Abstract
It has been previously shown that task-irrelevant perceptual learning (TIPL) can occur for stimuli that are presented at a different spatial location from the attended task (Seitz and Watanabe, 2003). However, TIPL was found to be restricted to the same visual hemifield as that in which the attended task stimulus was presented (Nishina et al., VSS05). Here, we further investigated the spatial profile of the task-irrelevant learning around the attended location. During the training period, the participants performed an attentionally demanded letter identification task (rapid serial visual presentation, with SOA = 300 ms) presented at a single location, while subthreshold static Gabor patches with noise were presented at three different locations in the same visual hemifield. The orientations of the Gabor patches were temporally paired with the target or distractor letters in the letter task. The detection performance of Gabors was tested before and after a seven days of training in which a different stimulus was exposed at each location and orientation. The largest improvement was found for the Gabors presented in closest proximity to the letter task. The improvement was smaller at the intermediate location, and the smallest at the most distal location. Our data indicate that the learning of the unattended task-irrelevant visual feature strongly depends on the attended location, with a gradual attenuation according to the spatial distance between them. These results suggest that a learning signal that is spatially tuned to the attended task incidentally facilitates the learning of nearby-presented unattended visual features.
This research was supported by NSF BCS-0549036 and the National Institute of Information and Communications Technology (NICT).