Electronic Thesis and Dissertation Repository


Doctor of Philosophy




Lupker, Stephen J.


The present experiments were designed to investigate the locus of the semantic priming effect, a phenomenon that has received much research attention. Semantically related primes (e.g., cat) might activate the lexical representations of their targets (e.g., DOG) through automatic spreading activation at short stimulus onset asynchronies (SOAs) between the prime and target, or through generation of words expected to follow the prime at long SOAs. Alternately, semantically related primes might be used strategically to aid responding after target identification. The effects of masked orthographic primes (e.g., judpe-JUDGE), in contrast, are assumed to be strictly lexical and automatic. Lexical processing of targets is facilitated by orthographically similar masked nonword primes and is inhibited by orthographically similar masked word primes (Davis & Lupker, 2006). Using the lexical decision task (LDT), I found additivity between the facilitative effects of visible semantic primes at long and short SOAs and the facilitative effects of masked orthographically similar nonword primes and repetition primes. The masked nonword and repetition primes also produced a shift in the latency distribution of target responses, which is consistent with a head-start produced by pre-activating the target lexical representations. Semantic primes affected the skew of the distribution and had a greater effect on trials with longer latencies, consistent with the idea of those primes being used after target identification. Additionally, visible semantic primes at long and short SOAs did not make masked word primes more effective lexical inhibitors of their targets. Taken together, these findings suggest that the impact of a semantic prime is not to increase the lexical activation of its related target. Rather the locus of the semantic priming effect in an LDT appears to be a post-lexical process, consistent with the idea that the effect is due to the discovery of the existence of a relationship between the prime and target which biases participants to make a “word” response.