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A feature-tracking model simulates the motion direction bias induced by phase congruency,J Vis, 3 (6), 179-195.

A feature-tracking model simulates the motion direction bias induced by phase congruency,J Vis, 3 (6), 179-195.

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Here we report a new motion illusion where the prevailing motion direction is strongly influenced by the relative phase of the harmonic components of the stimulus. The basic stimulus is the sum of three sinusoidal contrast-reversing gratings: the first, the third, and the fifth harmonic of two square wave gratings that drift in opposite direction. The phase of one of the fifth components was kept constant at 180 deg, whereas the phase of the other fifth harmonic was varied over the range 0-150 deg. For each phase value of the fifth harmonic, the motion was strongly biased toward its direction, corresponding to the direction with stronger phase congruency between the three harmonics. The strength of the prevailing motion was assessed by measuring motion direction discrimination thresholds, by varying the contrast of the third and the fifth harmonics plaid pattern. Results show that the contrast of high harmonics had to be increased by more than a factor of 10, to achieve a balance of motion for phase differences greater than 60 deg between the 2 fifth harmonics. We also measured the dependence on the absolute phase of harmonic components and found that it is not an important parameter, excluding the possibility that local luminance cues could be mediating the effect. A feature-tracking model based on previous work is proposed to simulate the data. The model computes local energy function from a pair of space-time separable front stage filters and applies a battery of directional second stage mechanisms. It is able to simulate quantitatively the phase congruency dependence illusion and the insensitivity to overall phase. Other energy models based on directional filters fail to simulate the phase congruency dependency effect.

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On the Possibility of a Unifying Framework for Serial Dependencies, i-Perception, 6(6) 1–16.

On the Possibility of a Unifying Framework for Serial Dependencies, i-Perception, 6(6) 1–16.

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erial effects in perception have been studied since the dawn of psychophysics. Color aftereffects greatly advanced the understanding of color vision in the 19th century, and motion aftereffects have intrigued perceptual scientists for centuries. Recent discoveries in visual attention and psychophysics have intensifed interest in such effects. The current consensus is that they are not curiosities but serve an important function and can be critical for understanding perception.
The current article summarizes the contributions to a recent conference (SFX 2014, Pisa, Italy) and underscores the idea that the brain has learned how to exploit temporal regularities in the environment.

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Auditory attention at the onset of West syndrome: correlation with EEG patterns and visual function,Brain Dev, 5 (28), 293-299.

Auditory attention at the onset of West syndrome: correlation with EEG patterns and visual function,Brain Dev, 5 (28), 293-299.

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At the onset of West syndrome a specific impairment of visual function has been clearly demonstrated, while other aspects of sensorial development, and in particular of the auditory function, have been less studied. The aim of this study was to evaluate auditory function and orienting responses at the onset of West syndrome, and to relate the results with EEG patterns, visual function and neurodevelopmental competence. A prospective multicentric study was performed on 25 successively enrolled infants with West syndrome; all the patients underwent a full clinical assessment, including MRI and video-EEG, visual function and auditory orienting responses (AORs) as well as Griffiths’ developmental scales. The whole assessment performed at the onset of spasms (T0) was repeated after two months (T1). AORs resulted significantly impaired both at T0 and T1. At the onset of spasms a highly significant relationship of auditory attention with visual function and neurodevelopmental competence was shown in both cryptogenic and symptomatic forms, but it was no longer present after two months. Our results may suggest a possible pervasive effect of the epileptic disorder on sensory processing, associated to a deficit of neurodevelopment. Although we failed to show a significant correlation between auditory orienting responses and EEG patterns, some evidence seems to support at least partially an influence of the epileptic disorder per se on the genesis of the sensorial impairment. A longer follow up and a larger cohort will be useful for a better clarification of these findings.