Alternative spatial reference systems: Intentional vs. incidental learning

Subjects were initially shown unfamiliar polygons while their heads were tilted and were then tested for their ability to recognize the polygons when their heads were upright. The objective (gravitational) orientation of the polygons during acquisition affected recognition accuracy only when the polygons were acquired under intentional learning instructions. When acquisition was incidental, evidence for the retention of retinally referenced memory representations was obtained. These results were consistent with a review of previous literature indicating that the use of a task requiring either the storage or retrieval of information from memory is a necessary (although not sufficient) condition for obtaining an effect of objective orientation on performance.