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

Many applications in virtual reality and telerobot call for the implementation of displaying the human softness haptics on the object being touched. Although there are lots of literatures on discrimination threshold for displacement, force magnitude, shape and viscosity, there is still a lack of research on remembrance of softness haptic perception in human fingertips. Such research is needed in designing haptic rendering and display system. In this paper, a novel softness haptic display device based on deformable length of elastic element control was adopted as a test device to study the human fingertip's ability of remembrance of softness haptic perception. According to the recall experiment and recognition experiment, the softness haptic memory span and reaction time were discussed. From the experimental results, some important conclusions have been obtained: (1) human softness haptic memory span is 3 to 4 items, which is smaller than visual memory span and auditory memory span; (2) it is more difficult for people to remember hard objects than soft objects.
Adult ; Female ; Form Perception ; physiology ; Humans ; Male ; Mental Recall ; Touch ; 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

OBJECTIVES: Schizophrenic patients have been reported to be associated with abnormal performance on a broad range of neuropsychological tests. But it has been a persistent controversy in the neuropsychology of schizophrenia whether this disorder is characterized by generalized deficits or specific deficits. The purpose of this study was to investigate, using standardized Benton Neuropsychological Assessment(BNA), whether the specific pattern of neurocognitive deficits is found in schizophrenics. METHODS: The subjects were composed of (1) 30 schizophrenic inpatients who were diagnosed as paranoid subtype according to DSM-IV diagnostic criterior and (2) 30 normal subjects with matching demographic variables(i.e. age, sex, educational level). All tests of BNA were given to schizophrenic patients and normal subjects, and the performances of schizophrenic patients and normal subjects were compared on all aspects of BNA. Schizophrenic symptoms were assessed via Positive and Negative Syndrome Scale(PANSS) to determine the relationship between clinical symptoms and schizophrenic cognitive deficits. RESULTS: Of 12 tests of BNA, schizophrenic patients' performances on Serial Digit Learning(SDL), Facial Recognition Test(FR), Tactile Form Perception(TFP), Finger Localization(FL) were significantly lower than those of normal subjects. In addition, schizophrenic patients showed significantly lower performances than those of normal subjects on Right Hand, Left Hand, Identification of two simultaneously touched fingers of FL, and more Peripheral Error on Visual Form Perception Test(VFPT). Finally, no significant correlation was found with respect to the relationships between total scores, positive symptom scores, negative symptom scores of PANSS, and all scores of BNA tests in schizophrenic patients. CONCLUSION: These results suggest that schizophrenic patients may have a specific pattern of neurocognitive deficits in verbal working memory, learning, attention, and complex sensory information processing in visual and haptic modality such as facial perception skills, tactile information processing, independent of psychotic symptoms. The pattern of deifcits is at least in partial, in agreement with many previous study results. On the tests of linguistic functions, visuospatial perception, and constructional abilities, schizophrenic patients' performances were not significantly different from those of normal subjects. The findings on visuospatial perception and constructional abilities imply that some posterior cortical zones may be relatively uncompromised in schizophrenia. Both poor performances on object recognition tests relative to normal performances on object location tests and verbal working memory dysfunction may be associated with the putative dysfunction of the reciprocal connections either (1) between the prefrontal and parietal cortex or (2) between the prefrontal cortex and hippocampal formation. This tentative explanation remains to be confirmed.
Automatic Data Processing ; Diagnostic and Statistical Manual of Mental Disorders ; Fingers ; Form Perception ; Hand ; Hippocampus ; Humans ; Inpatients ; Learning ; Linguistics ; Memory, Short-Term ; Neuropsychological Tests ; Neuropsychology ; Prefrontal Cortex ; Rabeprazole ; Schizophrenia*

The method of event-related potentials (ERP) was used to study the gender difference in face recognition. The stimuli in the experiment were 10 upright and 10 inverted face photos. The subjects, half female and half male, were asked to judge whether the face was upright or inverted. The results showed that the N170 wave forms were observed in the occipito-temporal regions and they were found exhibiting brain's right hemispheric dominance. The stimuli of different gender photos were noticed to have no significant impact on the N170 wave forms, but there were significant differentce in the amplitude and latency period of N170 between different gender participants. Moreover, there was marked difference in the latency period of the male participants watching the same gender face and different gender face. Similar results were not found in the ERP's latency period of female participants.
Adult ; Brain ; physiology ; Electroencephalography ; Evoked Potentials ; Face ; Facial Expression ; Female ; Form Perception ; physiology ; Humans ; Male ; Pattern Recognition, Visual ; physiology ; Recognition (Psychology) ; Sex Factors ; Young Adult

The process of reading words depends heavily on efficient visual skills, including analyzing and decomposing basic visual features. Surprisingly, previous reading-related studies have almost exclusively focused on gross aspects of visual skills, while only very few have investigated the role of finer skills. The present study filled this gap and examined the relations of two finer visual skills measured by grating acuity (the ability to resolve periodic luminance variations across space) and Vernier acuity (the ability to detect/discriminate relative locations of features) to Chinese character-processing as measured by character form-matching and lexical decision tasks in skilled adult readers. The results showed that Vernier acuity was significantly correlated with performance in character form-matching but not visual symbol form-matching, while no correlation was found between grating acuity and character processing. Interestingly, we found no correlation of the two visual skills with lexical decision performance. These findings provide for the first time empirical evidence that the finer visual skills, particularly as reflected in Vernier acuity, may directly contribute to an early stage of hierarchical word processing.
Adolescent ; Decision Making ; Female ; Form Perception ; physiology ; Humans ; Male ; Pattern Recognition, Visual ; physiology ; Photic Stimulation ; Reading ; Semantics ; Statistics as Topic ; Visual Acuity ; physiology ; Vocabulary ; Young Adult

OBJECTIVE: To investigate the mechanism of myopia following intravitreous injection of MK801 (dizocipine maleate) intravitreous injected. METHODS: Three-week-old guinea pigs were divided into six groups: group A (control), group B (3 weeks form-deprivation in right eye), group C ( 3 weeks form-deprivation in right eye + saline), group D (3 weeks form-deprivation in right eye + MK801 1ng), group E (3 weeks form-deprivation in right eye + MK801 10 ng), group F (3 weeks form-deprivation in right eye + MK801 100 ng). The refraction and axial length of the eyes were measured. ncNOS was measured by hybridization in situ, and cyclic GMP (cGMP) concentrations by radioimmunochemistry. The correlation between MK801 concentration and diopter degree, axial length of the eyes, and levels of ncNOS or cyclic GMP were analyzed with linear correlation in the groups C-F. RESULTS: Diopter degree was decreased, axial eye length was shorted and levels of ncNOS and c-GMP were decreased in groups C, D, E and F dependent on the concentration of MK801. The diopter degree had positive correlation with MK801 concentration (r=0.702, P<0.05), while the axial eye length and the levels of ncNOS and cGMP were negatively correlated (r=-0.736, -0.637, -0.725, P<0.05) CONCLUSION MK801 injected into the vitreous humor can restrain myopia by down-regulated the expression of the nitric oxide-cyclic GMP signaling pathway. The effect is concentration dependent.
Animals ; Cyclic GMP ; metabolism ; Dizocilpine Maleate ; administration & dosage ; pharmacology ; Down-Regulation ; Female ; Form Perception ; physiology ; Guinea Pigs ; Injections, Intraocular ; Male ; Myopia ; physiopathology ; Nitric Oxide Synthase Type I ; metabolism ; Sensory Deprivation ; physiology ; Signal Transduction ; drug effects ; Vitreous Body ; drug effects

Objective: To compare the visual performance and patient-reported outcomes of three types of monofocal intraocular lenses (IOL) with different asphericities. Methods: This cross-sectional, comparative study comprised of 62 pseudophakic eyes divided into three groups corresponding to the IOL that they were previously implanted with (Tecnis ZCB00 negative aspheric IOL, EnVista MX60 neutral aspheric IOL and Akreos Adapt spheric IOL). Mean refractive spherical equivalent (MRSE), best-corrected far visual acuity (BCVA), spherical aberration (SA), contrast sensitivity (SC), halo and starburst, and responses to a qualitative questionnaire (NEI-RQL) were measured. Results: There was no significant difference in MRSE (P=0.74) and BCVA (P=0.52) among the three groups. There was a statistically significant difference (P=0.00) in mean internal (lens) SA, measured through a 5mm pupil, among Tecnis (-0.150 μm), EnVista (+0.022 μm) and Akreos Adapt (+0.094 μm). Compared to the Akreos Adapt, the Tecnis and EnVista groups had significantly better CS at 6 CPD and 12 CPD under mesopic testing without glare (P= 0.01) and at 6 CPD mesopic testing with glare (P=0.04). Halo scores were insignificant among the three groups. However, starburst scores were significantly worse in the Akreos Adapt IOL than the Tecnis and EnVista (P=0.01). There was no difference in questionnaire responses among the three groups. Conclusion The negative aspheric and neutral aspheric lenses showed significantly lower SA resulting in better CS in mesopic conditions and better starburst scores. MRSE, BCVA and subjective satisfaction were statistically similar regardless of the type of monofocal intraocular lens
Contrast Sensitivity

The effect of illumination on the contrast sensitivity function was studied using an Arden Contrast Sensitivity System and incandescent electric lamp. The intensities of illumination were set at 50,100,200,500, and 1,000 lx. The contrast sensitivity function was saturated at 500 lx of illumination in both monocular and biocular condition. But frequency charicteristics showed that the CSF was increased more at 1,000 lx of illumination at high frequency.
Contrast Sensitivity* ; Lighting*

PURPOSE: To assess visual acuity, spherical aberration and contrast sensitivity in patients who were implanted with spheric, aspheric ReSTOR(R) or Crystalens HD(R) lenses. METHODS: The present study enrolled 16 patients (32 eyes) implanted with biliateral spheric ReSTOR(R) (four patients, spheric ReSTOR group), bilateral aspheric ReSTOR(R) (seven patients, aspheric ReSTOR group) or bilateral Crystalens HD(R) (five patients, Crystalens HD group) lenses. At three months postoperatively, visual acuity, spherical aberration, and contrast sensitivity were evaluated. RESULTS: Three months after surgery, there were no significant differences in uncorrected distant or intermediate visual acuity among the three groups. Uncorrected near visual acuity in the spheric and aspheric ReSTOR groups was superior to that in the Crystalens HD group, and the aspheric ReSTOR group had less spherical aberration. Mesopic contrast sensitivity in the Crystalens HD group was significantly higher at three cycles per degree compared to those in the spheric and aspheric ReSTOR groups. CONCLUSIONS: Uncorrected near visual acuity in the Crystalens HD group was inferior to those in the spheric and aspheric ReSTOR groups, but the mesopic contrast sensitivity of the Crystalens HD group at three cycles per degree was superior to those in the spheric and aspheric ReSTOR groups.
Contrast Sensitivity ; Humans ; Visual Acuity