Cutaneous rabbit illusion
Encyclopedia
The cutaneous rabbit illusion (also known as cutaneous saltation) is a tactile illusion
evoked by tapping two separate regions of the skin. Many experiments demonstrating the effect have been carried out on the forearm. 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. Similarly, stimuli delivered first near the elbow, then near the wrist, evoke the illusory perception of taps hopping from elbow towards wrist. The illusion was discovered by Frank Geldard and Carl Sherrick of Princeton University
, in the early 1970s (Geldard & Sherrick, 1972). They likened the perception to that of a rabbit hopping along the skin, giving the phenomenon its name.
From the moment of its discovery, the illusion has piqued the curiosity of researchers. A study showed that attention directed to one skin location modifies the perceived location of the illusory taps (Kilgard & Merzenich, 1995). Another study showed that the illusory taps are associated with neural activity in the same brain areas that are activated by real taps to the skin (Blankenburg et al., 2006). Nevertheless, the specific neural mechanisms that underlie the rabbit illusion are unknown. Neural models have been proposed by several authors (e.g., Flach & Haggard, 2006), and a recent Bayesian perceptual model replicates the rabbit illusion under the assumption that the brain expects tactile stimuli to move slowly (Goldreich, 2007).
In 2009, researchers of Philips Electronics demonstrated a jacket lined with actuator motors and designed to evoke various tactile sensations while watching a movie. The device takes advantage of the cutaneous rabbit illusion to reduce the number of actuators needed (Jones, 2009).
A group showed that this illusion is not just confined to the “body” (Miyazaki et al., 2010). When subjects held a stick such that it was laid across the tips of their index fingers and received the taps via the stick, they reported sensing the illusory taps along the stick. 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.
Touch illusion
Tactile illusions are illusions that exploit the sense of touch. Some touch illusions require active touch , whereas others can be evoked passively .-Examples:...
evoked by tapping two separate regions of the skin. Many experiments demonstrating the effect have been carried out on the forearm. A rapid sequence of taps delivered first near the wrist
Wrist
In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...
, and then near the elbow
Elbow
The human elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm....
creates the sensation of sequential taps hopping up the arm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
from the wrist towards the elbow, although no physical stimulus
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
was applied between the two actual stimulus locations. Similarly, stimuli delivered first near the elbow, then near the wrist, evoke the illusory perception of taps hopping from elbow towards wrist. The illusion was discovered by Frank Geldard and Carl Sherrick of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
, in the early 1970s (Geldard & Sherrick, 1972). They likened the perception to that of a rabbit hopping along the skin, giving the phenomenon its name.
From the moment of its discovery, the illusion has piqued the curiosity of researchers. A study showed that attention directed to one skin location modifies the perceived location of the illusory taps (Kilgard & Merzenich, 1995). Another study showed that the illusory taps are associated with neural activity in the same brain areas that are activated by real taps to the skin (Blankenburg et al., 2006). Nevertheless, the specific neural mechanisms that underlie the rabbit illusion are unknown. Neural models have been proposed by several authors (e.g., Flach & Haggard, 2006), and a recent Bayesian perceptual model replicates the rabbit illusion under the assumption that the brain expects tactile stimuli to move slowly (Goldreich, 2007).
In 2009, researchers of Philips Electronics demonstrated a jacket lined with actuator motors and designed to evoke various tactile sensations while watching a movie. The device takes advantage of the cutaneous rabbit illusion to reduce the number of actuators needed (Jones, 2009).
A group showed that this illusion is not just confined to the “body” (Miyazaki et al., 2010). When subjects held a stick such that it was laid across the tips of their index fingers and received the taps via the stick, they reported sensing the illusory taps along the stick. 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.