Transparency and corrugated motion: the effect of spatial layout

BARRAZA, J. F.; MARTÍN, A.

Regensburg, Alemania

Conferencia; 32th European Conference on Visual Perception; 2009

p { margin-bottom: 0.21cm; } Recently, we showed that the spatial layout of a stimulus affects our ability to locate the border defined by two adjacent surfaces with different speeds.  However, this effect does not appear or is very weak when these two surfaces are seen in transparency. Why would the spatial layout affect differently these two cases of segmentation? Ordering to address this question, we present an experiment exploring the effect of the layout on corrugated motion: a stimulus that becomes transparent as the bars size containing the different speeds becomes smaller. We measured the speed increment necessary to discriminate between test (three square patches with a corrugated pattern of moving-random-dots with alternating horizontal bars containing two different speeds) and reference (three square patches containing a transparent pattern consisting in two populations of random-dots moving at the same two speeds used in the test). The patches were displayed at an eccentricity of 7º from fixation and could be at three different angular distances among them: 120º, 60º and 45º. Results show that increasing the angular distance reduces the speed difference necessary to perceive corrugation without affecting the spatial scale at which it occurs, which suggests that layout affects corrugated but not transparent stimulus.