Abstract
Objective:’Prior-entry’ refers to objects at attended locations being perceived prior to those at unattended locations (e.g., Shore et al., 2001; Schneider & Bavelier, 2003). Our goal: investigate prior-entry for objects of the attended feature (color).
Methods:Three experiments employed temporal order judgment (TOJ) or simultaneity judgment (SJ). Stimuli comprised two oriented bars equidistant from a fixation mark. One bar was presented prior to the other; stimulus-onset asynchrony (SOA) between them varied. TOJ task: report orientation of the bar shown first; SJ task: report if bars were shown simultaneously. In Experiment 1, location or feature (color) cues preceded stimuli by brief (110 ms) cue lead time (CLT). Observers performed TOJ task, not attending to cue. In Experiments 2 and 3, effect of feature cue was examined further by engaging attention to cue's color. Three CLT conditions (250, 700, 1200 ms) were used in Experiment 2 (TOJ paradigm), and one CLT condition (700 ms) in Experiment 3 (SJ paradigm). Note: TOJ task involved reporting orientation of first bar, and orientation feature is orthogonal to color feature, thus minimizing first-order response bias.
Results:Spatial prior-entry effect was replicated in Experiment 1: bar at cued position was perceived earlier than bar at uncued position. Feature-based prior-entry effect was observed only in Experiment 2 for CLTs of 700 and 1200 ms: bar of attended color was perceived earlier than that of unattended color.
Conclusions:Prior-entry effect for object with attended feature was found in TOJ task, the most frequently used paradigm in the literature to claim the spatial prior-entry effect, but the effect was absent in the SJ task. This could be due to a second-order response bias in the TOJ task, or to the fact that the SJ task is not as sensitive as the TOJ task.