, , ,

Touch disambiguates rivalrous perception at early stages of visual analysis,Curr Biol, 4 (20), R143-144.

Touch disambiguates rivalrous perception at early stages of visual analysis,Curr Biol, 4 (20), R143-144. 

Download

Binocular rivalry is a powerful tool to study human consciousness: two equally salient stimuli are imaged on the retinae, but at any given instant only one is consciously perceived, the other suppressed.The suppression takes place early, probably in V1. However, a trace of the suppressed signal has been detected along the dorsal visual pathway (BOLD responses) and demonstrated with psychophysical experiments. The suppressed image of a rotating sphere during rivalry is restored to consciousness when the observer actively controls the rotation and a similar effect on the suppressed signal has been shown for motion perception and reflexive eye movements (see Supplemental References). Here, we asked whether cross-modal sensory signals could selectively interact with rivalrous visual signals that are analyzed at a very early stage, probably V1. An auditory stimulus, when attended, can influence binocular rivalry, extending dominance times for a congruent visual stimulus. Tactile information can  also disambiguate unstable visual motion and can fuse with vision to improve discrimination (e.g. slant). Our results indicate that a haptic oriented stimulus can disambiguate visual perception during binocular rivalry of gratings of orthogonal orientation, not only by prolonging dominance but also by curtailing suppression of the visual stimulus of matched orientation. The effect is selective for the spatial frequency of the stimuli, suggesting that haptic signals interact with early visual representations to enhance access to conscious perception.

, , ,

Saccades compress space, time and number,Trends Cogn Sci, 12 (14), 528-533.

Saccades compress space, time and number,Trends Cogn Sci, 12 (14), 528-533. 

Download

It has been suggested that space, time and number are represented on a common subjective scale. Saccadic eye movements provide a fascinating test. Saccades compress the perceived magnitude of spatial separations and temporal intervals to approximately half of their true value. The question arises as to whether saccades also compress number. They do, and compression follows a very similar time course for all three attributes: it is maximal at saccadic onset and decreases to veridicality within a window of approximately 50ms. These results reinforce the suggestion of a common perceptual metric, which is probably mediated by the intraparietal cortex; they further suggest that before each saccade the common metric for all three is reset, possibly to pave the way for a fresh analysis of the post-saccadic situation.

, , ,

Temporal auditory capture does not affect the time course of saccadic mislocalization of visual stimuli,J Vis, 2 (10), 7 1-13.

Temporal auditory capture does not affect the time course of saccadic mislocalization of visual stimuli,J Vis, 2 (10), 7 1-13. 

Download

Irrelevant sounds can “capture” visual stimuli to change their apparent timing, a phenomenon sometimes termed “temporal ventriloquism”. Here we ask whether this auditory capture can alter the time course of spatial mislocalization of visual stimuli during saccades. We first show that during saccades, sounds affect the apparent timing of visual flashes, even more strongly than during fixation. However, this capture does not affect the dynamics of perisaccadic visual distortions. Sounds presented 50 ms before or after a visual bar (that change perceived timing of the bars by more than 40 ms) had no measurable effect on the time courses of spatial mislocalization of the bars, in four subjects. Control studies showed that with barely visible, low-contrast stimuli, leading, but not trailing, sounds can have a small effect on mislocalization, most likely attributable to attentional effects rather than auditory capture. These findings support previous studies showing that integration of multisensory information occurs at a relatively late stage of sensory processing, after visual representations have undergone the distortions induced by saccades.