Abstract
Both space- and object-based attention facilitate the selection of relevant information within the visual environment. Utilizing the classic Egly task, Fiebelkorn, Saalmann & Kastner (2013) recently demonstrated a temporal relationship between both visual attention mechanisms, whereby periods of peak target detection at cued and uncued locations within an attended object share a common 8 Hz frequency with offset phases. We set out to investigate whether the observed sampling rate would be fixed across a range of task conditions, or if instead it is under strategic control. We first extended the observation of consistent sampling rates at within-object locations to a challenging target discrimination task relying on an endogenous spatial cue with 80% validity. On the remaining 20% of trials, the spatial cue was equally likely to appear in an invalid location on the same object, or an invalid location on a different (equidistant) object. Across all trial types, within-subject target discrimination accuracy was constrained to fall between 55-75%. A variable cue-to-target interval ranging from 300 – 1175 ms was used to allow for spectral analysis of the hit rate at each target location over time. Consistent with a large body of literature on space-based attention, response times were faster in the valid condition relative to the invalid conditions. However, an analysis of the hit rates did not produce space- or object-based attention effects of the magnitude previously reported. Nonetheless, the frequency analysis revealed a periodic reweighting of attention at both within-object locations at approximately 8 Hz. This suggests that the rhythmic sampling reported in the previous research may be robust against certain changes in task demands and performance. Ongoing research aims to test whether the periodicity of space- and object-based attention effects may be modulated by manipulating the behavioral relevance of each location.
Meeting abstract presented at VSS 2017