What colour is this handbag?

Remember that white-gold or black-blue dress debate last year that divided the internet? Taylor Corso (@whyofcorso) tweeted this image with the caption “Everyone say hello to my new baby.” Someone responded “White. Daring.” To which she replied “It’s blue.” So a new colour debate is born #mybag.

The bag is said to be ‘mystic blue’. And while the eyes themselves have differing ratios of short, medium and long wavelength cones (a photoreceptor cell responsible for seeing colour) amongst people and can cause subtle differences in how we each perceive colour, it is probably not enough to explain the dramatic differences in perception.

The most likely explanation is a phenomenon known as colour constancy. This is the ability to perceive colours of objects, invariant to the colour of the light source. So in this instance, a person’s perception of colour can be changed by its context and surroundings. An example is colour seen in daylight versus artificial light. Because we are unsure, our brain makes a judgement on colour without the correct information. Here is a great video by AsapSCIENCE explaining this phenomena.