When three stimulators are simultaneously touched with the middle three fingers of one hand but only the outer two stimulators are cooled or heated, the central (neutral) stimulator is also perceived to be cold or warm. This phenomenon is known as thermal referral and it shares phenomenological similarities with filling-in, in which the discontinuity in the signals of interest can be compensated perceptually on the basis of the spatially adjacent context. Although the mechanisms underlying filling-in have been well substantiated, those underlying thermal referral are still poorly understood. In the present study, we examined the intensity perception of the sensation resulting from thermal referral with human participants. We found that the sensation was uniform among the three fingers, but its apparent intensity was always lower than the physical intensity applied to the outer two fingers. These results indicate that the thermal uniformity perceived under thermal referral is not created by the brain's interpolating the thermal changes applied to the outer two fingers, as one would expect for those induced by typical filling-in. Instead, the thermal changes applied to the outer two fingers are summated and redistributed to all the fingers in contact. Our findings suggest that thermal referral is mediated by two separate processes. One determines the apparent intensity from the physical intensity and the areal extent of the thermal stimulation; the other determines the localization of the resulting sensation from the apparent sites of tactile stimulation.

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When a small mass in a hand-held device oscillates along a single axis with asymmetric acceleration (strongly peaked in one direction and diffuse in the other), the holder typically experiences a kinesthetic illusion characterized by the sensation of being continuously pushed or pulled by the device. This effect was investigated because of its potential application to a hand-held, nongrounded, haptic device that can convey a sense of a continuous translational force in one direction, which is a key missing piece in haptic research. A 1 degree-of-freedom (DOF) haptic device based on a crank-slider mechanism was constructed. The device converts the constant rotation of an electric motor into the constrained movement of a small mass with asymmetric acceleration. The frequency that maximizes the perceived movement offered by the haptic device was investigated. Tests using three subjects showed that for the prototype, the best frequencies were 5 and 10 cycles per second.

This paper proposes the concept of Parasitic Humanoid (PH) that can realize a wearable robot to establish intuitive interactions with wearers rather than conventional counter-intuitive ways like key-typing. It requires a different paradigm or interface technology which is called behavioral or ambient interface that can harmonize human-environment interactions to naturally lead to a more suitable state with the integration of information science and biologically inspired technology. We re-examine the use of wearable computers or devices from the viewpoint of behavioral information. Then, a possible way to realize PH is shown as integrated wearable interface devices. In order that PH establishes the harmonic interaction with wearers, a mutually anticipated interaction between a computer and human is necessary. To establish the harmonic interaction, we investigate the social interaction by experiments of human interactions where inputs and outputs of subjects are restricted in a low dimension at the behavioral level. The results of experiments are discussed with the attractor superimposition. Finally, we will discuss integrated PH system for human supports.

Galvanic vestibular stimulation (GVS) can be applied to induce the feeling of directional virtual head motion by stimulating the vestibular organs electrically. Conventional studies used a two-pole GVS, in which electrodes are placed behind each ear, or a three-pole GVS, in which an additional electrode is placed on the forehead. These stimulation methods can be used to induce virtual head roll and pitch motions when a subject is looking upright. Here, we proved our hypothesis that there are current paths between the forehead and mastoids in the head and show that our invented GVS system using four electrodes succeeded in inducing directional virtual head motion around three perpendicular axes containing yaw rotation by applying different current patterns. Our novel method produced subjective virtual head yaw motions and evoked yaw rotational body sway in participants. These results support the existence of three isolated current paths located between the mastoids, and between the left and right mastoids and the forehead. Our findings show that by using these current paths, the generation of an additional virtual head yaw motion is possible.