Some time ago a photo of a striped dress has become a dress of discussion over the internet, arousing tough arguments about what color is the dress. As it turned out, there are at least two different answers to this question. One camp stated that the dress was blue and black, while their opponents believed it was white and gold. The final mark in this fishy story was made by scientists that had to interfere into the dress issue. But before we get down to it, let us try to understand how we percieve colors and why people virtually interpreted the color of the dress differently.
When it comes to color perception, it depends on the wavelengths that hit the retina in the back of our eyes. Then the wavelengths are analyzed by the visual cortex. That is where neural signals are transformed into an image. “Our visual system is supposed to throw away information about the illuminant and extract information about the actual reflectance,” says Jay Neitz, a neuroscientist at the University of Washington.
In other words, in the interpretation of colors there are two parties involved – the eye (retina) and the brain (cortex). Hence, there is an effect described back in 1971 by Edwin H. Land, who formulated a so-called “retinex theory” derived from the blend of words retina and cortex.
The experiment was about showing a specific display consisting of various colored patches to a person. The display is illuminated by three white lights and each of them is projected through red, green and blue filters. So first the person is asked to adjust filters’ intensity so that a particular patch appears white, while the experimenter writes down all the measurements. Then the person is asked to select the patch of particular color, and the experimenter adjusts all filters to the white patch measurements (what a trick!).
But the person stubborn insists that the patch is green against all manipulations. That is actually how color constancy works. Human beings tend to perceive colors of the same objects in the same way regardless of the illumination conditions. It serves us in identification of the objects and recognize them as familiar. Apple is apple, right?
But still what happened with the dress?
Again, even a researcher with a 30-year experience in color vision, the case has become “one of the biggest individual differences ” she has ever seen.
What we are missing here, is that daylight itself is inconsistent in terms of colors. The dawn is ablaze in red and pink while noon is bluish, and again as the morning kicks in it turns into red and orange.
“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,” says Bevil Conway, a neuroscientist who studies color and vision at Wellesley College. “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.”
So here is new study’s results, which was conducted by German researchers. Lara Schlaffke and her colleagues used special functional magnetic resonance imaging (fMRI) to monitor brain activity of 28 people with normal vision while they looked at the photo of the dress. Half of them saw the dress as white and gold, and another half saw it as blue and black. There is nothing new in such antagonism, except for one interesting observation.
The brain activity of the white and gold group indicated significant spikes in several areas of brain such as frontal, parietal and temporal, which evidently states that their overall cognition was higher. So what is the clue? The clue is in how we perceive the environment. Our attention can be distinctly influenced either by external or internal attention.
When our attention is mainly driven by the external stimulus, we are involved in bottom-up processing. In other words, we follow the way of the least resistance. But when we are capable to get away from it involving interpretative processing, it is called a top-down modulation. As stated in Dr. Adam Gazzaley’s research publications, “Top-down modulation is a bi-directional process in that it underlies our ability to both focus our attention on task-relevant stimuli and ignore irrelevant distractions.”
To simplify it, it is an ability of our brain to cut off excessive information from the very essence.
But where you are in the “right” group of blue and black, or “wrong” perceivers, there is still a cause-effect puzzle – if the perception of the dress caused extra activity of neurons or resulted in it. To see or not to see, that is the question.