Gaze Direction Changes the Vertical-Horizontal Illusory Effects on Manual Length Estimations.

Area of Science:

• Psychology
• Neuroscience
• Perception

Background:

• The vertical-horizontal (V-H) illusion demonstrates a perceptual bias where a vertical line appears longer than an equal-length horizontal line.
• This illusion can affect visual perception and potentially influence motor control.
• Understanding these influences is crucial for sensorimotor coordination research.

Purpose of the Study:

• To investigate how the V-H illusion affects manual length estimations.
• To determine the role of gaze direction in mediating the V-H illusion's impact on perceptuomotor control.
• To explore the exploitation of deceptive visual cues in upper limb control.

Main Methods:

• Participants manually estimated the length of the bisecting segment of V-H illusion configurations.
• Gaze direction was manipulated: free, on the configuration, or on the movement space.
• Configurations were presented in upright and rotated orientations.

Main Results:

• Manual length estimations were significantly influenced by gaze direction.
• The V-H illusion's deceptive effects on manual estimation were observed only under restricted viewing conditions (gaze on configuration or movement).
• Perceptuomotor control was modulated by the illusion when deceptive visual cues were directly attended.

Conclusions:

• The V-H illusion's influence on manual length estimation is dependent on attentional focus, specifically gaze direction.
• Sensorimotor coordination can be guided by deceptive visual cues when attention is directed appropriately.
• This highlights the intricate relationship between visual perception, attention, and motor execution.