Additive and interactive effects in semantic priming: Isolating lexical and decision processes in the lexical decision task.

The present study sheds light on the interplay between lexical and decision processes in the lexical decision task by exploring the effects of lexical decision difficulty on semantic priming effects. In 2 experiments, we increased lexical decision difficulty by either using transposed letter wordlike nonword distracters (e.g., JUGDE; Experiment 1) or by visually degrading targets (Experiment 2). Although target latencies were considerably slowed by both difficulty manipulations, stimulus quality-but not nonword type-moderated priming effects, consistent with recent work by Lupker and Pexman (2010). To characterize these results in a more fine-grained manner, data were also analyzed at the level of response time (RT) distributions, using a combination of ex-Gaussian, quantile, and diffusion model analyses. The results indicate that for clear targets, priming was reflected by distributional shifting of comparable magnitude across different nonword types. In contrast, priming of degraded targets was reflected by shifting and an increase in the tail of the distribution. We discuss how these findings, along with others, can be accommodated by an embellished multistage activation model that incorporates retrospective prime retrieval and decision-based mechanisms.