00 · IN THREE MINUTES
The answer in three steps
- 1A motor command is accompanied by an internal prediction of the expected touch.
- 2The predicted sensation is compared with incoming sensory signals.
- 3A close match reduces the response; an unexpected delay or trajectory restores some ticklishness.
01 · ACTION COMES WITH A FORECAST
Action comes with a forecast
Motor-control systems use an of the command to estimate where the body will move and what sensations the movement should create.
02 · MATCHING INPUT IS ATTENUATED
Matching input is attenuated
When the actual touch arrives at the predicted time and place, sensory processing is reduced. This helps the nervous system emphasize changes likely to come from the outside world.
Action comes with a forecast
Motor-control systems use an efference copy of the command to estimate where the body will move and what sensations the movement should create.
motor commandMatching input is attenuated
When the actual touch arrives at the predicted time and place, sensory processing is reduced. This helps the nervous system emphasize changes likely to come from the outside world.
forward modelDelay breaks the prediction
Experiments using robotic devices show that adding a temporal delay or changing the spatial mapping makes self-produced touch feel more ticklish. The mismatch defeats precise cancellation.
prediction errorThe cerebellum helps compare
Imaging and lesion evidence implicate cerebellar circuits in predicting sensory consequences and distinguishing self-generated from externally generated events.
attenuation03 · DELAY BREAKS THE PREDICTION
Delay breaks the prediction
Experiments using robotic devices show that adding a temporal delay or changing the spatial mapping makes self-produced touch feel more ticklish. The mismatch defeats precise cancellation.
04 · THE CEREBELLUM HELPS COMPARE
The cerebellum helps compare
Imaging and lesion evidence implicate cerebellar circuits in predicting sensory consequences and distinguishing self-generated from externally generated events.
05 · TICKLING IS MORE THAN LIGHT TOUCH
Tickling is more than light touch
Different kinds of tickle recruit reflex, social and emotional responses. Prediction explains why self-tickle is weak, not every reason laughter and vulnerability accompany another person's touch.
06 · SOURCES AND EVIDENCE
Sources and evidence
The explanation follows the evidence chain below. Links open the original source.
- 01Central cancellation of self-produced tickle sensationPRIMARY STUDY ↗
Supports a specific claim or evidence boundary used in this article.
- 02The cerebellum predicts the sensory consequences of actionPRIMARY STUDY ↗
Supports a specific claim or evidence boundary used in this article.
- 03Why can't you tickle yourself?INSTITUTIONAL EXPLAINER ↗
Supports a specific claim or evidence boundary used in this article.