The hand-reversal illusion revisited.

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Motor Control

Background:

• The hand-reversal illusion is a visuomotor phenomenon where cross-folding hands leads to erroneous finger lifting.
• Previous research attributed this illusion to visual-proprioceptive conflict, as it disappears with eyes closed.

Purpose of the Study:

• To re-evaluate the visual-proprioceptive conflict hypothesis of the hand-reversal illusion.
• To investigate the role of reaction time (RT) in understanding the illusion's mechanisms.

Main Methods:

• Reaction time measurements were obtained to assess performance.
• The experiment involved cross-folding hands and testing finger lifting with and without visual input.
• Impairment was assessed using single-hand testing to rule out left-right confusions.

Main Results:

• Motor impairment, indicated by delayed response times (RTs), persisted even when visual input was absent.
• The impairment was observed even when only one hand was tested, excluding left-right confusion as the primary cause.
• These findings challenge the sole reliance on visual-proprioceptive conflict to explain the illusion.

Conclusions:

• The hand-reversal illusion is not solely explained by visual-proprioceptive conflict.
• The unusual spatial configuration of reversed hands contributes to the impaired motor response.
• Further research should consider the role of spatial representation in this visuomotor illusion.