The use of category information in perception.

Three tachistoscopic experiments are reported in which presentation of the target stimulus in a letter/digit categorization task was preceded by a briefly exposed priming stimulus (letter or digit). The primer was subject to backward masking from either the target or a pattern mask, and observers were unaware of its occurrence. With a primer duration of 25 ms, when masking was presumed to be at a central level, performance deteriorated when the two items were from different categories. This inhibition effect was reduced when the characters were physically similar. In contrast, there was little evidence of facilitated processing when primers validly cued targets. At shorter primer durations, when masking is presumed to be peripheral in origin, between-condition differences were less marked. An interpretation in terms of an active model of information processing, with utilization of both categorical and physical information extracted from the primer, is proposed.