Actually, still no good explanation of ‘that dress’

The last time I almost went blind staring at “that dress” was thanks to Liz Hurley and on this occasion I find myself equally unsatisfied.

I’ll spare you the introduction about the amazing blue/black or white/gold dress. But what’s left me rather disappointed are the numerous ‘science of the dress’ articles that have appeared everywhere and say they’ve explained the effect through colour constancy.

Firstly, this doesn’t explain what we want to know – which is why people differ in their perceptions, and secondly, I don’t think colour constancy is a good explanation on its own.

To explain a little, colour constancy is an effect of the human visual system where colours are perceived as being different depending on their context as the brain adjusts for things like assumed lighting and surroundings. Here’s a good and topical example from XKCD. The dress colours are the same in both pictures but the seem different because the background colour is different.

An important feature of the visual system is that the experience of colour is not a direct result of the wavelength of the light being emitted by the surface. The brain modifies the experiences to try and ensure that things appear the same colour in different lighting because if we just went off wavelength everything would wildly change colour as it moved through a world which is lit unevenly and has different colour light sources.

Visual illusions take advantange of this and there are plenty of examples where you can see that even completely physically identical colours can be perceived as markedly different shades if the image suggests one is in shadow and the other in direct light, for example.

Firstly, this isn’t an explanation of why people differ in perceiving the dress. In fact, all of the ‘science explanations’ have simply recounted how perceived colours can change but not the most important thing which is why people are having two stable but contradictory experiences.

Colour constancy works on everyone with normal colour vision. If you take the panels from the XKCD cartoon, people don’t markedly disagree about what the perceived colours are. The effect of each image is very reliable between individuals.

That’s not the case with the dress. Also, if you say context makes a difference, changing the surroundings of the dress should change the colours. It doesn’t.

Some have argued that individual assumptions about lighting in the picture are what’s making the difference. In other words, the context is the unconscious assumptions people make about lighting in the picture.

But if this is the case, this still isn’t an explanation because it doesn’t tell us why people have different assumptions. Psychologists called these top-down effects or, if we’re going to get Bayesian, perceptual priors.

75% of people in this BuzzFeed poll said they saw white/gold, 25% said they saw blue/black, and a small minority of people say they’ve seen the picture ‘flip’ between the two perceptions. How come?

And there’s actually a good test of the colour constancy or any other other ‘implicit interpretation’ explanation. You should be able to create images that alter the visual system’s assumptions and make perception of the dress reliably flip between white/gold and blue/black, as with the XKCD cartoon.

So, any vision scientists out there who can come up with a good explanation of why people differ in their perceptions? Psychophysicists, have I gone wildly off track?

Spike activity 28-02-2015

Quick links from the past week in mind and brain news:

Nautilus magazine has a good piece on behavioural economics and rethinking ‘nudges’. Although the rethink is really just another form of standard ‘nudge’.

The biggest hedge fund in the world, the $165 billion Bridgewater, starts an AI team to help give it the edge on investments reports Bloomberg. Well, they couldn’t get much worse than humans.

Gizmodo reports that a neuroscientist says he’ll do a head transplant ‘real soon now’. Hungover neuroscientist reads Gizmodo, thinks ‘I said what!?!’

The UK’s Post Office head of marketing has clearly been taken in by neuromarketing who thinks it will help them “better understand” their customers. Just like the stamp while we scan your brain…

The New York Times reports on pharma company Shire doing the old ‘disease marketing by the way I have a pill for that’ trick with DSM-5 newcomer binge eating disorder.

Hard Feelings: Science’s Struggle to Define Emotions. Good piece in The Atlantic.

The Human Brain Project is to be reorganised after a bit of a fuss (Americans: a significant crisis).

Being a asshole boss is bad for team performance. Interesting piece in Harvard Business Review.

The smart unconscious

We feel that we are in control when our brains figure out puzzles or read words, says Tom Stafford, but a new experiment shows just how much work is going on underneath the surface of our conscious minds.

It is a common misconception that we know our own minds. As I move around the world, walking and talking, I experience myself thinking thoughts. “What shall I have for lunch?”, I ask myself. Or I think, “I wonder why she did that?” and try and figure it out. It is natural to assume that this experience of myself is a complete report of my mind. It is natural, but wrong.

There’s an under-mind, all psychologists agree – an unconscious which does a lot of the heavy lifting in the process of thinking. If I ask myself what is the capital of France the answer just comes to mind – Paris! If I decide to wiggle my fingers, they move back and forth in a complex pattern that I didn’t consciously prepare, but which was delivered for my use by the unconscious.

The big debate in psychology is exactly what is done by the unconscious, and what requires conscious thought. Or to use the title of a notable paper on the topic, ‘Is the unconscious smart or dumb?‘ One popular view is that the unconscious can prepare simple stimulus-response actions, deliver basic facts, recognise objects and carry out practised movements. Complex cognition involving planning, logical reasoning and combining ideas, on the other hand, requires conscious thought.

A recent experiment by a team from Israel scores points against this position. Ran Hassin and colleagues used a neat visual trick called Continuous Flash Suppression to put information into participants’ minds without them becoming consciously aware of it. It might sound painful, but in reality it’s actually quite simple. The technique takes advantage of the fact that we have two eyes and our brain usually attempts to fuse the two resulting images into a single coherent view of the world. Continuous Flash Suppression uses light-bending glasses to show people different images in each eye. One eye gets a rapid succession of brightly coloured squares which are so distracting that when genuine information is presented to the other eye, the person is not immediately consciously aware of it. In fact, it can take several seconds for something that is in theory perfectly visible to reach awareness (unless you close one eye to cut out the flashing squares, then you can see the ‘suppressed’ image immediately).

Hassin’s key experiment involved presenting arithmetic questions unconsciously. The questions would be things like “9 – 3 – 4 = ” and they would be followed by the presentation, fully visible, of a target number that the participants were asked to read aloud as quickly as possible. The target number could either be the right answer to the arithmetic question (so, in this case, “2”) or a wrong answer (for instance, “1”). The amazing result is that participants were significantly quicker to read the target number if it was the right answer rather than a wrong one. This shows that the equation had been processed and solved by their minds – even though they had no conscious awareness of it – meaning they were primed to read the right answer quicker than the wrong one.

The result suggests that the unconscious mind has more sophisticated capacities than many have thought. Unlike other tests of non-conscious processing, this wasn’t an automatic response to a stimulus – it required a precise answer following the rules of arithmetic, which you might have assumed would only come with deliberation. The report calls the technique used “a game changer in the study of the unconscious”, arguing that “unconscious processes can perform every fundamental, basic-level function that conscious processes can perform”.

These are strong claims, and the authors acknowledge that there is much work to do as we start to explore the power and reach of our unconscious minds. Like icebergs, most of the operation of our minds remains out of sight. Experiments like this give a glimpse below the surface.

This is my BBC Future column from last week. The original is here

Spike activity 20-02-2015

Quick links from the past week in mind and brain news:

Interesting social mapping using subway journey data from Beijing reproted in New Scientist.

BPS Research Digest has compiled a comprehensive list of mind, brain and behaviour podcasts.

That study finding a surge of p values just below 0.05 in psychology, probably not a sign of bad science, reports Daniel Lakens with a new analysis.

The Toronto Star reports that psychologists terminated a study on implanting false crime memories early due to over-effectiveness.

Why do mirrors seem to reverse left and right but not up or down? Clear explanation in a great video from Physics Girl.

Vice has an interesting piece on public reactions to celebrities who become psychotic or begin to display unusual behaviour.

Science News has a map of ambient noisyness is America.

There’s an interesting interview with Facebook AI director Yann LeCun in IEEE Spectrum magazine.

Anti-vax: wrong but not irrational


Since the uptick in outbreaks of measles in the US, those arguing for the right not to vaccinate their children have come under increasing scrutiny. There is no journal of “anti-vax psychology” reporting research on those who advocate what seems like a controversial, “anti-science” and dangerous position, but if there was we can take a good guess at what the research reported therein would say.

Look at other groups who hold beliefs at odds with conventional scientific thought. Climate sceptics for example. You might think that climate sceptics would be likely to be more ignorant of science than those who accept the consensus that humans are causing a global increase in temperatures. But you’d be wrong. The individuals with the highest degree of scientific literacy are not those most concerned about climate change, they are the group which is most divided over the issue. The most scientifically literate are also some of the strongest climate sceptics.

A driver of this is a process psychologists have called “biased assimilation” – we all regard new information in the light of what we already believe. In line with this, one study showed that climate sceptics rated newspaper editorials supporting the reality of climate change as less persuasive and less reliable than non-sceptics. Some studies have even shown that people can react to information which is meant to persuade them out of their beliefs by becoming more hardline – the exact opposite of the persuasive intent.

For topics such as climate change or vaccine safety, this can mean that a little scientific education gives you more ways of disagreeing with new information that don’t fit your existing beliefs. So we shouldn’t expect anti-vaxxers to be easily converted by throwing scientific facts about vaccination at them. They are likely to have their own interpretation of the facts.

High trust, low expertise

Some of my own research has looked at who the public trusted to inform them about the risks from pollution. Our finding was that how expert a particular group of people was perceived to be – government, scientists or journalists, say – was a poor predictor of how much they were trusted on the issue. Instead, what was critical was how much they were perceived to have the public’s interests at heart. Groups of people who were perceived to want to act in line with our respondents’ best interests – such as friends and family – were highly trusted, even if their expertise on the issue of pollution was judged as poor.

By implication, we might expect anti-vaxxers to have friends who are also anti-vaxxers (and so reinforce their mistaken beliefs) and to correspondingly have a low belief that pro-vaccine messengers such as scientists, government agencies and journalists have their best interests at heart. The corollary is that no amount of information from these sources – and no matter how persuasive to you and me – will convert anti-vaxxers who have different beliefs about how trustworthy the medical establishment is.

Interestingly, research done by Brendan Nyhan has shown many anti-vaxxers are willing to drop mistaken beliefs about vaccines, but as they do so they also harden in their intentions not to get their kids vaccinated. This shows that the scientific beliefs of people who oppose vaccinations are only part of the issue – facts alone, even if believed, aren’t enough to change people’s views.

Reinforced memories

We know from research on persuasion that mistaken beliefs aren’t easily debunked. Not only is the biased assimilation effect at work here but also the fragility of memory – attempts at debunking myths can serve to reinforce the memory of the myth while the debunking gets forgotten.

The vaccination issue provides a sobering example of this. A single discredited study from 1998 claimed a link between autism and the MMR jab, fuelling the recent distrust of vaccines. No matter how many times we repeat that “the MMR vaccine doesn’t cause autism”, the link between the two is reinforced in people’s perceptions. To avoid reinforcing a myth, you need to provide a plausible alternative – the obvious one here is to replace the negative message “MMR vaccine doesn’t cause autism”, with a positive one. Perhaps “the MMR vaccine protects your child from dangerous diseases”.

Rational selfishness

There are other psychological factors at play in the decisions taken by individual parents not to vaccinate their children. One is the rational selfishness of avoiding risk, or even the discomfort of a momentary jab, by gambling that the herd immunity of everyone else will be enough to protect your child.

Another is our tendency to underplay rare events in our calculation about risks – ironically the very success of vaccination programmes makes the diseases they protect us against rare, meaning that most of us don’t have direct experience of the negative consequences of not vaccinating. Finally, we know that people feel differently about errors of action compared to errors of inaction, even if the consequences are the same.

Many who seek to persuade anti-vaxxers view the issue as a simple one of scientific education. Anti-vaxxers have mistaken the basic facts, the argument goes, so they need to be corrected. This is likely to be ineffective. Anti-vaxxers may be wrong, but don’t call them irrational.

Rather than lacking scientific facts, they lack a trust in the establishments which produce and disseminate science. If you meet an anti-vaxxer, you might have more luck persuading them by trying to explain how you think science works and why you’ve put your trust in what you’ve been told, rather than dismissing their beliefs as irrational.

The Conversation

This article was originally published on The Conversation.
Read the original article.

Oliver Sacks: “now I am face to face with dying”

In a moving and defiant article for the The New York Times, neurologist Oliver Sacks has announced he has terminal cancer.

Over the last few days, I have been able to see my life as from a great altitude, as a sort of landscape, and with a deepening sense of the connection of all its parts. This does not mean I am finished with life.

On the contrary, I feel intensely alive, and I want and hope in the time that remains to deepen my friendships, to say farewell to those I love, to write more, to travel if I have the strength, to achieve new levels of understanding and insight.

This will involve audacity, clarity and plain speaking; trying to straighten my accounts with the world. But there will be time, too, for some fun (and even some silliness, as well).

The whole piece is a reflection on life, death and living and, fittingly, is a joy to read.

Keep on keepin’ on Dr Sacks.

We look forward to hearing about your final adventures.

Link to ‘My Own Life: Oliver Sacks on Learning He Has Terminal Cancer’.

Half a century of neuroscience

The Lancet has a good retrospective looking back on the last 50 years of neuroscience, which in some ways, was when the field was born.

Of course, the brain and nervous system has been the subject of study for hundreds, if not thousands, of years but the concept of a dedicated ‘neuroscience’ is relatively new.

The term ‘neuroscience’ was first used in 1962 by biologist Francis Schmitt who previously referred to the integrated study of mind, brain and behaviour by the somewhat less catchy title “biophysics of the mind”. The first undergraduate degree in neuroscience was offered by Amherst College only in 1973.

The Lancet article, by one of the first generation ‘neuroscientists’ Steven Rose, looks back at how the discipline began in the UK (in a pub, as most things do) and then widens his scope to review how neuroscience has transformed over the last 50 years.

But many of the problems that had beset the early days remain unresolved. Neuroscience may be a singular label, but it embraces a plurality of disciplines. Molecular and cognitive neuroscientists still scarcely speak a common language, and for all the outpouring of data from the huge industry that neuroscience has become, Schmitt’s hoped for bridging theories are still in short supply. At what biological level are mental functions to be understood? For many of the former, reductionism rules and the collapse of mind into brain is rarely challenged—there is even a society for “molecular and cellular cognition”—an elision hardly likely to appeal to the cognitivists who regard higher order mental functions as emergent properties of the brain as a system.

It’s an interesting reflection on how neuroscience has changed over its brief lifespan from one of the people who were there at the start.

Link to ’50 years of neuroscience’ in The Lancet.