Collaborative search in a mock baggage screening task.

Signal detection theory provides models of information integration that allow researchers to predict and benchmark collaborative performance in a visual search task. Naturalistic stimuli, however, may not conform to the simplifying assumptions-specifically, assumptions of equal-variance signal and noise distributions and stochastically independent observers-that are often made to make collaborative signal detection models tractable. Here, we used Bayesian hierarchical modeling of receiver operating characteristics to circumvent this difficulty. Participants ( = 28-32 per experiment) performed a simulated baggage x-ray screening task, working alone or in teams of 2. Team performance was compared with the predictions of 2 versions of a uniform weighting model of information integration, 1 that assumed stochastically independent judgments from the 2 members of a team and 1 that allowed for correlated judgments. Across 4 experiments, teams fell short of the uncorrelated-judgment model's predictions, but outperformed predictions based on the observed correlations in individual judgments. Results imply motivational effects that improve individual searchers' effort under collaborative conditions, or collaborative strategies that effectively decorrelate the individual searchers' judgments. (PsycINFO Database Record (c) 2019 APA, all rights reserved).