![]() ![]() The Bayesian model reaches an optimal probabilistic inference by combining uncertain spatial sensory information with a prior expectation for low-speed movement (a Gaussian prior distribution over velocity, with mean 0). According to this model, brain circuitry encodes the expectation, acquired through sensory experience, that tactile stimuli tend to be stationary or to move only slowly. Ī Bayesian perceptual model closely replicates the cutaneous rabbit and other tactile spatiotemporal illusions. For details, see Goldreich & Tong (2013). Corresponding human data and Bayesian model fits are plotted in the lower panels. Stimuli are illustrated in the upper panels, along with their perception (forearm sketches). Perception underestimates the distance between successive taps to the skin. Explanation Ĭomputational models have been put forward by several authors in an effort to explain the origins of the cutaneous rabbit illusion. In keeping with the prediction of a Bayesian model, the perceptual attraction between the stimulus points is enhanced when the stimuli are made weaker. The device takes advantage of the cutaneous rabbit illusion to reduce the number of actuators needed. In 2009, researchers of Philips Electronics demonstrated a jacket lined with actuator motors and designed to evoke various tactile sensations while watching a movie. In addition, auditory and tactile stimuli can interact in the rabbit illusion. Visual cues-light flashes placed at particular locations along the arm-can influence the cutaneous rabbit illusion. The illusion has also been shown to occur both within and across the arms, suggesting that the illusion occurs after perceptual stages in the brain. However, a subpopulation of participants apparently does not experience the effect on the fingertips. Research has shown that the illusion can occur across non-contiguous body regions such as the fingers. This suggests that the cutaneous rabbit effect involves not only the intrinsic somatotopic representation but also the representation of the extended body schema that results from body-object interactions. When subjects supported a stick across their index fingertips and received the taps via the stick, they reported sensing the illusory taps along the stick. The illusion is not just confined to the "body". Many interesting instantiations of the cutaneous rabbit illusion have been observed. Nevertheless, the specific neural mechanisms that underlie the rabbit illusion are unknown. Another study showed that the illusory taps are associated with neural activity in the same area of the brain's sensory map that is activated by real taps to the skin. #Find the rabbit illusion skin#A study showed that attention directed to one skin location reduces the perceptual migration of a tap placed at the attended location. Studies have consistently shown that the rabbit illusion occurs only when successive taps are closely spaced in time the illusion disappears if the temporal separation between taps exceeds about 0.3 seconds (300 milliseconds). ![]() The word "saltation" refers to the leaping or jumping nature of the percept.įrom the moment of its discovery, the cutaneous rabbit illusion piqued the curiosity of researchers, and many experiments investigating the effect have been conducted, most of them on the forearm. While the rabbit illusion has been most extensively studied in the tactile domain, analogous sensory saltation illusions have been observed in audition and vision. Geldard and Sherrick likened the perception to that of a rabbit hopping along the skin, giving the phenomenon its name. The illusion was discovered by Frank Geldard and Carl Sherrick of Princeton University, in the early 1970s, and further characterized by Geldard (1982) and in many subsequent studies. Similarly, stimuli delivered first near the elbow then near the wrist evoke the illusory perception of taps hopping from elbow towards wrist. ![]() A rapid sequence of taps delivered first near the wrist and then near the elbow creates the sensation of sequential taps hopping up the arm from the wrist towards the elbow, although no physical stimulus was applied between the two actual stimulus locations. The illusion is most readily evoked on regions of the body surface that have relatively poor spatial acuity, such as the forearm. The cutaneous rabbit illusion (also known as cutaneous saltation and sometimes the cutaneous rabbit effect or CRE) is a tactile illusion evoked by tapping two or more separate regions of the skin in rapid succession. ![]()
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