The Influence of Target and Distractor Location Bias on Oculomotor Capture and Distractor Dwell Times

摘要

When the location of a search target is more likely to appear on one side of the display, observers initiate search to that side more often and more quickly (Jones & Kaschak, in press). Moreover, the rate of initial saccades to the biased side of the display is elevated even when a clearly marked target appears on the unbiased side (Jones & Kaschak, in preparation). These results provide clear evidence that 1) participants are sensitive to and learn such biases and 2) the resulting expectations about target location compete with the visual signal for control of eye-movements. The current work explores the interaction between internal (i.e., cognitive) and external (i.e., sensory) information about likely and actual stimulus locations. We pitted target bias against abrupt distractor onsets in the oculomotor capture paradigm (Theeuwes et al., 1998). On one hand, expectations about likely target locations might buffer against capture by an abrupt onset distractor. On the other hand, if location expectations bias participants to allocate attentional resources to a specific region of a search display, this could lead to increased capture when the distractor appears in that region. We orthogonally manipulated target and distractor location bias in a task in which observers searched for a color singleton in the presence of an onset distractor. Results indicate that, in fact, both outcomes obtain depending on the bias condition and location of target and distractor on a given trial. While bias influenced the likelihood of capture, it did not modulate dwell time on the distractor when the eyes were captured. Results are not consistent with theories of capture that posit top-down modulation only with respect to dwell time after capture has occurred.