Today, 5 years ago, “the dress” broke online, and we have come a long way since then. If nothing else, this is a scary reminder of how fast time passes while one is busy doing other things.
There were lots of clickbaity “explanations” of the phenomenon (like women having 4 cones) offered immediately, whereas others dismissed the phenomenon as being just another example of mass hysteria, the phenomenon, suggesting that there is nothing to see here, as this just reflects the impact of different screen settings.
Some (including us) realized that this is a completely novel phenomenon (displays like rubin’s vase or the duckrabbit are bistable within people, this is bistable *between* people, or within the population. Most people cannot switch the percept spontaneously). We also pointed out that we don’t know what is going on.
It took 2 years to establish that. Basically, it depends on what you believe about the illumination. And that depends on your experience. In cases where there is uncertainty about the illumination (as in this photo), these beliefs dominate the percept. As people have different experiences, they perceive different things: https://slate.com/technology/2017/04/heres-why-people-saw-the-dress-differently.html
After that, we realized that there are such phenomena for hearing (https://www.buzzfeednews.com/article/virginiahughes/yanny-laurel-audio-conspiracy-theory) and other visual stimuli (like the sneakers). The field also established other parameters that matter, i.e. the impact of pupil size on the individual percept, or how fast people change their mind.
What was left to do was to be able to *create* such a stimulus at will. It is most compelling to say that one understands the phenomenon when one can create it in a principled fashion. We have now done that as well: Using crocs, of all things.
Using crocs might sound – on the surface of it – even more ridiculous than the dress, but there is a deep principle (which we call SURFPAD) at work: Whenever you combine Substantial Uncertainty with Ramified or Forker Priors or Assumptions, you will get disagreement.
In the case of the crocs, this means to take an item (like crocs) that could be any color and put it on a black background to take away context cues. Then shine a complementary light on it to make it appear grey. But also include an item (such as the white socks) that will reflect the light. So objectively, there are grey crocs and green socks. But those who know from prior experience that the socks are actually white will mentally subtract that, and they perceive the original color of the crocs and white socks.
This is critical to understand our polarized times. To give an example from journalism: Say I wrote a piece on how someone is incompetent. But if you don’t know me or that person, you do not know whether that person is truly incompetent, or if I’m just being mean. Some people know that anyone can be put in a bad light, so if your prior belief is that the author is biased, the piece will be ineffective. Other people have a prior belief that the person is actually incompetent, so they will believe the author. Both kinds of people walk away feeling that their position has been confirmed by the ambiguous evidence, deepening the difference in priors, furthering the divide.