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Former studies have suggested that schizophrenia and bipolar disorders (BPD) are associated with a deficiency in the magnocellular visual system. Nevertheless, these findings are still controversial. The aim of the present study is to analyze whether visual processing is affected in schizophrenia, BPD, and depression patients and to investigate whether these deficits are associated with symptoms severity, neuropsychological function and eye movements. Thirty psychiatric inpatients, with diagnoses of Schizophrenia, Depression, and Bipolar Disorder participated in the study. Symptoms severity was measured with Brief Psychiatric Rating Scales. Accuracy in motion and form perception was evaluated by motion and form coherence tests respectively. Smooth pursuit eye movements were measured with Eye Tribe infrared video-oculography system. Data were analyzed off-line to calculate gain, delay and maximum speed. The general cognitive abilities were tested by Raven's Matrices. Stroop Test and Attentive Matrix were used to assess attention and Digit Span Test for memory. Executive functions were evaluated using Tower of London test and a modified version of Wisconsin Card Sorting Test. All the scores were standardized according to age and gender. No significant differences emerged between psychiatric diagnostic groups concerning motion and form perception and eye movements parameters. When compared to the control group, patients showed impaired visual perception and higher delay and lower gain values. Linear regression analysis showed that motion perception performances were related significantly to general cognitive abilities, attention ability, executive functions and ocular motility and did not depend to symptoms severity. Form recognition was only related to executive functions. These preliminary findings confirm the hypothesis that visual perception deficits in psychiatric patients are related to cognitive impairment and oculomotor defects .

Children and adults can approximate numbers of items, compare these approximations, and perform approximate arithmetic operations via a non-symbolic, pre-linguistic system called the Approximate Number System (ANS). Studies using neuroimaging techniques demonstrated the role of the parietal cortex in decoding both non-symbolic and symbolic quantity. Although it has been proven that the parietal regions are involved also in visual processing such as coherence motion perception, little is known about the relationship between these visual processes and the ANS. The aim of this study is to investigate whether the acuity in the ANS is related to dorsal and/or ventral visual functions. A sample of sixty-five typical development children (age 6-10 years; 42 males and 23 females) took part in the experiment. ANS acuity was measured using a numerical discrimination task (Halberda et al., 2008) in which participants were briefly shown arrays of yellow and blue dots and had to identify the more numerous array; a motion coherence test and a form coherence test were applied to evaluate dorsal and ventral stream functions respectively. In the motion test participants were asked to detect the direction of moving dots, in the form test participants had to recognize a form created by spatially aligned dots. We found significant correlations between ANS acuity and motion perception ability (p=0.014) as well as form discrimination ability (p=0.047). More specifically, higher performance in the motion and form tests are related to higher ANS acuity. The effect size values show that the magnitude of the relationship with the ANS was higher for the motion (partial η2=0.09) than for the form coherence test (partial η2=0.06). These results demonstrate that both dorsal and ventral visual processing influence ANS acuity but that the association between ANS and dorsal stream processing is slightly stronger.

Visual functions have been widely investigated in patients with developmental disorders. This study aims to analyze the development of dorsal and ventral visual function in children with typical development, measured as motion and form discrimination abilities. A sample of 304 children (age: 4-12 years; 154 males) participated in the experiment. Non-verbal intelligence (Raven’s matrices), visual acuity (Lea test), motion perception (motion coherence test-MCT) and form recognition (form coherence test-FCT) were assessed. The MCT consists of 150 white dots on a black background moving coherently at a constant velocity in one of the eight directions (signal) or in a Brownian manner (noise). The task was to recognize the direction of the signal dots. The FCT consists of white dots (signal) composing one of eight possible forms through spatial alignment of the dots, the noise was created by non-aligned dots distorting the form. The task was to recognize the form. Difficulty was increased by reducing the dot coherence (signal/noise) from 100% (no noise) to 36% in five levels. MANOVA showed a significant increment of motion and form perception accuracy with age, steeper for form as compared to motion recognition. Both functions are influenced by noise but motion discrimination seemed to be less affected. While noise had a stronger effect on the younger children in the FCT (worse performance with noise in the youngest) no such age effect was found in MCT. Motion and form perception are related to general intelligence at different ages as well as to the visual acuity. These results confirm the slowness in development of dorsal function as compared to ventral function. Visuo-spatial attention, general intelligence and visual acuity mediate the visual functionality development.

Perceptual learning has been studied as a mechanism by which people automatically and implicitly learn. Alternatively, learning can occur explicitly mediated by conscious feed-back which controls and guides the subjects'(tm) performance. The aim of this study was to examine whether the explicit and implicit learning could produce different patterns of results in a visual motion discrimination task. We exposed 12 participants to four different sessions. A preliminary training session consisted of 120 trials of motion discrimination task repeated three times in different days to measure the explicit learning. The subject had to discriminate among 4 directions in motion test presented at 10% of coherence (considered as parathreshold). A pre-test in which the baseline was evaluated by the correct responses average in the motion discrimination task for each direction. The implicit learning session was tested using the classic paradigm of task-irrelevant perceptual learning (TIPL) (Seitz and Watanabe, 2003) in which learning was mediated by subliminally pairing one selected direction with specific targets of an unrelated training task. This phase consisted of 120 trials repeated 7 times in three days. After that a post-test similar to the pretest indicated the implicit learning effect. In the explicit learning the improvement is relatively poor and not significant. In the implicit learning the effect was clearly significant for the trained direction, while the subjects did not improve their performances in the other directions. These results of the stronger learning effect obtained in TIPL suggest that visual motion learning can benefit more from direct lower level processing then from mediated attention mechanisms related to explicit learning.