Global-local temporal auditory processing: reorganization with musical training and interindividual differences
Résumé
Recent works suggest that the global-local organizational principles of auditory processing are comparable to that of visual processing, with a superior efficiency as well as stronger interferences of global over local processing. Yet, the factors governing auditory local-global processing organization remain poorly understood. Here, we introduce a novel paradigm that attempts to better characterize local-global temporal processing taking into account musical expertise. The ability of non-musicians as well as expert musicians to detect local and/or global pitch changes occurring in short hierarchical sequences is assessed. Importantly, melodic structures of different complexity are considered, in which the changes can occur at various temporal positions and over different scales, thus forcing listeners to attend to the whole sequences. Built in a signal detection theory framework, this experimental paradigm provides ideal conditions to assess potential global-local interference effects and tease apart differences in processing efficiencies vs. response strategies. On average, our results demonstrate a clear distinction between the local-global processing organization of non-musicians and musicians. While non-musicians show clear global advantage and global-to-local interference ef- fects, in line with previous observations, this pattern is reversed in musicians. Yet, we observe important interindividual differences within each group, with some non-musicians exhibiting a global-local organization similar to that of expert listeners. Overall, these results provide a detailed characterization of how the different temporal processing scales are re-organized following long-term musical training, with a reversal of the initial global predominance to provide mu- sicians with enhanced analytic listening abilities. More interestingly, they suggest that this reorganization is mediated by both increased general auditory abilities as well as the acquisition of novel discrimination strategies. Overall, the present study yields new insights regarding the organization of our perceptual system to deal with auditory information over different temporal scales, and shows how this can be reshaped through experience and training.