Neural processing of voices - familiarity

Abstract

Brain responses to familiar and unfamiliar voices were investigated with ERPs (Event Related Potentials). Presentation of a stream of one syllable utterances from a female voice established a standard expectation, and similar samples from four other male voices where inserted as unexpected deviants in a typical mismatch paradigm. The participants were 12 students from the basic course in linguistics. Two of the deviant voices were familiar voices of their teachers. The two other deviant voices were matched (same age, sex and dialect) but unfamiliar to the participants. A typical MMN (Mismatch Negativity) was elicited, i.e. a more negative response to the deviants compared to the standards. In contrast to verbal reports, where only one participant identified any of the deviant voices, the MMN response differed on group level between familiar and unfamiliar voices. MMN to familiar voices was larger. Using teachers' voices ensured naturalistic long term exposure, but did not allow for random assignment to conditions of familiarity making the design quasi-experimental. Thus acoustic analysis of voice characteristics as well as follow up studies with randomized exposure to voices are needed to rule out possible confounds and establish a causal effect of voice familiarity.