Poster #: 97
Wednesday, Sep 9, 2015
Higher-order auditory change detectors – support from behavioral and electrophysiological data
1Rotman Research Institute, Baycrest Centre, Toronto, Canada
Auditory changes are partly processed by dedicated change-detectors. Their activity can be indexed by the elicitation of the N1 and P2 event-related potentials (ERPs). Following this logic, distinct ERPs to first-order (i.e. constant-to-glide) frequency transitions provide evidence for first-order change detectors. However, evidence from ERP signatures for higher-order (i.e. glide-to-constant) transition detectors has remained sparse to date. This study aimed at elaborating the hypothesis that the asymmetry in ERP elicitation is not due to the complete lack of higher-order change detectors but due to their smaller number compared to first-order change detectors. To this end electrophysiological and behavioral data were collected to the corresponding transitions in different blocks in a go/ no-go paradigm. Each block utilized two types of sounds of equal probability which did or did not contain a transition (e.g. 50% constant-to-glide and 50% constant-only or 50% glide-to constant and 50% glide-only). The rate of frequency change within the glide was varied in different blocks (i.e. 10 vs 40 semitones per second) in order to increase the number of responding change detectors. Participants attended the sounds and were required to respond as fast as possible to the transition. The current data show distinct ERP signatures not only for first-order changes but, importantly, also for higher order changes when the frequency change rate of the glide was largest. This ERP result is accompanied by faster change detection on behavioral level. Thus, the current data support the proposed hypothesis and provide evidence for higher-order change detectors.