The influence of melodic and rhythmic redundancies on recognition memory for unknown musical themes.

The aim of this study was to assess the influence of melodic and rhythmic redundancies, and their interaction with tonality, on recognition memory for music. Forty-four non-musicians performed a recognition task with unknown musical material. Stimuli created for experimental purposes were made up of 48 short melodies (half tonal and half non-tonal) and were characterized by the presence of three kinds of musical redundancy: melodic only, rhythmic only, or both melodicrhythmic. In a first phase, subjects listened to a study list of 24 stimuli. After 20 minutes, a test list containing 48 stimuli (24 previously heard and 24 novel ones) was administered, and subjects were asked to indicate for each item whether the melody: was recognized from the study list (R response); evoked a sense of familiarity (K response); or was not recognized at all (X response). Major results showed that tonality influences semantic, but not episodic memory, and that the two systems are differentially affected by the type of redundancy (especially melodic-rhythmic, which has a large effect on episodic memory but is ineffective for semantic memory). Moreover, tonality and the type of redundancy systematically interact only in the episodic memory system. Thus, evidence supports disassociation of the two memory systems. Furthermore, R and X responses showed a symmetry in their trend, suggesting a role for X responses as counterparts of the R responses within the episodic memory system. Melodic-rhythmic redundancy demonstrated the most prominent effects on the episodic system, whereas the assessment comparing melodic versus rhythmic only as the pre-eminent type of redundancy was more ambiguous. Finally, non-tonal stimuli were found to be more sensitive than tonal stimuli, whereby they showed differential effectiveness regarding redundancy type, a result which suggests that they could prove serviceable in future studies concerning recognition memory for music.