Abstract
Top-down attentional sets instantiate a filter used to search for target feature(s) of interest in rich environmental contexts. Evidence suggests that top-down sets sometimes modify under certain conditions but the pressures causing these adjustments are poorly understood. Here, we examined whether context can drive top-down set plasticity by manipulating the proportion of key colored distracters in a contingent attention capture paradigm. We presented subjects three rapid serial visual presentation (RSVP) streams of colored letters, one central (target stream) and one to either side (two distracter streams), and asked them to identify a red letter within the, otherwise heterogeneous, target stream. The, otherwise homogenous, distracter streams contained four types of letters: neutral colored (gray), target colored, non-target colored (a color singleton), or threshold colored (determined via individual subject staircase tracking 75% difference threshold from target color). Our critical manipulation varied the proportion of four distracter types in the following three conditions: (1) equal occurrence of threshold (16.6%) and target (16.6%) colored distracters, (2) double occurrence of threshold (22%) versus target (11%) colored distracters, or (3) one-half occurrence of threshold (11%) versus target (22%) colored distracters. Neutral (50%) and non-target (16.6%) colored distracter proportions were fixed. If proportional context affects the plasticity of top-down sets, this will be reflected as a difference in threshold distracter accuracy between the two unequally proportioned conditions (conditions 2 & 3 above). Alternatively, if top-down sets are unaffected by proportional context, threshold distracter accuracy in these conditions should match that of the equally proportioned condition (condition 1). Results were consistent with the former prediction: threshold colored distracters captured attention differentially in conditions 2 versus 3. Thus, a simple change in the proportion of colored distracters led to a significant alteration of the top-down set, providing evidence that proportional context does, indeed, lead to top-down set plasticity.
Meeting abstract presented at VSS 2017