The influence of attentional capacity limits on multiple target visual search

Capacity limits are fundamental to the understanding of human cognition. They play a role in occupational errors (e.g., missing a threat in an airport security check or a cancerous tumor in medical examinations) that can have calamitous consequences. Previous studies have documented increased errors for detecting subsequent targets after detecting an initial target (T1), both in space as in Subsequent Search Misses (SSMs), and in time as in the Attentional Blink (AB; occurs when a second target is within ~500ms of T1). In this thesis, I present 2 experiments examining whether attentional capacity limits contribute to SSMs, using an AB framework applied to visual search, and test whether a training paradigm previously claimed to increase capacity can reduce the error rate. In Experiment 1, I manipulated target salience, and found more SSM errors when T1 was high-salience than low-salience. The data replicated an AB-like effect in spatial search: the accuracy of detecting T2 decreased when T1 and T2 were fixated closely in time. I used these data to examine the role of capacity limits in this spatial AB by comparing the conditions when T1 was high-salience versus low-salience. The spatial AB was larger when T1 was high-salience than low-salience, suggesting that attentional capacity limits might contribute to multi-target search errors. In Experiment 2, I replicated the results of Experiment 1, and found that ~1hr training can reduce both the classic AB and the spatial AB, demonstrating the potential for training to increase accuracy in tasks requiring detection of rapid events, whether these are separated in time or spatially, in a self-directed visual search. Future efforts should explore this possibility of reducing real-world search errors.