Psychological Science 22(7) 872–877 © The Author(s) 2011 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/0956797611413293 http://pss.sagepub.com Most physical events generate signals that can be encoded in multiple sensory modalities, such as audition and vision. Because of the vast difference between the speeds of light and sound, visual and auditory signals are subject to distance- dependent changes in the relative times at which they reach people’s sensory receptors (see Alais & Carlile, 2005; Arnold, Johnston, & Nishida, 2005; King, 2005; Spence & Squire, 2003; Sugita & Suzuki, 2003). On the basis of their intensity, sensory signals are also subject to changes in the rates at which they propagate through the central nervous system (Burr & Corsale, 2001; Lennie, 1981). However, at least for proximate stimuli, humans are seldom aware of any asynchrony between an events’ multisensory components. One reason for this might be that the brain has some capacity to correct for extrinsically and intrinsically generated differences in sensory coding times. One plausible mechanism for this function is audiovi- sual temporal recalibration. Following prolonged exposure (adaptation) to streams of asynchronous auditory and visual events, timing perception can recalibrate, such that the timing of the adapted asynchronous signals seems more synchronous than it did previously (Di Luca, Machulla, & Ernst, 2009; Fujisaki, Shimojo, Kashino, & Nishida, 2004; Hanson, Heron, & Whitaker, 2008; Harrar & Harris, 2008; Heron, Whitaker, McGraw, & Horoshenkov, 2007; Keetels & Vroomen, 2007; Miyazaki, Yamamoto, Uchida, & Kitazawa, 2006; Navarra et al., 2005; Navarra, Hartcher-O’Brien, Piazza, & Spence, 2009; Vatakis, Navarra, Soto-Faraco, & Spence, 2007, 2008; Vroomen, Keetels, de Gelder, & Bertleson, 2004). This sub- jective recalibration of audiovisual synchrony is often accom- panied by increases in the range of timing differences across which auditory and visual signals seem synchronous (Hanson, Heron, & Whitaker, 2008; Navarra et al., 2005; Vatakis et al., 2007, 2008). Although recalibration of audiovisual timing perception could be beneficial, humans exist in a cluttered environment and can concurrently encounter many events that generate multisensory signals. Given that the signals generated by these events may be subject to different delays due to variable view- ing distances and signal intensities, it might not be beneficial Corresponding Author: Warrick Roseboom, University of Queensland, School of Psychology, McElwain Building, St. Lucia, Brisbane, Queensland 4072, Australia E-mail: w.roseboom@psy.uq.edu.au Twice Upon a Time: Multiple Concurrent Temporal Recalibrations of Audiovisual Speech Warrick Roseboom and Derek H. Arnold The University of Queensland Abstract Audiovisual timing perception can recalibrate following prolonged exposure to asynchronous auditory and visual inputs. It has been suggested that this might contribute to achieving perceptual synchrony for auditory and visual signals despite differences in physical and neural signal times for sight and sound. However, given that people can be concurrently exposed to multiple audiovisual stimuli with variable neural signal times, a mechanism that recalibrates all audiovisual timing percepts to a single timing relationship could be dysfunctional. In the experiments reported here, we showed that audiovisual temporal recalibration can be specific for particular audiovisual pairings. Participants were shown alternating movies of male and female actors containing positive and negative temporal asynchronies between the auditory and visual streams. We found that audiovisual synchrony estimates for each actor were shifted toward the preceding audiovisual timing relationship for that actor and that such temporal recalibrations occurred in positive and negative directions concurrently. Our results show that humans can form multiple concurrent estimates of appropriate timing for audiovisual synchrony. Keywords audiovisual simultaneity, audiovisual recalibration, subjective synchrony, audiovisual timing, temporal recalibration, audiovisual grouping, cross-modal grouping Received 9/28/10; Revision accepted 3/16/11 Research Report