Abstract
urpose: : We showed previously that geostatistical methods constitute a promising tool to assess the spatial distribution of visual attention (Canto–Pereira et al., ARVO 2005 # 5653). In the present study, we investigated the anisotropic patterns of spatial visual attention under different tasks.
Methods: : Reaction times (RTs) to visual stimuli were measured monocularly in 20 normal participants. Stimuli and RTs were provided by the software E–Prime v 1.1 (PST Inc.) using a 19" monitor driven by a 10 bit graphics board (refresh rate 100 Hz, resolution of 800 x 600). Two different conditions were employed: in experiment 1 participants were asked not to attend to any particular region, but rather try to spread their attention as uniformly as possible over the computer screen (diffused attention) whereas in experiment 2 they were instructed to direct their attention toward the center of the computer screen coincident with the fixation point (overt attention).
Results: : In experiment 1, 2D maps obtained through ordinary kriging (an interpolation method of geostatistical analysis) showed an attentional inferonasal advantage. Experiment 2 showed that participants indeed focused their attention toward the center of the screen, with spatial distribution similar to the topography of cone distribution of the human retina (Curcio et al. 1990).
Conclusions: : An anisotropic pattern in the distribution of visuo–spatial attention was clearly evident under a diffuse attention situation; whereas in an overt attention situation, participants were able to focus their attention in a specific area of the computer screen.
