Unity assumption between face and voice modulates audiovisual temporal recalibration

Audiovisual temporal recalibration refers to a shift in the point of subjective simultaneity (PSS) between audio and visual signals triggered by prolonged exposure to asynchronies between these signals. Previous research indicated that the spatial proximity of audiovisual signals can be a determinant of which pairs of signals are temporally recalibrated when multiple events compete for recalibration. Here we show that temporal recalibration is modulated by an observer’s assumption that the audiovisual signals originate from the same unitary event (“unity assumption”). Participants were shown alternating face photos and voices of the male and female speakers. These stimuli were presented equally spaced in time, and the voices were presented monaurally through headphones, such that no spatiotemporal-based grouping was implied for these stimuli. There were two conditions for the stimulus sequence in the adaptation phase: one in which a face photo always preceded its corresponding voice within each pairing of audiovisual stimuli (i.e., multiple repetitions of the sequence: female voice – male face – male voice – female voice), and the other one in which the corresponding voice always preceded its face photo. We found a shift in the PSS between these audiovisual signals towards the temporal order for the same gender person. The results show that the unity assumption between face photos and voices affects temporal recalibration, indicating the possibility that the brain selectively recalibrates the asynchronies of audiovisual signals that are considered to originate from the same unitary event in a cluttered environment.