When Word Identification Gets Tough, Retrospective Semantic Processing Comes to the Rescue

Semantic priming is typically enhanced by target degradation in both lexical decision and pronunciation tasks. Using these tasks, we examined this priming x target degradation interaction when the prime and target were related via symmetrical (SYM) associations (e.g., "east west"), as in previous research, or for the first time via forward asymmetrical (FA) prime-to-target associations (e.g., "keg beer") or backward asymmetrical (BA) target-to-prime associations (e.g., "small shrink") of the same strength as those in the SYM pairs. For both clear and degraded targets, SYM priming was equal to the sum of FA and BA priming, with BA priming being equivalent to FA priming except for clear targets in pronunciation, which as in previous research failed to yield significant overall BA priming. An analysis of the full reaction time (RT) distribution showed that (a) except for BA priming for clear targets in pronunciation, all priming effects were significant even for the fastest RTs, (b) priming effects were greater for degraded than clear targets for the BA and SYM pairs for the fastest RTs but more so for the longest RTs, and (c) priming effects were equal for degraded and clear targets for FA pairs throughout the RT distribution. For RT bins for which the RTs for degraded and clear unrelated targets were matched, RTs in the related priming condition were faster for degraded related targets than clear related targets. These findings suggest that the Priming x Target Degradation interaction typically observed for SYM related pairs is mediated by a retrospective prime-retrieval mechanism that depends on a backward target-to-prime association and is strategically engaged for degraded targets so that semantic information can compensate for the deficient bottom-up processing of a degraded target. They also provide strong evidence for the psychological reality of the general distinction between retrospective and prospective processing mechanisms, a distinction that has been receiving considerable recent interest in research on attentional control and memory. (Contains 7 tables and 1 figure.)