Ava Mitra¹, Jeremy Wolfe^1,2, Injae Hong¹; ¹Brigham and Women's Hospital, ²Harvard Medical School

In visual search tasks in the lab, participants are typically required to perform blocks of the same type of search tasks repeatedly (e.g., find a T among Ls). In real-world searches, however, you look for your keys, then your jacket, then the doorknob, and so on. You rarely search for your keys 100 times in a row. Real-world searches can offer a degree of choice that is not typically a feature of laboratory tasks (i.e., what do I want to look for next?). For instance, given a worklist of cases, should a radiologist be allowed to determine the order in which they are read? The current study aimed to investigate whether search performance, especially reaction time (RT) and miss rate, would be affected by manipulations of trial ordering and participants’ choice. Fifty observers completed 100 trials of each of four search tasks: T among Ls, a shape search for bumpy targets among smoother distractors, a colorXcolor conjunction search, and a search for any animal among other objects. Each participant was randomly assigned to one of five conditions: four fixed blocks of 100 trials, blocks whose order could be chosen, a random mixture of all four tasks, free choice of which task came next, and a ‘yoked’ condition where trials were presented in the order that someone else had chosen. Interestingly, when given the choice, participants rarely switched between tasks, choosing to run blocks of the same trials. Choice made no significant difference to the RTs across conditions, though, unsurprisingly, tasks differed in difficulty. Similarly, there were only very minor differences in errors between choice conditions. While task-switch imposes a cost in other situations, it does not appear to interfere with the performance of these visual search tasks.

Acknowledgements: NEI EY017001, NSF 2146617, NCI CA207490