Similar Müller-Lyer effects from operant and comparison response modes

Area of Science:

• Psychology
• Visual Perception

Background:

• The Müller-Lyer illusion demonstrates how visual cues influence perceived length.
• Previous research indicates that specific fin-set configurations (concave vs. convex) lead to systematic over- or underestimation of line segments.

Purpose of the Study:

• To investigate whether the response mode affects metric distortion in the Müller-Lyer illusion.
• To compare the Operant Mode (marking a dot) with the Comparison Mode (judging equality) for assessing illusion effects.

Main Methods:

• Utilized a one-sided (monopole) Müller-Lyer illusion.
• Employed two response modes: Operant Mode and Comparison Mode.
• Analyzed the correlation between judgments obtained from both response modes.

Main Results:

• Judgments from the Operant Mode and Comparison Mode showed a very high correlation.
• Data from both modes closely fit a linear model.
• The linear model provided comparable index values for concave and convex fin-sets.

Conclusions:

• Motor demands of the Operant Mode do not introduce significant additional metric bias.
• The Operant Mode is a reliable and potentially more efficient method for assessing metric distortion in visual illusions.
• Results support the use of the Operant Mode for future research on perceptual distortions.