Optical Illusions: Tricks of Perception

Introduction

• Optical illusions: Intersection of science and art.
• Aim to explore mechanisms of perception and what illusions reveal about the mind.

Horizontal and Vertical Line Illusion

• Two identical lines appear different in length.
• Horizontal line underestimated due to elongated visual field.
• Experiments with binocular vision.

Müller-Lyer Illusion

• Created by Franz Karl Müller-Lyer.
• Lines with arrow tips appear different in length but are identical.
• Cultural vs innate perception debate.
• Studies by Marshall Segal and Carpenter hypothesis: urban environments influence perception.

Delboeuf Illusion

• Surrounding stimuli influence perceived size.
• Assimilation and contrast effects.
• Impact on food serving sizes and eating behaviors.

Ponzo Illusion

• Perception of size altered by converging lines.
• Creates illusion of depth, affecting size judgment.

Zollner Illusion

• Parallel diagonal lines appear non-parallel due to intersecting lines.

Cafe Wall Illusion

• Discovered by Steve Simpson and Richard Gregory.
• Parallel rows appear misaligned due to tile pattern and luminance transitions.

Hering Illusion

• Lines appear bowed due to optic flow.
• Effect related to predicting future perception.

Impossible Objects and Ambiguity

• Necker Cube and Penrose Shapes.
• Interpretations of images can change, highlighting visual ambiguity.
• Connection to strange loops and self-reference.

Figure-Ground Illusions

• Ambiguous images like Rubin's Vase and Spinning Dancer.
• Perception influenced by figure-ground relationship.

Phantom Shapes and Gestalt Principles

• Kinesa Triangle and Ehrenstein illusion.
• Law of Closure: mind fills in missing information to perceive complete shapes.

Motion Illusions

• Peripheral drift illusion based on eye movements.
• Scintillating phenomena and microsaccades.
• Sliding illusions using retinal slip.
• Motion aftereffect described by Aristotle.

Conclusion

• No unifying theory of illusions but highlight perception's imperfection.
• Illusions reveal how humans interpret visual information, often imperfectly.

Additional Notes

• Illusions used in practical applications and studies.
• Patreon plug for extra content and support opportunities.