Illusion - Tactile illusions
What is illusion?
It is the instance of a wrong or misinterpreted perception of a sensory experience.
* Sensation & Perception
- Optical (visual) illusions
- Auditory (hearing) illusions
- Tactile (touching) illusions
Tactile illusions
Tactile illusions are illusions that distort the sense of touch.
- Active touch
- Induced passively
Why study illusion?
Today's experiments
- Active touch
e.g. Aristotle illusion
- Induced passively
e.g. Distance misjudgment
-Practical Use
-Understand the
sensory mechanism
-Valid and challenge a theory
Aristotle illusion
- One of the oldest tactile illusion
- First described by Aristotle in the essay On Dreams
- Tactile diplopia (diplesthesia) on the human fingers (Benedetti, 1985)
Experiment
- Cross the middle and index fingers
- Close your eyes
- Partner puts 1/2 stick(s) in between your crossed fingers
- Guess how many sticks are there
Explanation
When the fingers are beyond the limit of the voluntary movement, sensation of the stimulus is referred back to the limiting position, where achieves with voluntary muscular effort
Explanation
Summary
- Neuromuscular apparatus activities
- Spatial location of the stimulus is perceived in the natural limit position
Distance Misjudgment
- Proposed by Weber (1978)
- Related to the different acuity level of different skin region
Experiment
- Illusion is the distortion of reality
due to the misinterpretation
- Aristotle illusion:
Neuromuscular apparatus limitations
- Distance misjudgment: receptor
- Relax, and give your hand to your partner
- Close your eyes
- Your partner will put the paperclip on different regions of your hand
- Guess if the distance of the paperclip is changed
Explanation
Taylor-Clarke, Jacobsen & Haggard (2004)
- (2008-01-01). Aristotle's illusion. In . : . Retrieved 8 Oct. 2013, from http://www.oxfordreference.com/view/10.1093/oi/authority.20110803095423799.
- Benedetti, F. (1985). Tactile Diplopia (diplesthesia) on the human fingers. Journals of Experimental Psychology: Human Perception and Performance, 11(4), 517-525.
- Pasquinelli, E. (2005). Aristotle's illusion [PPT document]. Retrieved from : elenapasquinelli.free.fr/links/Pasquinelli_2005_Lyon.ppt
- Taylor-Clarke, M., Jacobsen, P., Haggard, P. (2004). Keeping the world a constant size: object constancy in human touch. Nat Neurosci, 7(3), 219–220.
- Weber, E.H. (1978). The Sense of Touch. London: Academic.