Abstract
Can spatial attention increase the amount of adaptation even when the adaptor was invisible? Kanai et al. (2006) showed that spatial attention could not modulate the amount of tilt aftereffect when the adaptor was invisible. In this study, we asked the same question but used different methods. The period of adaptation was longer and the contrast-decrement detection task was used to modulate participants' attention. We first measured contrast thresholds of a sine grating for each participant using QUEST method. We then had participants adapt to the gratings with the same spatial frequency and orientation. The two adaptors were presented in the left and the right visual field of a non-dominant eye and they were made to be invisible using binocular rivalry. They were suppressed by two pinwheel gratings presented in a dominant eye. The duration of perceiving adaptors was less than 3% of the entire adaptation period. Initial adaptation period was 1 minute and adaptation was maintained by 5 second top-up. To modulate attention during adaptation, participants performed the contrast-decrement detection task on one of the two pinwheel gratings (suppressors). Participants asked to report occurrences of contrast decrements in one of the two pinwheel gratings. Contrast decrements were independently occurred in each visual field regardless of participants' locus of attention. The contrast threshold in the attended field was elevated significantly more than that in the unattended field. However, this trend was not observed in the yoking condition in which the two adaptors were not presented during adaptation. Note that participants' percept was the same in this condition as in the adaptors-present condition because only pinwheel gratings were perceived even when adaptors were present. These results suggest that spatial attention can modulate the effect of adaptation even when the adaptor is invisible.
This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (No.M10644020001-06N4402-00110).