Two hands, one perception: how bimanual haptic information is combined by the brain

Area of Science:

• Neuroscience
• Haptic Perception
• Human Motor Control

Background:

• Humans utilize bimanual (two-handed) exploration for object shape and texture perception.
• The neural mechanisms for integrating haptic information from two hands remain largely unknown.

Purpose of the Study:

• To investigate whether the brain integrates haptic information from both hands during object contour exploration.
• To determine if bimanual exploration enhances haptic precision compared to unimanual exploration.

Main Methods:

• Participants (n=20) explored virtual curved contours using a robotic manipulandum with one or both hands.
• Psychophysical discrimination thresholds for curvature were measured under uni- and bimanual conditions.
• Bayesian perception theory and maximum-likelihood estimation (MLE) models were used for prediction.

Main Results:

• Haptic sensitivity varied between hands, with a left-hand bias observed in most participants.
• Bimanual thresholds were generally within the range of unimanual thresholds, not superior as predicted by MLE.
• Curvature perception was biased towards the motorically dominant hand, irrespective of haptic sensitivity.

Conclusions:

• Two-handed exploration did not consistently improve haptic precision for curvature discrimination.
• Evidence suggests a 'sensory selection' mechanism, favoring the dominant hand's input over integration.
• The brain may prioritize information from the dominant hand, even if the non-dominant hand is more sensitive.