Masked Priming with Graphemically Related Forms: Repetition or Partial Activation?

Form-priming occurs when a prime that is graphemically similar to the target word facilitates processing of the target. In an activation model (such as Morton’s logogen model), such an effect can be interpreted as a partial-activation effect. A prime that shares letters with the target must inevitably produce activation in the detectors for both the prime and the target. Alternatively, form-priming could be seen as a special case of repetition-priming, in which the prime actually accesses the entry for the target. It is shown that masked-priming effects in the lexical decision task can be obtained for graphemically related pairs such as bontrast–CONTRAST, but not for four-letter pairs such as bump–CAMP. It is suggested that the priming effect is controlled by neighbourhood density, short words usually having many neighbours, long words having very few. This hypothesis is supported by the finding that form–priming does occur for four–letter words if the prime and target are drawn from low–density neighbourhoods. For a partial–activation theory, an inhibitory mechanism that is sensitive to the number of prime–neighbours is required to explain the results. Of the several versions of a repetition account considered, the “best match” hypothesis appears to be the most promising: this assumes that priming is limited to the stimulus that best matches the prime. It is also shown that prime–target pairs that are related in form and meaning (e.g. made–MAKE) produce the same priming effect as identical pairs, as predicted by a repetition account that assumes a common entry underlying both forms.