Invariance of long-term visual priming to scale, reflection, translation, and hemisphere

The representation of shape mediating visual object priming was investigate d. In two blocks of trials, subjects named images of common objects present ed for 185 ms that were bandpass filtered, either at high (10 cpd) or at lo w (2 cpd) center frequency with a 1.5 octave bandwidth, and positioned eith er 5 degrees right or left of fixation. The second presentation of an image of a given object type could be filtered at the same or different band, be shown at the same or translated (and mirror reflected) position, and be th e same exemplar as that in the first block or a same-name different-shaped exemplar (e.g. a different kind of chair). Second block reaction times (RTs ) and error rates were markedly lower than they were on the first block, wh ich, in the context of prior results, was indicative of strong priming. A c hange of exemplar in the second block resulted in a significant cost in RTs and error rates, indicating that a portion of the priming was visual and n ot just verbal or basic-level conceptual. However, a change in the spatial frequency (SF) content of the image had no effect on priming despite the dr amatic difference it made in appearance of the objects. This invariance to SF changes was also preserved with centrally presented images in a second e xperiment. Priming was also invariant to a change in left-right position (a nd mirror orientation) of the image. The invariance over translation of suc h a large magnitude suggests that the locus of the representation mediating the priming is beyond an area that would be homologous to posterior TEO in the monkey. We conclude that this representation is insensitive to low lev el image variations (e.g. SF, precise position or orientation of features) that do not alter the basic part-structure of the object. Finally, recognit ion performance was unaffected by whether low or high bandpassed images wer e presented either in the left or right visual field, giving no support to the hypothesis of hemispheric differences in processing low and high spatia l frequencies. (C) 2001 Elsevier Science Ltd. All rights reserved.