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Limb apparent motion perception: Modification by tDCS, and clinically or experimentally altered bodily states
Gianluca Saetta1, Jasmine T Ho2, Robin Bekrater-Bodmann3
1Department of Psychology, University of Zurich, Switzerland; Department of Experimental Psychology, Utrecht University, the Netherlands.
Neuropsychologia
|October 2, 2021
Summary
The motor theory of limb apparent motion perception (LAMP) was supported by two studies. Sensorimotor state changes influenced perception of possible movements, especially in amputees and able-bodied individuals.
Area of Science:
- Neuroscience
- Perceptual Psychology
- Motor Control
Background:
- Limb apparent motion perception (LAMP) is an illusory visual phenomenon.
- The motor theory posits that perception of physically possible movements relies on sensorimotor representations.
- Stimulus onset asynchrony (SOA) influences whether perceived motion is possible or impossible.
Purpose of the Study:
- To test the motor theory of LAMP by manipulating sensorimotor states.
- To investigate the role of sensorimotor representations in LAMP.
Main Methods:
- Study 1: Used cathodal transcranial direct current stimulation (tDCS) to dampen left sensorimotor cortex activity.
- Study 2: Examined LAMP in individuals with lower limb amputation (with/without prosthesis), body integrity dysphoria (BID), and able-bodied individuals under altered sensorimotor conditions.
Main Results:
- Cathodal tDCS biased LAMP towards perceiving impossible movements at slow SOAs.
- Momentary sensorimotor state significantly impacted LAMP in amputees and able-bodied participants.
- LAMP was not affected by sensorimotor state manipulation in individuals with BID.
Conclusions:
- The findings provide evidence for the motor theory of LAMP.
- Sensorimotor states play a crucial role in how we perceive limb movement, particularly for physically possible motions.
