Contrast and illumination effects on explicit and implicit measures of memory.

Abstract

The present study examined the effect of changing the contrast polarity and illumination of objects on explicit (episodic recognition) and implicit (fragment naming or object-nonobject decision) memory tasks. Changes in contrast polarity of line drawings of objects did not affect priming on fragment naming or on object-nonobject decision tasks but adversely affected recognition judgments. Similarly, changes in illumination did not affect priming on the object-nonobject decision task but adversely affected recognition memory. Together, the results suggest that implicit measures tap abstract descriptions of object structure useful for the purposes of object identification, whereas recognition memory taps descriptions that integrate shape information with lower level perceptual information. It is argued that lower level perceptual information influences episodic recognition because it provides a cue to the spatiotemporal context within which the prior encounter with the object occurred.