information theory and psychology

I have read a good deal more about information theory and psychology than I can or care to remember. Much of it was a mere association of new terms with old and vague ideas. Presumably the hope was that a stirring in of new terms would clarify the old ideas by a sort of sympathetic magic.

From: John R. Piece’s 1961 An introduction to information theory: symbols, signals and noise. Plus ça change.

Pierce’s book is really quite wonderful and contains lots of chatty asides and examples, such as:

Gottlob Burmann, a German poet who lived from 1737 to 1805, wrote 130 poems, including a total of 20,000 words, without once using the letter R. Further, during the last seventeen years of his life, Burmann even omitted the letter from his daily conversation.

The two word games that trick almost everyone

270px-Cowicon.svgPlaying two classic schoolyard games can help us understand everything from sexism to the power of advertising.

There’s a word game we used to play at my school, or a sort of trick, and it works like this. You tell someone they have to answer some questions as quickly as possible, and then you rush at them the following:

“What’s one plus four?!”
“What’s five plus two?!”
“What’s seven take away three?!”
“Name a vegetable?!”

Nine times out of 10 people answer the last question with “Carrot”.

Now I don’t think the magic is in the maths questions. Probably they just warm your respondent up to answering questions rapidly. What is happening is that, for most people, most of the time, in all sorts of circumstances, carrot is simply the first vegetable that comes to mind.

This seemingly banal fact reveals something about how our minds organise information. There are dozens of vegetables, and depending on your love of fresh food you might recognise a good proportion. If you had to list them you’d probably forget a few you know, easily reaching a dozen and then slowing down. And when you’re pressured to name just one as quickly as possible, you forget even more and just reach for the most obvious vegetable you can think of – and often that’s a carrot.

In cognitive science, we say the carrot is “prototypical” – for our idea of a vegetable, it occupies the centre of the web of associations which defines the concept. You can test prototypicality directly by timing how long it takes someone to answer whether the object in question belongs to a particular category. We take longer to answer “yes” if asked “is a penguin a bird?” than if asked “is a robin a bird?”, for instance. Even when we know penguins are birds, the idea of penguins takes longer to connect to the category “bird” than more typical species.

So, something about our experience of school dinners, being told they’ll help us see in the dark, the 37 million tons of carrots the world consumes each year, and cartoon characters from Bugs Bunny to Olaf the Snowman, has helped carrots work their way into our minds as the prime example of a vegetable.

The benefit to this system of mental organisation is that the ideas which are most likely to be associated are also the ones which spring to mind when you need them. If I ask you to imagine a costumed superhero, you know they have a cape, can probably fly and there’s definitely a star-shaped bubble when they punch someone. Prototypes organise our experience of the world, telling us what to expect, whether it is a superhero or a job interview. Life would be impossible without them.

The drawback is that the things which connect together because of familiarity aren’t always the ones which should connect together because of logic. Another game we used to play proves this point. You ask someone to play along again and this time you ask them to say “Milk” 20 times as fast as they can. Then you challenge them to snap-respond to the question “What do cows drink?”. The fun is in seeing how many people answer “milk”. A surprising number do, allowing you to crow “Cows drink water, stupid!”. We drink milk, and the concept is closely connected to the idea of cows, so it is natural to accidentally pull out the answer “milk” when we’re fishing for the first thing that comes to mind in response to the ideas “drink” and “cow”.

Having a mind which supplies ready answers based on association is better than a mind which never supplies ready answers, but it can also produce blunders that are much more damaging than claiming cows drink milk. Every time we assume the doctor is a man and the nurse is woman, we’re falling victim to the ready answers of our mental prototypes of those professions. Such prototypes, however mistaken, may also underlie our readiness to assume a man will be a better CEO, or a philosophy professor won’t be a woman. If you let them guide how the world should be, rather than what it might be, you get into trouble pretty quickly.

Advertisers know the power of prototypes too, of course, which is why so much advertising appears to be style over substance. Their job isn’t to deliver a persuasive message, as such. They don’t want you to actively believe anything about their product being provably fun, tasty or healthy. Instead, they just want fun, taste or health to spring to mind when you think of their product (and the reverse). Worming their way into our mental associations is worth billions of dollars to the advertising industry, and it is based on a principle no more complicated than a childhood game which tries to trick you into saying “carrots”.

This is my BBC Future column from last week. The original is here. And, yes, I know that baby cows actually do drink milk.

Is there a child mental health crisis?

CC Licensed Image from Wikimedia Commons. Click for source.It is now common for media reports to mention a ‘child mental health crisis’ with claims that anxiety and depression in children are rising to catastrophic levels. The evidence behind these claims can be a little hard to track down and when you do find it there seems little evidence for a ‘crisis’ but there are still reasons for us to be concerned.

The commonest claim is something to the effect that ‘current children show a 70% increase in rates of mental illness’ and this is usually sourced to the website of the UK child mental health charity Young Minds which states that “Among teenagers, rates of depression and anxiety have increased by 70% in the past 25 years, particularly since the mid 1980’s”

This is referenced to a pdf report by the Mental Health Foundation which references a “paper presented by Dr Lynne Friedli”, which probably means this pdf report which finally references this 2004 study by epidemiologist Stephan Collishaw.

Does this study show convincing evidence for a 70% increase in teenage mental health problems in the last 25 years? In short, no, for two important reasons.

The first is that the data is quite mixed – with both flatlines and increases at different times and in different groups – and the few statistically significant results may well be false positives because the study doesn’t control for running lots of analyses.

The second reason is because it looked at a 25-year period but only up to 1999 – so it is now 17 years out-of-date.

Lots of studies have been published since then, which we’ll look at in a minute, but these findings prompted the Nuffield Foundation to collect another phase of data in 2008 in exactly the same way as this original study, and they found that “the overall level of teenage mental health problems is no longer on the increase and may even be in decline.”

Putting both these studies together, this is typical of the sort of mixed picture that is common in these studies, making it hard to say whether there genuinely is an increase in child mental health problems or not.

This is reflected in data reported by three recent review papers on the area. Two articles focused on data from rating scales – questionnaires given to parents, teachers and occasionally children, and one paper focused on population studies that use diagnosis.

The first thing to say, is that there is no stand-out clear finding that child mental health problems are increasing in general, because the results are so mixed. It’s also worth saying that even where there is evidence of an increase, the effects are small to moderate. And because there is not a lot of data, the conclusions are quite provisional.

So is there evidence for a ‘child mental health crisis’? Probably not. Are there things to be concerned about – yes, there are.

Here’s perhaps what we can make out in terms of rough trends from the data.

It doesn’t seem there is an increase in child mental health problems for young children, that is, those below about 12. If anything, their mental health has been improving over the since the early 2000s. Here, however, the data is most scarce.

Globally, and lumping all children together, there is no convincing evidence for an increase in child mental health problems. One review of rating scale data suggests there is an increase, the other paper using the more rigorous systematic review approach suggests not – in line with the data from the review of diagnostic studies.

However, there does seem to be a trend for an increase in anxiety and depression in teenage girls. And data from the UK particularly does seem to show a mild-moderate upward trend for mental health problems in adolescents in general, in comparison to other countries where the data is much more mixed. Again, though, the data isn’t as solid as it needs to be.

This leaves open some important questions though. If we’re talking about a crisis – maybe the levels were already too high so even a drop means we’re still at ‘crisis level’. So one of the most important questions is – what would be an acceptable level of mental health problems in children?

The first answer that comes to mind is ‘zero’ and not unreasonably – but considering that some mental health problems arise from largely unavoidable life stresses, bereavements, natural disasters and accidents, it would be unrealistic to expect that no child suffered periods of disabling anxiety or depression.

This also raises the question of where we decide to make the cut-off for ’emotional problems’ or ’emotional disorders’ in comparison to ‘healthy emotions’. We need anxiety, sadness and anger but they can also become disabling. Deciding where we draw the line is key in answering questions about child mental health.

So there is no way of answering the question about ‘acceptable levels of mental health problems’ without raising the question of the appropriateness of how we define problems.

Similarly, a very common finding is huge variation between countries and cultures. Concepts, reporting, and the experience of emotions can vary greatly between different cultural groups, making it difficult to make direct comparisons across the globe.

For example, the broadly Western understanding of anxiety as a distinct psychological and emotional experience which can be understood separately from its bodily effects is not one shared by many cultures.

It’s worth saying that cultural changes occur not only between peoples but also over times. Are children more likely to report emotional distress in 2016 compared to 1974 even if they feel the same? Really, we don’t know.

All of which brings us to the question- why is there so much talk about a ‘mental health crisis’ in young people if there is no strong data that there is one?

Partly this is because the mental health of children is often a way of expressing concerns about societal changes. It’s “won’t someone think of the children” given a clinical sheen. But it is also important to realise that consultations and treatment for child mental health problems have genuinely rocketed, probably because of greater awareness and better treatment.

In the UK at least, it’s also clear that talk of a ‘child mental health crisis’ can refer to two things: concerns about rising levels of mental problems, but also concerns about the ragged state of child mental health services in Britain. There is a crisis in that more children are being referred for treatment and the underfunded services are barely keeping their head above water.

So talk of a ‘crisis in rising levels of child mental health problems’ is, on balance, an exaggeration, but we shouldn’t dismiss the trends that the data do suggest.

One of the strongest is the rise in anxiety and depression in teenage girls. We clearly have a long way to go, but the world has never been safer, more equal and more full of opportunities for our soon-to-be-women. Yet there seems to be a growing minority of girls affected by anxiety and depression.

At the very least, it should make us think about whether the society we are building is appropriately supporting the future 50% of the adult population.

The memory trap

CC Licensed Photo by Flickr user greeblie. Click for source.I had a piece in the Guardian on Saturday, ‘The way you’re revising may let you down in exams – and here’s why. In it I talk about a pervasive feature of our memories: that we tend to overestimate how much of a memory is ‘ours’, and how little is actually shared with other people, or the environment (see also the illusion of explanatory depth). This memory trap can combine with our instinct to make things easy for ourselves and result in us thinking we are learning when really we’re just flattering our feeling of familiarity with a topic.

Here’s the start of the piece:

Even the most dedicated study plan can be undone by a failure to understand how human memory works. Only when you’re aware of the trap set for us by overconfidence, can you most effectively deploy the study skills you already know about.
… even the best [study] advice can be useless if you don’t realise why it works. Understanding one fundamental principle of human memory can help you avoid wasting time studying the wrong way.

I go on to give four evidence-based pieces of revision advice, all of which – I hope – use psychology to show that some of our intuitions about how to study can’t be trusted.

Link: The way you’re revising may let you down in exams – and here’s why

Previously at the Guardian by me:

The science of learning: five classic studies

Five secrets to revising that can improve your grades