Attempted to replicate the essential features of L. Crespi's (see record) study as it relates frustration to positive contrast, using 40 male Sprague-Dawley rats. Experimental Ss were shifted from large to small incentive before being shifted back to large incentive to test for positive contrast. The 2nd shift was made when Ss were running slowly, on the assumption that this reflected frustration from the 1st shift. Comparison with controls showed a significant positive contrast under 2 drive levels. (PsycINFO Database Record (c) 2006 APA, all rights reserved)