Perception最新文献

In order to achieve color constancy, the visual system needs to estimate the illuminant by referring to the chromatic distribution information in scenes where direct cues to the illuminant were absent. In this study, color constancy was investigated by an achromatic setting with short illuminant durations in five kinds of scenes with different numbers of colors and colored patches. Three of these scenes contained 8, 24, and 96 patches with different colors, and two other scenes contained 96 patches with 8 and 24 colors, respectively. All five scenes had identical space-averaged means, but different variances. The results showed that the color constancy index decreased as the variance of scene colors increased. This indicates that the effect of the number of colors and patches on color constancy was dependent on the scene variance they produced: a greater number of colors and patches tended to generate higher variance, which in turn led to lower color constancy indices. The results suggest that color constancy under brief exposure to multicolor scenes cannot be fully explained by models based on adaptation to the illuminant or mean chromaticity of the scene. Instead, the distribution of colors around the mean also plays an essential role.

Understanding everyday events is essential for navigating and facilitating successful social interactions. Face recognition is thought to play a critical role in how we associate and interpret events in the real world. In this study, we explored this issue using a natural viewing paradigm in which participants watched a movie containing a rich and detailed narrative. To determine the importance of face recognition in event comprehension, we compared age-matched, neurotypical control participants and individuals with developmental prosopagnosia (DP) - a lifelong deficit in the ability to recognize faces. After watching the movie, participants were assessed on their comprehension of the events from the movie. We found that DPs showed a significant reduction in their understanding of the events from the movie compared to neurotypical controls. We also found that individual differences in face recognition predicted event comprehension. Together, these results demonstrate the importance of face recognition for understanding naturally unfolding events in everyday life.

The Ebbinghaus illusion is a size illusion, in which a central circle appears larger or smaller depending on the size of surrounding circles. This illusion is widely used to study group-level differences in attentional processing, with the proposal that a local-processing bias reduces susceptibility to the Ebbinghaus illusion. One hundred and forty-five participants (87 young; 58 older) were included in the analyses. Participants completed the Navon hierarchical-figures task, to measure the global-local processing bias, and the Ebbinghaus illusion task, to measure susceptibility to the illusion. First, we investigated whether a strong local-processing bias reduced susceptibility to the Ebbinghaus illusion. Our findings did not support this proposal. At the group level, older participants demonstrated worse performance for global processing compared to young participants, but there were no age-group differences in susceptibility to the illusion. At the individual level, the young and older participants with the stronger local-processing bias were the participants with greater susceptibility to the illusion. Second, we investigated whether longer inspection times during the Ebbinghaus illusion task reduced susceptibility to the illusion. Our findings did support this proposal. At the group level, there were no age-group differences in either inspection time or susceptibility to the Ebbinghaus illusion. At the individual level, we replicated previous findings-the participants with the longer inspection times were the participants with the least susceptibility to the illusion. We discuss alternative cognitive mechanisms that may account for the Ebbinghaus illusion and their relevance to age-related changes and individual differences in visual attention.

The Two-Visual-Streams Hypothesis (TVSH) of vision proposes a functional separation between the perception of a visual stimulus and the control of visually guided action toward that stimulus. This study tested whether the separation of perception and action proposed by the TVSH is also demonstrated when executing visually guided cursor movements toward onscreen targets. Participants used a trackpad to click onscreen circular targets embedded within the Ebbinghaus ("Titchener Circles") illusion and were thus perceived as either larger or smaller than their true size. Participants were more accurate when clicking on the perceived larger target compared to the perceived smaller target, indicating their performance was influenced by their perception of target size (Experiment 1). There was no effect of the illusion when visual feedback of the target was removed at the beginning of the trial (Experiment 2) or removed following a 2-second target-viewing period (Experiment 3). Conclusion: The perceptual features of an onscreen stimulus mediate the guidance of cursor movements toward visible targets. Illusion-based perceptions of target size do not affect actions toward disappeared targets, however. These results contribute to the theoretical principles of the TVSH by testing its predictions in a novel onscreen environment.

Perceptual load theory states that there are limited processing resources, but that these must always be fully employed. It has been used to predict and explain the commonly reported finding that irrelevant distractors influence behaviour when the task has low load (such as processing just one target element) but not when the task has high load (processing many target elements). We attempted to replicate this effect over a series of six experiments that manipulated the location of the distractor, the duration of the display, and different levels of load. We examined both the distracting effects caused by a "neutral" distractor, and response-biases (congruence effects) that occur when the distractor is either congruent or incongruent with the target. Strong distraction and congruence effects were found with central distractors and weaker effects were found with peripheral distractors. These effects appeared to be independent of the level of perceptual load in all conditions. Our findings thus do not support the tenants of perceptual load theory and fail to replicate the many findings that do support this theory.

Stepping over obstacles requires adjusting the foot trajectory to avoid contact with surfaces that may be hazardous or unpleasant to step on. While it is well established that obstacle height and stability influence stepping behaviour, little is known about how perceptual affective evaluations, such as dangerousness, unpleasantness, and painfulness, modulate avoidance strategies. In Experiment 1 (N = 20), participants stepped over obstacles covered with stones varying in size and density while rating their perceived unpleasantness. Visual uncertainty was manipulated by comparing monocular and binocular viewing. Lead minimum foot clearance (MFC) was initially higher under monocular vision but decreased to binocular levels over trials. While obstacle unpleasantness did not systematically affect MFC or crossing step length, perceived unpleasantness ratings correlated weakly with crossing step length. However, because dangerousness and painfulness ratings were not collected, it remained unclear whether unpleasantness directly influenced avoidance behaviour or served as a proxy for perceived risk. To address this, Experiment 2 (N = 22) introduced obstacles covered with metal stud spikes or smooth surfaces, with additional ratings of dangerousness and painfulness. Results showed that MFC was higher for spiky than smooth obstacles. Crucially, in this experiment, ratings of perceived dangerousness, not unpleasantness, correlated positively with crossing step length, after controlling for other perceptual ratings. These findings suggest that perceptual affective properties modulate avoidance parameters. However, the nature of those modulations is stimulus specific and highly depends on task demands.

The fovea, with its high concentration of cone photoreceptors, results in increased sensitivity and visual acuity, while the periphery, with its lower contrast sensitivity and resolution, provides better spatial summation. Despite these differences, our experience of the visual field remains detailed and uniform, supported by the influence of central vision on peripheral vision. There is evidence that recognition of simple shapes in the periphery is enhanced by the presence of a similar shape in central vision. However, it is unclear whether such mechanisms generalise to more complex stimuli, such as faces. In a face matching task, we found that having a similar face in central vision improved face matching performance in the periphery. This suggests that general mechanisms govern the interaction between central and peripheral vision in recognising faces.

The composite effect, originally demonstrated for faces, has recently been shown to suggest holistic processing of words. The effect is associated with reading fluency in Latin script, but not in nonalphabetic Chinese script, suggesting that script properties influence its relationship with reading expertise. We measured the composite effect for Arabic, a visually complex alphabetic script that offers a useful contrast against Latin and Chinese. Arabic-English bilinguals ($N=$ 24), and English-only readers ($N=$ 22) completed a composite effect task, in which they judged whether the left or right halves of word pairs were the same or different. The unattended half was either congruent or incongruent with the judgement, and the halves were presented in aligned or misaligned blocks. The composite effect, a reduction in the effect of congruency when the halves are misaligned, typically is interpreted as evidence for holistic processing. Arabic-English readers showed the composite effect for Arabic words, whereas English-only readers did not. Both groups showed the effect for English words. The effect size for the two scripts was equivalent in Arabic-English readers. These findings suggest that the composite effect for Arabic words, like that of Latin script words, requires the ability to read the script. Graphemic complexity or the cursive property of the script appears not to play a role in the composite effect in skilled readers.

Cognitive associations between stimulus intensity and spatial response codes are thought to influence perceptual discrimination. We examined lateral response-set effects on auditory and visual intensity discrimination in a preregistered study with a large sample (N = 98). Participants responded to loud and bright stimuli using a button located to the left or right of the button used for soft and dim stimuli. In the auditory task, stimulus-response (SR)-mapping affected task-averaged error rates (ERs) but not task-averaged response times (RTs). However, loudness predicted response-side differences in both latency (${\text{RT}}_{\text{Left}}-{\text{RT}}_{\text{Right}}$) and accuracy (${\text{ER}}_{\text{Left}}-{\text{ER}}_{\text{Right}}$). By comparison, all tests of brightness discrimination supported the null or were inconclusive. Assessments of cross-modality correlations in SR-mapping effects were also inconclusive. These results replicate prior findings of lateral SR-mapping effects in auditory intensity discrimination and clarify inconsistencies in the visual domain. The lack of SR-mapping effects in brightness discrimination, along with inconclusive cross-modal correlations, challenges the notion of a common spatial processing mechanism for auditory and visual intensity comparison. If such a mechanism exists, its effects on visual judgments appear too subtle to be detected even in a large sample.