Psychophysical experiment on tactile stochastic resonance toward mathematical model

In the information processing done by biological organisms, stochastic resonance (SR) can enhance sensitivity by superimposing proper noise upon undetectable weak signals to detect that signal. In tactile sensing, since noise inevitably becomes mixed by contact with an object and a sensor´s movement on it, sensing accuracy can be increased by SR. In the present research, we perform a series of psychophysical experiments to accumulate the basic data on the SR of human tactile sensations. We developed an experimental apparatus composed of a piezoelectric actuator and a controller for it and generated a step several microns high mixed with noise. Since psychophysical experiments are conducted based on Parameter Estimation by Sequential Testing (PEST) method, we produce a computer program that generates stimuli sequence based on PEST. Experimental results show that a subtle stimulus of 3 μm in amplitude with appropriate noise is easily perceived with a difference threshold of about 1 μm if appropriate noise is applied to the stimulus.