A critical experimental study of the classical tactile threshold theory

Area of Science:

• Psychophysics
• Human-Computer Interaction
• Sensory Neuroscience

Background:

• The classical threshold concept is widely used to model tactile perception and phenomena like stochastic resonance (SR).
• SR explains that noise can enhance the detection of sub-threshold stimuli by helping them cross a sensory threshold.
• The validity of the classical vibrotactile threshold in human-machine interfaces requires further investigation.

Purpose of the Study:

• To experimentally test the validity of the classical vibrotactile threshold.
• To investigate if sensory events below the classical threshold can be perceived and ordered by individuals.

Main Methods:

• A three-alternative forced choice detection experiment was conducted with 6 subjects.
• Subjects were asked for first and second choices in trials containing one stimulus and noise.
• The experiment specifically assessed the ability to identify stimuli below the classical threshold level.

Main Results:

• Experimental results showed an average of 67.35% (STD = 1.41%) for correct second choice responses, significantly above the 50% chance level.
• This finding contradicts the classical threshold definition, as it implies perception of stimuli below the assumed threshold.
• Second choice correct detection remained above chance level for low stimulus amplitudes across all detectability levels.

Conclusions:

• Individuals can order sensory events below the classical tactile threshold.
• The classical threshold model is insufficient for explaining phenomena like SR and other tactile perceptions.
• A revised or alternative model is necessary to accurately represent the tactile sensory system's capabilities.