Visual comparison of words and random letter strings: Effects of number and position of letters different.

Ss classified tetragrams as either "same" or "differen". Stimuli were either words or consonant strings. In the case of different pairs, the number and position of letters different were controlled. Words were compared faster than random strings under all conditions. Consistent effects of the number and position of letters different suggest that word superiority is not due to phonemic recoding. For both words and consonant strings "same" RT to a given pair was faster when it was from a block in which "different" pairs had three rather than one letter different. This suggests that the wholistic identity reporter involves a criterion process sensitive to the magnitude of expected differences. Different RTs were faster in all conditions for three-letter different pairs rather than one-letter different pairs, ruling out a fixed order self-terminating search process for "different" decisions.