Object orientation information in semantic and episodic memory

The time required to identify a common object depends on several factors, especially pre-existing knowledge in semantic memory, and episodic representations newly established as a result of a prior,study. We report three experiments that investigated the relative contribution of these factors to implicit and explicit memory test performance. In each experiment, subjects were shown color photos of objects and memory was assessed either with an old/new recognition test or with a test that required them to identify objects that were slowly faded in on a computer monitor. The critical variables were the type of photo - each showing either an object with a predominant or cardinal orientation (e.g., helicopter) or a non-cardinal object (e.g., pencil), and the orientation at which the photos-were displayed at study and at test (e.g., on the plane of the page at 0 degrees, 120 degrees, 180 degrees, 240 degrees). For each subject, half of the targets were shown at study and all appeared on the test, with targets displayed either in the same orientation as at study or in a different orientation. For non-studied targets (i.e., in the baseline condition), identification test performance showed a huge effect due to display orientation, but only for cardinal objects. For studied targets, identification test performance showed substantial priming in all conditions, with more priming on cardinal than non-cardinal targets, especially when their display orientation at test was unusual (i.e., 120 degrees, 240 degrees) and the same as at study. We use these findings to discuss the extent to which orientation information is coded in the semantic and episodic memory representations of different kinds of objects.