Auditory-tactile temporal order judgments during active exploration
Ilja Frissen, Mounia Ziat, Gianni Campion, Vincent Hayward, Catherine Guastavino
Time: 2009-07-01 09:00 AM – 10:30 AM
Last modified: 2009-06-04
We investigated if motor activity affects cross-modal perceptual temporal alignment. Fifteen participants were presented with an auditory-tactile stimulus pair and made temporal order judgments as to which one of the two came first. For the tactile stimulus we employed a high fidelity haptic device called the Pantograph; it generates forces at a moveable plate that cause tactile sensations at the fingertip that resemble exploring surfaces. It was possible to present a stimulus where the finger was stationary (Static condition), where the participant was motorically passive but was moved about by the actuators of the device (Passive), or where the participant moved actively (Active). The tactile stimulus was a brief supra-threshold force pulse orthogonal to the hand movement. The auditory stimulus was a short tone heard over headphones. The points of subjective simultaneity (with positive values indicating the auditory stimulus had to be presented before the tactile one to be perceived as simultaneous), were 9 ms (Static), -29 ms (Passive), and 12 ms (Active). One compelling interpretation of these results is that hand movements do cause a shift in temporal alignment (Passive re: Static) but efference copies from active motor commands are used to compensate (Active re: Static) for this shift.