Training tactile sensing for shape recognition is considered to be an effective rehabilitation technique. Previous studies in tactile sensing showed a tendency of recognition ambiguity, thus necessitating tactile sensing rehabilitation. Eleven subjects observed invisible objects using their fingers and were asked to identify the shape of the objects. The relationship between the degree of recognition and shape complexity was investigated. The results showed high self-confidence in recognizing high complexity shapes. The recognition process was confirmed in a second experiment measuring brain activation using near-infrared spectroscopy. Measurement of eight subjects showed the activation of verbal and visual processing regions, indicating that the act of handling the shape was translated to verbal expression and visual imaging. These results potentially quantify tactile sensing and contribute to the realization of personalized rehabilitation.

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