Science explains why people perceive color differently

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A photograph of a cocktail dress went viral online recently after it had people divided on whether the dress was actually white with a gold lace trim, or blue with a black lace trim. The dress, designed by British clothing company, Roman, is in reality royal blue with black lace trim.

However, many people who saw the picture of the dress — which was photographed in odd lighting conditions — saw the garment as white and gold. Scientists have now weighed in with an explanation.

When light enters a person’s eyes through through the lens, it hits the retina in the back of the eye where pigments stimulate neural connections to the visual cortex. The visual cortex is the part of the brain that processes signals into an image. A person’s brain determines what colour light is reflecting off the objects the person is trying to see, and subtracts that colour from the genuine color of the object.

This is how people are able to determine a constant color of an object even when the lighting conditions continually change. The brain uses reference points from the colours around the object, the colour and brightness of light and previous knowledge to determine the actual colour of the object. This is called colour constancy.

However, in the case of the photograph of the dress, some experts say the light source and colour is ambiguous, which has caused different people to perceive the colour of the dress differently.

“What’s happening here is your visual system is looking at this thing, and you’re trying to discount the chromatic bias of the daylight axis,” Wired quoted Bevil Conway as saying.

Conway, a neuroscientist who studies color and vision at Wellesley College, added, “So people either discount the blue side, in which case they end up seeing white and gold, or discount the gold side, in which case they end up with blue and black.”

Conway, for his part, sees blue and orange.

RUNDOWN SHOWS:
1. Lightwaves entering the eyeball
2. Demonstration of how lighting changes throughout the day
3. Perceived overexposure
4. Perceived underexposure

VOICEOVER (in English):

“Lightwaves enter the eyes and activate cones and rods, which allow people to interpret color based on how the light is perceived — this is called color constancy.”

“Based on visual cues and previous knowledge, the eye determines the correct color of objects even when lighting is constantly changing.”

“Someone who perceives this scene as overexposed may have activated cones, which are sensitive to reds, greens and blues. This perceived overexposure is compensated by the brain assuming the ball is a darker shade of blue. Someone who perceives this scene as underexposed may have activated rods, which are sensitive to the colors black and white. This perception is compensated by the brain removing the darker shades from the image, thus causing the ball to appear whiter.”

“Someone who decided the dress was brightly illuminated may have assumed it was made of darker fabrics such as blue and black. However, if someone decided there was only dim illumination, their brain may have thought the dress was reflecting a lot of the light falling on it, in which case it must be made of more reflective fabrics, such as white and gold."

SOURCES:
Wired, Yahoo, National Geographic, The Guardian, Vox
http://www.wired.com/2015/02/science-one-agrees-color-dress/

https://www.yahoo.com/health/what-thedress-color-you-see-says-about-you-112243093272.html

http://news.nationalgeographic.com/news/2015/02/150227-blue-white-dress-optical-illusion-science/

http://www.theguardian.com/science/head-quarters/2015/feb/27/the-dress-blue-black-white-gold-vision-psychology-colour-constancy

http://www.vox.com/2015/2/27/8119901/explain-color-dress