Perception: ECVP 2002 abstracts

ECVP 2002 abstract

Shifts in feature-based attention as a result of spatial cueing: support for location dominance in attentional selection
Z M Hafed, J J Clark (Centre for Intelligent Machines, McGill University, 3480 University Street, Montréal, Québec H3A 2A7, Canada; e-mail:

Recent studies on the different modes of attentional selection have suggested that feature-based attention may be mediated by spatial location. Here we provide evidence that supports this idea, and we investigate a possible time course for such mediation. We designed psychophysical tasks to study whether a shift in spatial attention gives rise to a shift in feature-based attention towards the features present at the attended location. In one experiment, subjects looked at a central square that disappeared 200 ms after trial onset. After a gap of 200 ms, a peripheral square appeared 17 deg to the right or left of fixation and acted to capture spatial attention. The peripheral square was extinguished 150 ms later, after which a second foveal square appeared for 50 - 150 ms. Subjects maintained fixation and compared the colours of the two foveal squares regardless of the colour of the peripheral one. We found that the colour of the peripheral square influenced colour perception at fixation, with the effect being strongest approximately 100 ms after the onset of the final foveal square. When the peripheral square was replaced with a parafoveal ring to avoid any explicit summoning of spatial attention, no similar effect seemed to occur.

© 2002 Pion Ltd