Attention shapes what we see and what we act upon by allocating limited resources to certain parts of visual display in a selective and adaptive manner. While most previous studies in visual attention mainly focused on the attentional distribution over space or features, recent studies have revealed that temporal dynamics also plays a crucial function in visual attention. This paper reviews the representation, function and neural mechanism of temporal dynamics in visual attention from the following four aspects: (1) Tracking dynamic structure of external stimulus by attention; (2) Intrinsic dynamic characteristics of attention; (3) Time-based multiple object representation; (4) Relationship between visual dynamics and classical attentional phenomena. We propose that the dynamic structure and temporal organization are fundamental to visual attention, and the research on it might provide new solutions to many unresolved issues in visual attention research.
Attention ; Humans ; Visual Perception

Recent sensory history plays a critical role in the perception of event duration. For example, repetitive exposure to a particular duration leads to the distortion of subsequent duration perception. This phenomenon, termed duration adaptation, induces a robust repulsive duration aftereffect. In particular, adaptation to relatively long sensory events shortens the perceived duration of a subsequent event, while adaptation to relatively short sensory events lengthens the perception of subsequent event durations. This phenomenon implies the plasticity of duration perception and offers important clues for revealing the cognitive neural mechanism of duration perception. Duration aftereffect has received more and more attention in recent years. In this review, we introduce recent research advances in our understanding of duration aftereffect, especially with regards to its manifestations, origin, and cognitive neural mechanisms. We also propose possible directions for future research. In sum, we posit that studies on the duration aftereffect phenomenon are helpful in understanding general duration perception, and as such, should receive more attention in future.
Figural Aftereffect ; Humans ; Motion Perception ; Visual Perception

To extract the temporal structure of sensory inputs is of great significance to our adaptive functioning in the dynamic environment. Here we characterize three types of temporal structure information, and review behavioral and neural evidence bearing on the encoding and utilization of such information in visual and auditory perception. The evidence together supports a functional view that the brain not only tracks but also makes use of temporal structure from diverse sources for a broad range of cognitive processes, such as perception, attention, and unconscious information processing. These functions are implemented by brain mechanisms including neural entrainment, predictive coding, as well as more specific mechanisms that vary with the type of temporal regularity and sensory modality. This framework enriches our understanding of how the human brain promotes dynamic information processing by exploiting regularities in ubiquitous temporal structures.
Attention ; Auditory Perception ; Brain ; physiology ; Humans ; Time Perception ; Visual Perception

The core of visual processing is the identification and recognition of the objects relevant to cognitive behaviors. In natural environment, visual input is often comprised of highly complex 3-dimensional signals involving multiple visual objects. One critical determinant of object recognition is visual contour. Despite substantial insights on visual contour processing gained from previous findings, these studies have focused on limited aspects or particular stages of contour processing. So far, a systematic perspective of contour processing that comprehensively incorporates previous evidence is still missing. We therefore propose an integrated framework of the cognitive and neural mechanisms of contour processing, which involves three mutually interacting cognitive stages: contour detection, border ownership assignment and contour integration. For each stage, we provide an elaborated discussion of the neural properties, processing mechanism, and its functional interaction with the other stages by summarizing the relevant electrophysiological and human cognitive neuroscience evidence. Finally, we present the major challenges for further unraveling the mechanisms of visual contour processing.
Cognition ; Form Perception ; Humans ; Visual Cortex ; physiology ; Visual Perception

The human visual system efficiently extracts local elements from cluttered backgrounds and integrates these elements into meaningful contour perception. This process is a critical step before object recognition, in which contours often play an important role in defining the shapes and borders of the to-be-recognized objects. However, the neural mechanism of the contour integration is still under debate. The investigation of the neural mechanism underlying contour integration could deepen our understanding of perceptual grouping in the human visual system and advance the development of the algorithms for image grouping and segmentation in computer vision. Here, we review two theoretical frameworks that were proposed over the past decades. The first framework is based on hardwired horizontal connection in primary visual cortex, while the second one emphasizes the role of recurrent connections within intra- and inter-areas. At the end of review, we also raise the unsolved issues that need to be addressed in future studies.
Form Perception ; Humans ; Models, Neurological ; Pattern Recognition, Visual ; Visual Cortex ; physiology ; Visual Perception

We examined whether visual perception related to consumption norms could influence food consumption and satiety by using modified soup bowls with elevated bottoms. Twenty-six healthy women (BMI 19.9 kg/m2 Age 24 yr) participated in the study once a week for 2 weeks. The subjects were served beef shank soup in one of two soup bowls (180 g soup in the modified bowl or 250 g soup in the normal bowl). The results showed that subjects who ate from the modified soup bowl consumed less soup (135.3 kcal vs 180.0 kcal, P<0.001) and had lower total energy intake (390.6 kcal vs 438.1 kcal, P<0.01) than those who ate from the normal soup bowl. However, despite consuming fewer calories, satiety levels of those who ate from the modifed soup bowl were not significantly different from those using the normal soup bowl. In conclusion, these results indicate that the modified soup bowl which created a distorted visual perception ot the amount of soup in the bowl leads to decreased soup intake and total energy intake without altering satiety. The reduced amount of soup in the modified soup bowl may also implicitly suggest what might be interpreted as an appropriate amount to consume, and also in essence suggest reduced consumption norm.
Energy Intake ; Female ; Humans ; Visual Perception

PURPOSES: To evaluate the effect of cycloplegia on the visual acuity and stereopsis according to the refraction and age. METHODS: This study included 112 eyes of 56 patients, which were divided into three groups according to the refraction. The best corrected visual acuity and stereopsis were compared between without and with cycloplegia in all groups according to age. RESULTS: After cycloplegia, at near, naked visual acuity decreased in 0.53 logMAR, average and stereopsis also deceased from 93 seconds to 343 seconds. At far, the naked and best corrected visual acuity had less decreased than near visual acuity. At near, there was no significant difference on the degree of decreased visual acuity and stereopsis according to refraction, but in emmetropic patients, the visual acuity at near significantly decreased. Patients younger than ten years old had more decreased visual acuity at near compared with older than forty-five years old. CONCLUSIONS: After pupil dilatation, there significant decreased near visual acuity and stereopsis, there was little change at far. The degree of decreased vision was different according to the refraction and age, therefore it would be helpful to explain the anticipating result.
Depth Perception* ; Dilatation ; Humans ; Pupil ; Visual Acuity

OBJECTIVE: The aim of this study was to investigate relationships between cognitive impairment and functional outcomes in stroke patients with spatial neglect. METHOD: Twenty seven right hemisphere ischemic stroke patients who admitted to an inpatient rehabilitation unit were included. Patients were divided into two group based on KF-NAP scores: Neglect group (n=18) and non-neglect group (n=9). Neglect group (n=18) were subdivided into two groups by discharge FIM scores as poor outcome group (n=8, <70) and good outcome group (n=10, ≥70). Cognitive function assessments including attention (Attention & Calculation, Digit span test-Forward), memory (Digit span test-Backward, SVLT-Immediate recalls/Delayed recalls) and visual perception (LOTCA-Visual perception/Visuomotor organization), and stroke severity assessment including NIHSS, FMA, K-MMSE, and FIM were performed. Cognitive impairments and functional outcomes were compared between two groups. RESULTS: There were significant differences in NIHSS, FMA (affected U/E, affected L/E), discharge FIM, FIM gain and LOTCA-visuomotor organization between Neglect group and non- neglect group (p<0.05). Among the patients with spatial neglect, there were significant differences in KF-NAP, K-MMSE and assessment scores of memory and visual perception between poor outcome group and good outcome group. Attention, memory and visual perception were significantly correlated with KF-NAP scores (p<0.05). CONCLUSION: Stroke patients with spatial neglect showed more severe impairment in cognitive, motor and general functional status, which resulted in delayed functional recovery. Spatial neglect patients with combined memory and visual perception impairment may show poor functional outcome.
Humans ; Inpatients ; Memory ; Rehabilitation ; Stroke* ; Visual Perception

OBJECTIVE: To investigate the effect of computer-based cognitive rehabilitation on unilateral spatial neglect in stroke patients. METHOD: Twenty four stroke patients (7 men, 17 women) who had unilateral spatial neglect were recruited. Patients were randomly assigned to either case or control group. Case group received both classical neglect stimulation therapy (attention and compensation training) and computer-based cognitive rehabilitation, but control group received only classical neglect stimulation therapy. The effect of therapy was assessed with star cancellation test, line bisection test, MVPT (motor-free visual perception test), and MBI(modified Barthel index). RESULTS: Four weeks after the therapy, both group showed significant improvement in star cancellation test, line bisection test, MVPT, and MBI. But there was no statistically significant difference between control and case group with each evaluation tool after 4 weeks treatment (p>0.05). CONCLUSION: Computer-based cognitive rehabilitation has no additional benefit to the treatment of hemi-spatial neglect in stroke patients.
Compensation and Redress ; Humans ; Male ; Stroke ; Visual Perception

Because of a limited capacity of information processing in the brain, the efficient processing of visual information requires selecting only a very small fraction of visual inputs at any given moment in time. Attention is the main mechanism that controls this selection process, namely selective attention. Selective attention is the mechanism by which the subset of incoming information is preferentially processed from the complex external environment. Research on selective attention has two key issues. One is what targets (inputs) are selected by attention. There are three different types of selective attention according to its selected target: space-based, feature-based, and object-based attention. Another issue is how selective attention is generated. There are two different types of selective attention according to its generating source: top-down and bottom-up attention. In this review, these two issues are introduced to systematically discuss the neural mechanism of visual selective attention.
Attention ; Brain ; physiology ; Cognition ; Humans ; Visual Perception