2 experiments were conducted in which Ss gave 1 of 3 responses to each stimulus in a random sequence prepared from 32 distinct stimuli which assumed 1 of 2 levels for each of 5 dimensions. The sequence was constructed so that 2 of the 32 stimuli occurred with probability 1/3 each and the remaining 30 stimuli occurred with probabilities summing to 1/3. Ss were instructed to respond by depressing a - key to 1 of the high frequency stimuli, a + key to the other, and a 0 key to any of the remaining 30. Results support the hypothesis that frequently occurring stimuli may be identified as total patterns, perhaps by some sort of template matching which compares all dimensions simultaneously. However, the results also suggest that the template matches are made serially, and infrequent (or unfamiliar) stimuli are identified by a serial examination of stimulus dimensions. (PsycINFO Database Record (c) 2006 APA, all rights reserved)