Poster #: 66
Topic: Memory and perception
Friday, Sep 11, 2015
Shifting pitch: time course of extracting regularities from unfamiliar complex sound patterns
1Cognitive and Biological Psychology, University of Leipzig, Leipzig, Germany
2Institute of Psychology, University of Leipzig, Leipzig, Germany
We are able to implicitly learn abstract auditory regularities, e.g. regularities based on the relations between sound features, such as a melody played in different keys. The aim of the current study was to uncover the impact of such a “relative pitch code” on pattern regularity extraction in a roving paradigm. Presented sound patterns consisted each of six consecutive 50-ms segments of randomly chosen pitch. In order to compare the build-up of regularity representations, we introduced an absolute repetition condition, in which patterns were identically repeated (1-12 times), and a transposed condition, in which only the pitch relations of patterns were repeated, whereas the entire patterns were shifted up or down in pitch. During an EEG session, participants paid attention to the loudness of the stimuli, but not to the roving rule. A following active behavioral detection task ensured the behavioral detectability of pattern changes.
Results indicate that pattern learning occurs rapidly as deviance-related components were present after only 2-3 pattern presentations. Markers of regularity encoding (repetition positivity) point to early differences in pattern regularity extraction, i.e. stronger matching in the absolute repetition condition. Nevertheless, at the stage of MMN, pattern change detection was comparable in strength and time course for both conditions. The P3a, however, differed markedly in latency and amplitude between conditions mirroring massive impairments in the active pattern change detection task in the transposed condition. Consequently, the impact of relative vs. absolute pitch regularities differs as a function of the processing stage.