Sensitivity and criterion effects in the spatial cuing of visual attention.

Abstract

This study is concerned with three questions about the role of attention in peripheral detection: (1) Is the increased detection rate for spatial locations with high probabilities of target occurrence assigned to them due to sensitivity or criterion effects? (2) Does the effect of spatial cuing (probabilistic priming) require different explanations for letter detection and detection of luminance increments (Shaw, 1984)? (3) Can attention be shared between two separate locations cued to be most likely (Posner, Snyder, & Davidson, 1980)? These questions were investigated in two experiments, both using a signal detection plus localization task (rating method). In Experiment 1 (symbol detection), single or double cues indicating one or two most likely locations (three or two least likely locations) were presented. Introducing the second cued location resulted in a marked sensitivity gain for this position, relative to uncued locations in the single-cue condition. Decision criteria were more liberal for cued and more conservative for uncued locations. In Experiment 2, a luminance increment (single target probe) and two symbol detection (target plus distractors) tasks were compared. For symbol detection, there was a marked priming effect; but for luminance detection, cued locations showed no advantage in sensitivity. However, all tasks showed differential criterion setting for cued and for uncued locations. These results suggest that letter detection is capacity limited, whereas luminance increment detection is not, and furthermore, that decision criteria are largely preset according to a priori target probabilities assigned to particular locations.