| Research in both stimulus-response compatibility and negative priming seeks to understand the control mechanisms involved in response-selection processes. Stimulus-response compatibility refers to the finding that reaction times are faster when the stimuli and responses correspond than when they do not. In a typical negative priming task, two successive trials are examined. Negative priming refers to the finding that reaction times are longer when the current (probe) trial's target served as an irrelevant distractor stimulus on the previous (prime) trial, compared to a neutral trial for which the probe target is unrelated to prime trial events. This longer reaction time is believed to be a direct measure of inhibitory effects from the prime trial.;Shiu and Kornblum (1996) demonstrated negative priming without distractors in an incongruent symbolic task with verbal responses, in which they alternated pictures with words. Reaction times were longer when the stimulus identity (incorrect corresponding response) on the prime trial became the probe target response. Shiu and Kornblum intrepreted this "negative priming" effect as reflecting inhibition of the corresponding (automatic) response from the prime trial. Read and Proctor (2004) replicated Shiu and Kornblum's finding using an analogous spatial task with keypress responses. However, when the mapping was changed, such that subjects could adopt a simple transformational rule, positive priming occurred.;Six experiments are reported that extend Read and Proctor's research by examining the conditions under which negative priming occurs in comparable spatial and symbolic tasks. Experiments 1 and 2 were similar to Read and Proctor's Experiments 1 and 2, but used word stimuli and verbal responses instead of spatial locations and keypress responses. The results were similar to those with the spatial tasks. Experiments 3 through 6 explored inhibition and facilitation for these symbolic and spatial tasks in a variation of the negative priming task. Based on past research, facilitation and inhibition were inferred through the temporal dynamics of different trial types. Results support a residual inhibition account, as proposed by Shiu and Kornblum for negative priming effects. However, the results also suggest that inhibition of the corresponding response depends on subjective expectancy, task complexity, and task goals. |
