Stimulus Distribution Shapes Color and Vibrotactile Perception.

Perception is shaped by both the physical properties of stimuli and their contextual presentation, often leading to systematic biases such as the central tendency effect, where perceptual judgments shift toward the average of the stimulus set. This study explored the central tendency bias in vibrotactile perception, an area that has received limited attention while also replicating its well-documented occurrence in color perception to validate previous findings. Using a within-subject design, participants (5 males, 15 females) completed color and vibrotactile discrimination tasks, each consisting of three blocks, which comprised systematically shifted stimulus sets. In an established virtual reality color task, stimuli ranged from yellow-green to blue-green, while in the vibrotactile task, stimuli varied in vibration intensity around a baseline distribution. As predicted, the point of subjective equality shifted toward the mean of the stimulus sets in both tasks, confirming the presence of a central tendency bias. These findings demonstrate that perception of both color and vibrotactile intensity is not determined solely based on the physical properties of the stimulus per se, but it is rather influenced by the distribution of the presented stimuli, underscoring the pervasive role of contextual factors in shaping sensory judgments.