When believing is seeing: The role of predictions in shaping visual perception

The study investigated the influence of predictions on perception—in particular, how strong but erroneous prediction coupled with poor sensory data can trigger misperceptions. Using signal detection, we tested whether predictions induced by a semantic cue change the recognition threshold (criterion) or the subjectively perceived differences between stimuli (sensitivity). In a series of 3 experiments, participants observed pictures of (a) real objects distorted to various extents (targets), (b) noise with elements corresponding to meaningful objects (foils), or (c) nonsense images (noise). Stimuli were preceded either by a semantic cue or by a blank screen with equal probability. Presence of the cue resulted in a more liberal criterion, but only for targets and foils. The cue decreased sensitivity between the distorted targets, but increased sensitivity between the targets and noise—that is, the cue increased between-class differences, but decreased within-class differences. When there was no correspondence between prediction and the sensory input, prediction actually increased the chances of correctly rejecting noise. The influence of the cue was strongest for the moderately distorted targets and foils—when uncertainty related to the bottom-up input was the highest.     

When seeing is not believing: A critique of priest's argument from perception

In this paper I critically examine an argument proposed by Graham Priest in support of the claim that the observable world is consistent. According to this argument we have good reason to think that the observable world is consistent, specifically we perceive it to be consistent. I critique this argument on two fronts. First, Priest appears to reason from the claim ‘we know what it is to have a contradictory perception’ to the claim ‘we know what it is to perceive a contradiction’. I argue that this inference fails to be valid. Secondly, I give reasons for thinking that if an observable state of affairs were to be contradictory, we would perceive it to be consistent. As such that the world we observe appears consistent does not constitute evidence that it is in fact consistent. That we see a consistent world is no reason to believe that the world is consistent. I conclude the paper with some reflections on the implications of this analysis for the plausibility of trivialism.     

When seeing is knowing: the role of visual cues in the dissociation between children's rule knowledge and rule use

The Dimensional Change Card Sort (DCCS) task requires children to switch from sorting cards based on shape or color to sorting based on the other dimension. Typically, 3-year-olds perseverate, whereas 4-year-olds flexibly sort by different dimensions. Zelazo and colleagues (1996, Cognitive Development, 11, 37-63) asked children questions about the postswitch rules and found an apparent dissociation between rule knowledge and rule use, namely that 3-year-olds demonstrate accurate knowledge of the postswitch rules despite sorting cards incorrectly. Here, we show that children's success with these questions is grounded in their use of available visual cues; children who fail sorting use the target cards to correctly answer questions, and when the cards are unavailable they guess. This suggests that there might not be a dissociation between children's rule knowledge and rule use in the DCCS.     

When distance pays off: The role of construal level in spending predictions

Self predictions are often optimistically biased, even for recurrent events. People could generate more realistic predictions by using information about past experiences, however they tend to disregard this cognitive approach. Drawing on Construal Level Theory, we propose that increases in construal level facilitate the use of information from past experience, and thereby increase prediction accuracy. This proposal was tested in two studies examining predictions of personal spending. Consistent with the hypotheses, individuals induced to construe the prediction target at a higher level of abstraction generated more accurate predictions (Study 1) and the effect of increased construal level on prediction was attributable to a greater reliance on past experience (Studies 1 and 2). The findings indicate that high-level construal can sometimes benefit prediction accuracy.     

Believing is seeing: the effects of racial labels and implicit beliefs on face perception

Two studies tested whether racial category labels and lay beliefs about human traits have a combined effect on people's perception of, and memory for, racially ambiguous faces. Participants saw a morphed target face accompanied by a racial label (Black or White). Later, they were asked to identify the face from a set of two new morphed faces, one more Black and the other more White than the target. As predicted, entity theorists, who believe traits are immutable, perceived and remembered the target face as consistent with the racial label, whereas incremental theorists, who believe traits are malleable, perceived and remembered the face as inconsistent with the racial label. In Study 2, participants also drew the target face more consistently (entity theorists) or less consistently (incremental theorists) with the racial label. Results of both studies confirm that social variables can affect how physical features are seen and remembered.     

Social perception from visual cues: role of the STS region

Social perception refers to initial stages in the processing of information that culminates in the accurate analysis of the dispositions and intentions of other individuals. Single-cell recordings in monkeys, and neurophysiological and neuroimaging studies in humans, reveal that cerebral cortex in and near the superior temporal sulcus (STS) region is an important component of this perceptual system. In monkeys and humans, the STS region is activated by movements of the eyes, mouth, hands and body, suggesting that it is involved in analysis of biological motion. However, it is also activated by static images of the face and body, suggesting that it is sensitive to implied motion and more generally to stimuli that signal the actions of another individual. Subsequent analysis of socially relevant stimuli is carried out in the amygdala and orbitofrontal cortex, which supports a three-structure model proposed by Brothers. The homology of human and monkey areas involved in social perception, and the functional interrelationships between the STS region and the ventral face area, are unresolved issues.     

When sound affects vision: effects of auditory grouping on visual motion perception

Two identical visual targets moving across each other can be perceived either to bounce off or to stream through each other. A brief sound at the moment the targets coincide biases perception toward bouncing. We found that this bounce-inducing effect was attenuated when other identical sounds (auditory flankers) were presented 300 ms before and after the simultaneous sound. The attenuation occurred only when the simultaneous sound and auditory flankers had similar acoustic characteristics and the simultaneous sound was not salient. These results suggest that there is an aspect of auditory-grouping (saliency-assigning) processes that is context-sensitive and can be utilized by the visual system for solving ambiguity. Furthermore, control experiments revealed that such auditory context did not affect the perceptual qualities of the simultaneous sound. Because the attenuation effect is not manifest in the perception of acoustic characteristics of individual sound elements, we conclude that it is a genuine cross-modal effect.     

When believing in the union is (not) enough: The role of threat and norms in intentions to act on union legitimacy and efficacy beliefs

Three field studies conducted with academics and students examined the dynamic role of threat and normative support for a union in qualifying the relationship between union‐related legitimacy and efficacy beliefs, and union intentions. There was evidence for interplay between threat and norms in facilitating people acting in accordance with their union beliefs, and in providing the conditions where those with weaker beliefs may be mobilised. In Study 1, students' perception of threat to group interests facilitated their preparedness to act on pro‐union legitimacy and efficacy beliefs. In Study 2, among academics who perceived low threat, acting on union legitimacy and efficacy beliefs was contingent on a pro‐union norm, while those who perceived high threat were prepared to act on their union legitimacy beliefs regardless of the normative environment. Finally, in Study 3, a pro‐union norm again facilitated acting on union beliefs in a low threat condition and overcame the importance of legitimacy and efficacy beliefs in a high threat condition. In sum, this research makes a case for the importance of union strategies attending to both the framing of intergroup threat and the communication of in‐group normative support for the union.     

The role of structure in infant visual pattern perception

The research of the authors and others on the role of structure in infant visual pattern perception is reviewed. Two new experiments are reported on preference for symmetry in infants. It is shown that infants reliably prefer patterns with multiple axes of bilateral symmetry relative to asymmetrical patterns. Also, the results demonstrate that vertically oriented single axis bilateral symmetry is more salient than horizontally oriented symmetry in infants as it is in adults. It is argued that sensitivity to various kinds of pattern structure reflects fundamental operations of the visual system.     

The role of structural redundancy in the perception of visual targets

Most visual images contain “gross shapes” which are highly correlated with less perceptable “details,” e.g., the gross outline of a head and details such as eyes, ears, etc. The role of such structural redundancy in perception is considered both from a “syntactical” and “spatial-frequency” view of structure. An experiment is reported and evaluated in terms of a simple mathematical model which allows one to isolate the influence of several factors in the perceptual process, particularly the observer’s actual sensitivity to specific details and the influence of the redundant (correlated) information in “higher order forms,” The basic idea is that one decides whether a particular (target) detail is present in a briefly presented image by integrating impressions from various parts of the image in a weighted manner, with the weights determined by redundant information in “higher order forms.” Furthermore, the results are generally consistent with the notion that an increase in the number of attended letters does not reduce the information extracted from each letter.     

The role of central processes in the perception of visual after-images

Three experiments are reported in which part of the stimulus to be after-imaged was presented to each eye, producing simultaneous, binocular, after-images. In each case the monocular stimuli were complementary to each other, so that the binocular combination constituted a meaningful whole. The subjects' reports on the appearances and fragmentations of their after-images suggest the existence of some central, integrative, mechanism.     

Seeing and believing: perception,belief formation and the divided mind

On many of the idealized models of human cognition and behavior in use by philosophers, agents are represented as having a single corpus of beliefs which (a) is consistent and deductively closed, and (b) guides all of their (rational, deliberate, intentional) actions all the time. In graded-belief frameworks, agents are represented as having a single, coherent distribution of credences, which guides all of their (rational, deliberate, intentional) actions all of the time. It’s clear that actual human beings don’t live up to this idealization. The systems of belief that we in fact have are fragmented. Rather than having a single system of beliefs that guides all of our behavior all of the time, we have a number of distinct, compartmentalized systems of belief, different ones of which drive different aspects of our behavior in different contexts. It’s tempting to think that, while of course people are fragmented, it would be better (from the perspective of rationality) if they weren’t, and the only reason why our fragmentation is excusable is that we have limited cognitive resources, which prevents us from holding too much information before our minds at a time. Give us enough additional processing capacity, and there’d be no justification for any continued fragmentation. I argue that this is not so. There are good reasons to be fragmented rather than unified, independent of the limitations on our available processing power. In particular, there are ways our belief-forming mechanisms—including our perceptual systems—could be constructed that would make it better to be fragmented than to be unified. And there are reasons to think that some of our belief-forming mechanisms really are constructed that way.

Seeing is believing: the reality of hypnotic hallucinations

Two experiments investigated the reality attributed to hypnotic suggestion through subtle projection of a visual image during simultaneous suggestion for a visual hallucination that resembled the projected image. In Experiment 1, high and low hypnotizable participants were administered either a hypnotic induction or wake instructions, given a suggestion to hallucinate a shape, and then the projected image was subsequently introduced. Although highs in both conditions rated the projected image more vividly than lows, highs in the hypnosis (but not wake) condition made comparable reality ratings when the projected image was absent and present. In Experiment 2, high hypnotizable participants were administered a suggestion to see a shape on a wall. For half the participants the suggested image was projected on the wall and then removed, and for half the projection was initially absent and then introduced. Participants who had the projection absent and then present reported comparable reality and vividness ratings when the projection was absent and present. These findings indicate that elevated hypnotizability and hypnosis are associated with attributions of external reality to suggested experiences.     

Sensing without seeing in comparative visual search

Rensink [Rensink, R. A. (2004). Visual sensing without seeing. Psychological Science, 15(1), 27-32] has presented evidence suggesting visual changes may be sensed without an accompanying visual experience. Here, we report two experiments in which we monitored observers' eye-movements whilst they searched for a difference between two simultaneously presented images and pressed separate response keys when a difference was seen or sensed. We first assessed whether sensing performance was random by collecting ratings of confidence in the validity of sensing and assessing gaze location during sensing. Sensing was not random: fixation position and confidence ratings were different when a difference was present compared to catch trials. Furthermore, the uniformity of objects in the images and the type of difference appear to affect seeing and sensing differently, suggesting that these processes are dissociated. The possibility is discussed of a sensing mechanism that increases vigilance toward unconsciously registered differences, particularly changes to scene layout.     

Field dependence and the role of visual frameworks in the perception of size

The extent to which apparent size is relationally determined has been studied by Rock and Ebenholtz and by Wenderoth, who came to widely differing conclusions as to the magnitude of this phenomenon. In both studies, a large range of individual differences was observed. In the present study, an attempt was made to account for variations in the influence of visual contexts on the perception of size by relating them to the cognitive style dimension of field dependence/independence. In two situations, relativelyfield-dependent observers made size judgments which were influenced by a frame surrounding the target figure, while relatively field-independent observers made size judgments which were influenced by a frame surrounding the target figure, while relatively field-independent observers tended to be less influenced by the frame, making their judgments approximate the retinal size of the target. The results suggest that assessment of the magnitude of the relational determination of apparent size must consider the cognitive style of the observers as well as situational variations.     

When power is undeserved: its effects on perception and social judgements

This paper explores the impact of the legitimacy of power position on powerholders' impressions, expectancies' confirmation processes, and decisions about subordinates in the context of a personnel selection process. Participants were assigned to a power position (they were told they will be representatives in a students conference and they will be able to select a mate to go also to the conference and to work under their supervision) on the basis of positive feedback regarding their supervisory skills (legitimate) or negative feedback regarding their supervisory skills (illegitimate). Two applicants were proposed as subordinates: one high in sociability and competence and the other low in both dimensions. Although participants in the two conditions noticed the superiority of one candidate over the other, illegitimate powerholders selected the least sociable and competent subordinate more often than legitimate powerholders. Illegitimate participants also request more information about the best than about the worse candidate. We interpret our findings in light of the larger literature suggesting an impact of illegitimacy on people's attempts to rationalize and justify their position as well as to perpetuate the existing social arrangement.     

When half a face is as good as a whole: Effects of simple substantial occlusion on visual and audiovisual speech perception

The visible movement of a talker's face is an influential component of speech perception. However, the ability of this influence to function when large areas of the face (~50%) are covered by simple substantial occlusions, and so are not visible to the observer, has yet to be fully determined. In Experiment 1, both visual speech identification and the influence of visual speech on identifying congruent and incongruent auditory speech were investigated using displays of a whole (unoccluded) talking face and of the same face occluded vertically so that the entire left or right hemiface was covered. Both the identification of visual speech and its influence on auditory speech perception were identical across all three face displays. Experiment 2 replicated and extended these results, showing that visual and audiovisual speech perception also functioned well with other simple substantial occlusions (horizontal and diagonal). Indeed, displays in which entire upper facial areas were occluded produced performance levels equal to those obtained with unoccluded displays. Occluding entire lower facial areas elicited some impairments in performance, but visual speech perception and visual speech influences on auditory speech perception were still apparent. Finally, implications of these findings for understanding the processes supporting visual and audiovisual speech perception are discussed.     

The role of phenomenal displacement on the perception of the visual upright

Tilt invariably involves the factor of displacement. A clockwise rotation of a rod, for example, results in the top being displaced to the right and the bottom to the left. The question was raised as to which is primary, displacement or tilt. Through a series of experiments, apparent tilt was found to be the perceptual outcome of phenomenal displacement. In addition, gravity seemed to play no significant role in determining the visual upright. Therefore, the conventionally accepted field theory of apparent verticality was rejected and the visual upright was interpreted according to principles which govern the perception of motion and radial direction.     

When a reappearance is old news: visual marking survives occlusion

Performance in a visual search task becomes more efficient if half of the distractors are presented before the rest of the stimuli. This "preview benefit" may partly be due to inhibition of the old (previewed) items. The preview effect is abolished, however, if the old items offset briefly before reappearing (D. G. Watson & G. W. Humphreys, 1997). The authors examined whether this offset effect still occurred if the old items undergo occlusion. Results show that a preview benefit was found when the old items were occluded but not otherwise, consistent with the idea of top-down attentional inhibition being applied to the old items. The preview benefit is attenuated, however, by movement of the irrelevant stimuli in the displays.