The Case of the Missing Visual Details: Occlusion and Long-Term Visual Memory

To investigate the critical information in long-term visual memory representations of objects, we used occlusion to emphasize one type of information or another. By occluding one solid side of the object (e.g., top 50%) or by occluding 50% of the object with stripes (like a picket fence), we emphasized visible information about the object, processing the visible details in the former and the object's overall form in the latter. On a token discrimination test, surprisingly, memory for solid or stripe occluded objects at either encoding (Experiment 1) or test (Experiment 2) was the same. In contrast, when occluded objects matched at encoding and test (Experiment 3) or when the occlusion shifted, revealing the entire object piecemeal (Experiment 4), memory was better for solid compared to stripe occluded objects, indicating that objects are represented differently in long-term visual memory. Critically, we also found that when the task emphasized remembering exactly what was shown, memory performance in the more detailed solid occlusion condition exceeded that in the stripe condition (Experiment 5). However, when the task emphasized the whole object form, memory was better in the stripe condition (Experiment 6) than in the solid condition. We argue that long-term visual memory can represent objects flexibly, and task demands can interact with visual information, allowing the viewer to cope with changing real-world visual environments. © 2017, American Psychological Association. This paper is not the copy of record and may not exactly replicate the final, authoritative version of the article. Please do not copy or cite without authors permission. The final article will be available, upon publication, via its DOI:10.1037/xlm0000393

Portions of the data were reported at the 56th annual meeting of the Psychonomic Society, Chicago, IL, November 2015 and the 57th annual meeting of the Psychonomic Society, Boston, MA, November 2016. We thank Alisha Kent, Conner Maloney, Angie Rodriguez, Danielle Struwe, and Anahi Guerrero for their assistance in data collection. Correspondence concerning this article should be addressed to Carrick Williams, Department of Psychology, 333 S Twin Oaks Valley Rd, San Marcos, CA 92096. Email:  cawilliams@csusm.edu.