Suffix interference in the recall of linguistically coherent speech

Four experiments are presented that address the stimulus suffix effect for linguistically coherent spoken materials. In Experiment 1, definitions of low-frequency words were presented for online written recall. Each definition was followed by a nonword speech suffix presented in the same voice as the definition, the same nonword presented in a different voice, or a tone. The results yielded a significant reduction in the recall of the terminal words of the definitions in the speech suffix conditions compared with the tone control. This general pattern was replicated in Experiment 2, in which subjects did not begin their recall until the suffix item or tone was presented, although the magnitude of the suffix effect was reduced in this experiment. In Experiment 3, sentences that were part of a cohesive story were presented for on-line recall. Here, the suffix effect was considerably reduced compared with the suffix effect found with the definitions presented in Experiments 1 and 2. This pattern was replicated in Experiment 4, in which subjects did not begin their recall of the story sentences until the speech suffix or tone was presented. Overall, the results suggest that auditory memory interference can take place for linguistically coherent speech, although the magnitude of the interference decreases as one increases the level of linguistic structure in the to-be-recalled materials. Implications of the present results for current models of natural language processing are discussed.