Abstract
Characteristic sounds (without location information) facilitate target localization in visual search (VSS 2007). For example, when the target is a cat, a simultaneously presented “meow” sound speeds localization of the cat compared to other sounds and no sounds. Previously, the target was always present and different on each trial (indicated at the trial beginning). We tested whether this object-specific auditory-visual facilitation might benefit target detection in a vigilance paradigm when targets are rare and always of a specific category. Participants looked for different exemplars from a single category (guns or cats), pressing one button to indicate target presence and another button to indicate target absence. Targets were rare (10%). Each participant was tested in three blocks totaling 450 trials. In the target-consistent-sound block, participants heard sounds characteristic of the target category on every trial (different “meow” sounds if cats were the target category, and different gun sounds if guns were the target category). In the control condition, participants heard sounds characteristic of the other category on every trial (different gun sounds if cats were the target category, and different “meow” sounds if guns were the target category). In the third condition, participants heard no sounds (with the block order counterbalanced across participants). Target detection and distractor rejection were both significantly faster when target-consistent sounds were presented on every trial compared to when irrelevant sounds or no sounds were presented (with no evidence of a speed-accuracy trade-off), indicating that characteristic sounds increased target discriminability rather than simply biasing target responses. Thus, when people repeatedly search for rare targets of a specific category, presenting sounds characteristic of the target category on every trial facilitates target detection. If this auditory-visual facilitation persists for a longer time scale (hours), the technique could be applied to rare-target searches in real-life situations as in baggage screening.
NIH grant EY14110 and NSF grant BCS0643191.