Detecting anomalous features in complex stimuli: the role of structured comparison.

The ability to detect anomalies in perceived stimuli is critical to a broad range of cognitive tasks, yet acquiring this ability often requires lengthy practice. In this research, we asked whether findings from research on analogical comparison can be used to aid in the acquisition of perceptual expertise. Building on findings that comparison can facilitate the detection of differences, the present research addressed two questions: (1) Does having an alignable comparison standard improve performance on a difficult detection task? (2) Can such comparison experience improve subsequent detection performance on single anomalous targets? Across 3 experiments, university undergraduates were asked to find an anomalous bone in drawings of animal skeletons. Target items including an anomaly were presented either alone or with a correct standard. Furthermore, to evaluate the impact of ease of alignment, the correct standard was presented either mirror-reversed (low alignable) or regular (high alignable). Results showed increased accuracy when a comparison standard was present and further gains when the standard was more easily alignable. In Experiment 3, we used a between-subjects design to reveal that advance comparison (as opposed to single-item training) led to improved detection of anomalies in subsequent novel examples presented as isolated targets. We conclude that the availability of a standard and ease of alignment promote encoding and processing. Furthermore, comparison-based learning confers an ongoing advantage even without standards for comparison. Therefore, task performance in application areas requiring detection of nonobvious anomalies can be improved by providing alignable standards next to targets or in advance training.