Abstract
Goal: It is known that covert attention improves discriminability and accelerates the rate of visual information processing (Carrasco & McElree, 2001). In this study we used the speed-accuracy tradeoff (SAT) procedure to examine: (1) effects of perceptual learning in visual search, and (2) effects of transient attention on perceptual learning in visual search, by assessing discriminability and speed of information processing.
Methods: Naive observers performed a discrimination conjunction task (orientation x spatial frequency) in which either a peripheral cue, indicating the target location and onset, or a neutral cue, indicating only target onset, preceded the display. The target (2-cpd tilted Gabor) was presented amid distracters (4-cpd tilted and 2-cpd vertical Gabors), and appeared in one of 8 iso-eccentric locations. A response tone prompted observers to respond after various lags (40–1500 ms). To assess perceptual learning, at the end of 10 consecutive sessions (1/day), observers performed a transfer task in which the identity of the target and one type of distracter was switched (3-cpd tilted target among 2-cpd tilted and 3-cpd vertical Gabors).
Results & Conclusion: In both the neutral and attentional conditions, both discriminability and processing speed improved over time for visual search. This improvement was due to perceptual learning: In the transfer task, performance was impaired when compared to the initial performance levels in the original task. Exogenous attention leads to an initial benefit in discriminability and faster processing speed. Despite this initial advantage, over the course of experimental sessions, attention continues to improve performance more than the neutral condition. These findings suggest that observers' perceptual learning occurred because they processed the target preferentially while inhibiting the distracters, particularly in the attended condition.