The role of skin coupling in the determination of vibrotactile spatial summation

The method of magnitude estimation was used to determine the psychophysical functions for three forms of subjective automobile speed. Observers experienced linear motion across the visual field, the approach motion of an oncoming car, and “en route” motion as a passenger. All three conditions resulted in power function relations between subjective speed and physical velocity. The respective exponents were 1.0, 1.35, and 1.40. Direct category estimates of en route speed were related linearly to physical velocity, but nonlinearly to subjective speed.