A size illusion from simultaneous changes in length and direction of a line pattern

Area of Science:

• Visual perception
• Psychophysics
• Depth perception

Background:

• Dynamic visual stimuli can elicit depth perception.
• Previous research established that specific configurations of moving lines induce a sense of depth.

Purpose of the Study:

• To investigate the effect of a depth-inducing visual configuration on the perceived size of a target object.
• To quantify the perceived size difference between a target object within and outside the depth-inducing stimulus.

Main Methods:

• A circle was presented attached to simultaneously changing lines (length and direction).
• This dynamic configuration was previously shown to induce depth perception.
• Observers compared the apparent size of a moving circle within the configuration to a stationary, physically equal circle outside the configuration.

Main Results:

• 20 out of 26 observers perceived the moving circle as smaller than the stationary comparison circle.
• A significant majority of participants experienced a size underestimation for the object within the depth-inducing display.

Conclusions:

• The perception of depth induced by moving lines can lead to a corresponding underestimation of object size.
• This finding suggests an interaction between depth cues and size constancy mechanisms in visual perception.