Performance in a within-modality temporal order judgment task reveals suboptimal multisensory integration following stimuli presentation at peak limb velocity


Auditory and visual cues can be integrated in a statistically optimal fashion (e.g., Ernst & Bülthoff, 2004). However, the weighting of auditory and visual information for multisensory integration appears to change as a function of limb velocity (Tremblay & Nguyen, 2010; Loria, de Grosbois & Tremblay, submitted). The current study was designed to assess whether audiovisual information is optimally integrated at peak limb velocity. Participants (N = 13) were required to "fling" their limb through the centre of a virtual target (i.e., right index finger to reach peak velocity as it intersected the target). Piezo-LED devices were affixed on both sides of the virtual target and provided two auditory, visual, or audiovisual cues when the participant reached their peak limb velocity, or while the participant remained stationary. After each trial, participants completed a within-modality temporal order judgment task (TOJ), reporting which side of the virtual target the first sensory cue was presented. When analyzing response accuracy at rest, it was found that participants were more accurate in judging the order of the events (i.e., TOJ) in the auditory and audiovisual condition relative to the visual condition. Also, performance in the audiovisual condition was significantly less accurate when the sensory cues were presented at peak limb velocity compared to at rest. Overall, the results from this experiment in conjunction with those reported previously (e.g., Loria et al., submitted; Tremblay & Nguyen, 2010) suggest that the central nervous system integrates sensory information in a manner that may not always be optimal.

Acknowledgments: Natural Sciences and Engineering Research Council, Ontario Research Fund, Canada Foundation For Innovation