Implicit learning of base rate information in change detection occurs for location but not identity

Abstract

Previous research using visual search tasks and target localization tasks demonstrates that the visual system can implicitly learn base rate information and then use this information to guide visual attention. Recent findings showing that changes with a high base rate are detected more readily than low base rate changes suggests that this ability may apply to change detection tasks as well. We examined the possibility that change probabilities can be implicitly learned while completing a change detection task and then used to improve change detection performance. Participants completed 120 training trials during which one of six shapes changed color. In the shape condition, the shape that changed color was the same identity on every trial. In the location condition, the shape that changed color was always in the same location. Ability to learn and use this change regularity information was examined with 24 test trials in which changes occurred in the trained location or shape on 12 trials and the untrained locations or shapes for the remaining 12 trials. In the shape condition, change detection performance for the trained shape was not different from performance on the untrained shapes. In the location condition, change detection performance was better for the trained location than the untrained locations. Post-experiment questionnaires revealed that participants did not have explicit knowledge of the trained change probability for the shape or the location conditions. These results indicate that implicit acquisition of change probability information occurs for location but not identity.