Size invariance in visual object priming.

The magnitude of priming resulting from perception of a briefly presented picture of an object in an earlier trial block, as assessed by naming reaction times (RTs), was independent of whether the primed object was presented at the or a different size as when originally viewed. RTs and error rates for same responses for old-new shape judgments were much increased by a change in object size from initial presentation. We conjecture that this dissociation between the effects of size consistency on naming and old-new shape may reflect the differential functioning of 2 independent systems subserving object memory: 1 for representing object shape and the other for representing its size, position, and orientation (metric attributes). Allowing for response selection, object naming RTs may provide a relatively pure measure of the functioning of the shape system. Both the shape and metric systems may affect the feelings of familiarity that govern old-new episodic shape judgments. A comparison of speeded naming and episodic judgments may provide a behavioral, noninvasive technique for determining the neural loci of these 2 systems. The recognition latency of a shape originally viewed at one size is lengthened when that shape is presented at a different size (Jolicoeur, 1987). This result, and a number of others demonstrating time costs for comparing two simultaneously (or immediately sequential) presented shapes that differ in size (Besner, 1983; Bundesen Ellis, Allport, Humphreys, Jolicoeur Larsen, 1985; Larsen Ullman, 1989).' To achieve matching of the representation of that shape when it is presented at a different size, according to this view, scaling transformations are necessary (e.g., Ullman, 1989). Presumably, the additional time to perform these transformations is the reason why the match of a different-size shape requires more time. Recognition was placed in quotes in the previous paragraph because, curiously, the effects of size consistency on a relatively direct measure of object classification, basic-level naming, have never been assessed. Jolicoeur's (1987) measure of was old-new discrimination. Jolicoeur himself cautioned that it was possible that the effects of size inconsistency in his experiment were not reflecting the perceptual representation used for pattern of the object but rather the processes for episodic discrimination. We report here that Jolicoeur's disquiet was well founded: Size consistency does not affect basic-level naming reaction times (RTs). We used a picture-primin g task where it has been well documented that an object viewed on one occasion