The processing of structured and unstructured tonal sequences.

The recall of hierarchically organized tonal sequences was investigated in two experiments. An adaptation of the technique of melodic dictation was employed, in which musically trained listeners notated each sequence after it was presented. Strong effects of sequence structure were obtained. Sequences whose tonal structure could be parsimoniously encoded in hierarchical fashion were recalled with a high level of accuracy. Sequences that could not be parsimoniously encoded produced substantially more errors in recall. Temporal segmentation was found to have a substantial effect on performance, which reflected grouping by temporal proximity regardless of tonal structure. The results provide evidence for the hypothesis that we encode tonal materials by inferring sequence structures and alphabets at different hierarchical levels, together with their rules of combination.