Dimensionality of thermal icons

The thermal sensory modality provides a novel dimension to present information to users of a variety of hand-held devices provided the inputs are tailored to the properties of the sensory system. The objective of the present experiment was to measure thermal pattern identification on the thenar eminence at the base of the thumb using a set of six stimuli that varied with respect to the direction, magnitude and rate of temperature change. An absolute identification paradigm was used in which each stimulus was presented eight times and participants had to identify which stimulus was presented using a visual template that depicted the thermal icon. The individual mean scores averaged across all stimuli ranged from 80% to 98% correct with an overall mean of 91%, indicating that the thermal icons were relatively easy to identify. The Information Transfer values ranged from 1.76 to 2.49 bits across participants with a group mean of 2.26 bits. These findings indicate that thermal icons offer considerable potential for presenting information as part of a haptic interface, and that the information transfer capabilities of the thermal sense may rival those achieved with vibrotactile inputs, although at the cost of a prolonged presentation time.