Semantic processing of highly repeated concepts presented in single-word trials: Electrophysiological and behavioral correlates.

Repetition has often been associated with a reduction or a suppression of semantic effects. However, several studies have reported that semantic processing can still be effective for repeated target stimuli when the context, prime word or sentence frame, changes from trial to trial. This type of context-target designs allows to study semantic associations between repeated words. However, it is not optimal to study single concepts or categories and therefore structural aspects of semantic memory. Here, we tested whether semantic effects could be observed if single-word trials were used. Concrete and Abstract words were presented multiple times in two concrete-abstract classification experiments. In the first experiment, 6 words of each category were repeatedly presented. In the second experiment, only one word of each category was used. Results of both experiments showed significant effects of concreteness on reaction times and N400-like event-related potentials (ERPs), which were comparable to those reported in non-repeated conditions. In the second experiment, in which repetitions occurring in consecutive and non-consecutive trials were contrasted, N400-like effects were observed only for non-consecutive repetitions. These findings suggest that it could be possible to study the brain activity corresponding to individual concepts in experimental designs using single-word trials, provided that consecutive repetitions are avoided.