Our brains construct reality

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Lecture 1

Our brains construct reality

“We don’t see things as they are, we see them as we are.” - Anaïs Nin

Objectives

  • Understand that perception is active construction, not passive recording
  • Explore how past experiences shape present perceptions
  • Discover why eyewitness accounts can differ dramatically
  • Examine how culture shapes our fundamental perception of reality

The Dress That Broke the Internet

The Phenomenon

The Dress


Do you see blue and black? White and gold? Why do you think this happens?

  • It a matter of the brain’s interpretation of what your eyes are seeing
  • Perception of reality is not the same thing as reality

  • The Dress phenomenon refers to a viral internet sensation from 2015 where a photograph of a dress sparked massive global debate about its colors. While some people perceived the dress as blue and black, others saw it as white and gold, with roughly equal numbers in each camp. This wasn’t simply a matter of opinion—people were genuinely seeing different colors in the identical image. The phenomenon occurs due to individual differences in how brains process ambiguous lighting information and make assumptions about the illumination source. When the brain interprets the dress as being in shadow, it compensates by perceiving lighter colors (white and gold), but when it interprets the dress as being in bright light, it sees the actual darker colors (blue and black). The Dress became a perfect real-world example of how individual brains construct different subjective realities from identical sensory input, demonstrating that perception is an active, interpretive process rather than a passive recording of objective reality.

  • Useful summary video:

The Science Behind It

  • Lighting assumptions: Your brain makes assumptions about the lighting conditions
  • Color constancy: How your visual system adjusts for different light sources
  • Individual differences: Age, screen settings, and personal color processing variations
  • Color constancy explanation:

The dress color constancy explanation.

  • Figure from: Brainard & Hurlbert, 2015
  • Linked paper here: https://www.sciencedirect.com/science/article/pii/S0960982215005941

🔬 Deep Dive: Color Constancy Explanation

The color constancy explanation for "The Dress" centers on how our brains automatically adjust for different lighting conditions to maintain stable color perception. Color constancy is a property where our visual system tries to make objects appear the same color under different lighting conditions by making assumptions about the illumination source and mentally "subtracting" or "discounting" the color cast of the light.

For The Dress specifically, the explanation works as follows: People who saw the dress as white and gold probably assumed it was lit by cool, bluish daylight, so their brains ignored shorter, bluer wavelengths. Those who saw it as blue and black assumed warm, artificial light, so their brains ignored longer, redder wavelengths.

The mechanism is that shadows are blue, so people who assume the dress is in shadow mentally subtract the blue light to view the image, which then appears in bright colors — gold and white. However, artificial light tends to be yellowish, so if people see it as brightened by artificial light, they factor out this yellow color, leaving a dress that appears black and blue.

Section 1: Your Brain as Reality Constructor

Core Concept: Perception isn’t Photography - It’s Painting

1.1 Change Blindness

Essential Videos :

  • Change Blindness in Real Life - The monkey study
  • Change Blindness in Real Life #2 - this video is better and gives a fantastic explanation
  • Change blindness is our failure to notice large changes in our visual environment. It occurs when changes happen during eye movements, brief interruptions, or gradual transitions
  • This phenomenon reveals the limitations of our visual attention and memory

Bigger picture:

  • You feel like you see everything clearly and completely - but you don’t
  • Your brain creates a rich, detailed experience from limited, fragmented information
  • This isn’t a bug in the system - it’s a feature that allows us to function efficiently
  • What you experience as “reality” is actually your brain’s best guess about what’s out there

Discussion Points:

  • Why didn’t participants notice the person changing?
  • What does this tell us about how much we actually “see”?
  • Real-world implications: driving, witnessing events

1.2 Perceptual priors – Mooney Images Demonstration

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