An fMRI study of the reverse perspective illusion.

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Psychology

Background:

• The reverse perspective (RP) illusion creates a false sense of motion in static images.
• This illusion arises from conflicting depth cues, specifically motion parallax and pictorial depth cues in 3D relief paintings.

Purpose of the Study:

• To measure brain activation using fMRI in response to RP stimuli.
• To compare brain responses to RP objects with normal perspective 3D-relief (shadow-box, SB) objects and 2D paintings.

Main Methods:

• fMRI was used to scan 10 subjects viewing static and rotating RP, SB, and 2D stimuli.
• Activation in area MT was observed for all stimuli conditions.
• Contrasts were performed between RP, SB, and 2D conditions, as well as between static and rotating conditions.

Main Results:

• All stimuli (RP, SB, 2D) showed strong activation of area MT.
• RP stimuli elicited significantly stronger activation than SB and 2D stimuli.
• Brain activation for SB and 2D stimuli showed minimal differences, suggesting normal perception of 3D depth in 2D images.
• RP stimuli, compared to SB or 2D, activated Brodmann Areas 7, 19, MT, and cerebellar cortex.

Conclusions:

• The visual system processes 2D images with realistic 3D depth similarly to actual 3D objects.
• The reverse perspective illusion uniquely engages brain regions associated with mental rotation and depth perception.
• Area MT is crucial for processing visual motion cues, regardless of perspective type.