'dart' shapes. Darts moved randomly, but rotated so as to continuously point at a common target (a moving disc). This display yields a vivid impression of collective goal-directed behavior (known as the Wolfpack effect): despite the random movement, the shapes appear to share the common goal of pursuing the target. In contrast, when darts are always oriented 90deg away from the target (thus equating rotary motion correlation), such impressions are destroyed. Observers viewed variable numbers of darts, and simply estimated how many were present on each trial. The results were striking: numerical estimates were reliably lower for Wolfpack displays compared to equated 90•-rotation displays -- and this was true for a range of different numerosities, and even for observers who reported not noticing the darts' related orientations. This suggests that shared goals can lead to perceptual grouping and a corresponding loss of individuality. In this way, social groups may be central not only to social cognition, but also to visual processing.

So much of perception is effortless, but a hallmark property of sustained visual attention is a vivid sense of effort. Nowhere is this more evident than during multiple object tracking (MOT), where keeping track of a group of moving targets amidst identical moving distractors involves a distinct sense of exertion. But where does this sense of effort come from? The answer is not immediately obvious, in part because of the dynamic nature of MOT: each MOT trial is almost an experiment unto itself, with a moment-by-moment ebb and flow of effort, as the proximities of targets and distractors constantly change. Accordingly, we asked a straightforward question (with a surprising answer): how does the feeling of retrospective effort (at the end of a trial) relate to the moment-by-moment experience of effort during a trial? To find out, we augmented MOT in two ways. First, during tracking, subjects reported their moment-by-moment sense of effort using a continuous dial (with the continuously varying pitch of a tone providing feedback that did not interfere with tracking). Second, immediately after each trial, subjects used a slider to report how effortful tracking was overall. Retrospective effort was not simply the average of moment-by-moment effort, but rather was best explained by certain brief moments -- especially the *peak* effort, and the effort near the *end* of each tracking interval. These moments provided maximal predictive power: adding the other moment-by-moment effort ratings did not improve prediction of retrospective effort, and this was not true for any other temporal windows. This peak/end pattern is characteristic of retrospective reports of many other properties at longer time-scales -- from the joy of a vacation, to the pain of a surgery. These results thus demonstrate a striking convergence between a hallmark effect of cognition and the moment-by-moment dynamics of visual phenomenology.

Visual processing seems specialized in several ways for the perception of other agents, and one of the best examples of this is biological motion -- as when displays of moving dots ('point-light walkers'; PLWs) give rise to rich percepts of locomoting agents. Despite thousands of experiments over decades of research, one of the most foundational questions about such phenomena remains unsettled: just how specific are they to *biological* motion? Addressing this question is challenging, largely because of the absence of non-biological comparison stimuli -- since the translation or rotation of rigid objects (as in familiar structure-from-motion displays) lacks the rich characteristic *relative* motion of the points from PLWs. Here, to fill this gap, we introduce a novel visual phenomenon: the perception of rich behavior from dynamic point-light *cloths* (PLCs) -- as when a sheet on a clothesline is waving in the wind. Across many experiments, we found broad similarities between the perception of PLWs and PLCs -- in terms of both experimental results and phenomenological demonstrations. In the first place, people readily perceive the dynamic shape and behavior of cloths from point-light displays, and (as with PLWs) this depends critically on the points' relative motions, since such rich percepts disappear both in static displays and in dynamic displays with spatially scrambled points. This applies not only to the perception of cloth structure itself, but also to more nuanced properties, such as a fabric's stiffness. Moreover, the perception of PLCs is also highly robust, persisting (as do PLWs) e.g. even in displays with limited-lifetime points, or when embedded in noise. These results collectively demonstrate how the perception of rich internal structure from dynamic point-light displays transcends biological motion, and also applies to the behavior of other sorts of non-rigid entities: even beyond biology, the visual system extracts rich structure from surprisingly limited input.

Visual perception is often effortless, but not always: reading, for example, is faster and easier with some fonts compared to others. Such differences in visual *fluency* (the ease, or lack thereof, of information processing) can have profound effects on higher-level cognition and decision-making. When a written passage is held constant, for example, its author may nevertheless be judged as less intelligent (or the message may be judged as less truthful) when the passage is written in a disfluent (but still legible) font. Such effects are often normatively inappropriate, insofar as the 'vehicle' of a message (e.g. its font) has no necessary bearing on its actual content (e.g. its truth). Are such effects specific to visual processing, per se, or do they reflect more general perceptual principles? To find out, we explored analogous perceptual (dis)fluency in the auditory domain. In the modern era, the sounds of voices are often determined not only by intrinsic qualities (such as vocal anatomy), but also by extrinsic properties (such as videoconferencing microphone quality). We show that such superficial auditory properties also have surprisingly deep consequences for higher-level social judgments. Listeners heard short narrated passages (e.g. from job application essays), and then made various judgments about the speakers. Critically, the recordings were modified to simulate different microphone qualities, while carefully equating listeners' comprehension of the words themselves. Common disfluent auditory signals (as in 'tinny' speech) led to lower judgments of intelligence, hireability, credibility, and romantic desirability. These effects were robust across speaker gender and accent, and occurred for both human and clearly artificial (computer-synthesized) speech. (And such effects may become more impactful as daily communication via videoconferencing becomes increasingly prevalent.) These results demonstrate that such fluency effects reflect a more abstract form of information processing that transcends visual perception.

A central goal of perception and cognition is to predict how events in our local environments are likely to unfold: what is about to happen? And of course some of the most reliable ways of answering this question involve considering the regularities of physics. Accordingly, a great deal of recent research throughout cognitive science has explored the nature of 'intuitive physics'. The vast majority of this work, however, has involved higher-level reasoning, rather than seeing itself -- as when people are asked to deliberate about how objects might move, in response to explicit questions ("Will it fall?"). Here, in contrast, we ask whether the apprehension of certain physical properties of scenes might also occur *unconsciously*, during simple passive viewing. Moreover, we ask whether certain physical regularities are not just processed, but also visually *prioritized* -- as when a tower is about to fall. Observers viewed block towers -- some stable, some unstable -- defined in terms of whether they would collapse as a result of external physical forces (such as gravity) alone. We used continuous flash suppression (CFS) to render the towers initially invisible: observers viewed them monocularly through a mirror haploscope, while a dynamic Mondrian mask was presented to their other eye. We then measured how long towers took to break through this interocular suppression, as observers indicated when they became visually aware of anything other than the mask. The results were clear and striking: unstable towers broke into visual awareness faster than stable towers. And this held even while controlling for other visual properties -- e.g. while contrasting pairs of stable vs. unstable towers sharing the same convex hull, and differing only in the horizontal placement of a single block. This work shows how physical instability is both detected and prioritized, not only during overt deliberation, but also in unconscious visual processing.