The effect of orthographic structure and lexical meaning on “same-different” judgments

Pairs of high frequency English words, orthographically acceptable pseudo-words, and non-word letter strings were presented in a “same”-“different” task. The mean reaction times for “same” judgments were ordered; real words were faster than pseudo-words, and pseudo-words were faster than non-words. The RTs for the “different”, judgments showed no differences among the three types of words, except in the first two days of practice in a blocked presentation condition when the difference between the real words and non-words was marginally significant. These and other results suggest that “same” judgments are based upon a comparison process which efficiently uses higher order semantic and orthographic information in words, whereas “different” judgments are based upon comparison process which performs a self-terminating search of the graphemic information in words. The results were also discussed with reference to hierarchical models of word perception and reading.