Technical Note: Bells and Smells and Replication

How to replicate the analyses in “Bells and smells…” (more…)


The errors in my answer to Darwin

How the humble lab rat can teach you to raise your kids smarter and grow old gracefully

The importance of knowing how to look
Today, Charles Darwin is largely known for his theory of natural selection. Yet although his status as a scientific legend is assured, the nature of his fame does him an injustice. Darwin was not a theorist in the modern sense. First and foremost, he was a brilliant observer, and his extraordinary gift for observation is, more often than not, hugely underappreciated.

While the difficulty of observation is easily overlooked, it has become abundantly clear that we do not perceive the world ‘objectively’ (indeed, as Borges’ ingenious tale of the one-to-one map of the world reminds us, objectivity is a tricky idea at the best of times). Instead, our brains invent their perception of the world, inferring the nature of reality by means of a variety of processes based on of guessing and learning. For better or for worse we are theorists by nature, and the unreliability of perception is one of the reasons why we do science in the first place. It is also why observation is such a vital – and very difficult – scientific skill. Our facility to observe in an ‘objective-like’ fashion – consciously resisting the temptation to interpret every observation in accord with our minds’ prior expectations – is one of the great intellectual achievements of our species.

A prime example of Darwin’s genius for observation is found in his little-known contributions to the study of child psychology. Aside from his other well-documented achievements – and despite suffering from chronic illness throughout his adult life – Darwin not only fathered ten children, but even more remarkably, he found time to be a wonderful, engaged dad in an age when fathers were typically distant.

Darwin kept detailed diaries of the observations he made as his kids grew, and as a result of these we know that he may be the first person to ever notice a simple, yet deeply puzzling phenomenon that has tended to pass just about every other parent by: the bafflingly long time it takes kids to learn the meanings of color words. (more…)

Learning is not what you think it is

Why much of what you think you know about learning is likely to be wrong 
Ever since Ivan Pavlov (an endocrinologist with a particular interest in dog drool) made his famous observations about bells and dog-food, we have known that animals can be conditioned to respond to pairings of cues and events. Ring a bell every time you feed your dog, and you’ll soon be seeing some disappointed drooling whenever the doorbell chimes.

Pavlov, and other early students of learning, assumed that because a dog learns to associate a bell with its dinner after the two have been paired together, then this kind of learning was the product of a simple process of tracking and forming associations. The dog sees or hears one thing, then sees or hears another thing, it notices that they “go together” and, voila! Learning occurs.

Unfortunately, not only is does it turn out that this common understanding of how animals — or, indeed humans — learn associations is completely wrong, but to the consternation of Robert Rescorla, who did a lot of the important work in figuring out how animals actually do learn form to form associations, half a century after the simple associative account of learning was shown to be utterly incorrect, most psychologists and neuroscientists are still taught to believe that this is how animals — and, indeed humans — learn. In the light of this, our recent work showing that scientific accounts of cognitive ageing have spectacularly failed to consider the impact on learning on cognitive processing has a grim inevitability about it. How can scientists control for learning if their training ensures that they fail to understand what it is?

The problem runs deep. As a number of ingenious experiments by Rescorla and other researchers’ studies have helped make clear, most people’s — and, what is worse, most scientists’ — understanding of the way associative learning works is pretty much the opposite of our best estimation of the truth.

In my last post, I promised to provide more in-depth coverage of our aging work. On reflection, I realized that unless I made some kind of effort to explain what our best understanding of how our brains learn is, then our explanations of what actually happens to our minds and memories as we age would be difficult, if not impossible to grasp. This post — and my next — are intended to bridge this gap, by helping you to understand why it is that learning almost certainly doesn’t work the way you think it does, and by helping you to understand how it actually does work. Today, I’m mainly going to focus on the first part of the equation: I’m going to explain why, if you think that learning associations is about putting two and two together, then a lot of that stuff you think you know about learning is wrong.


Cognitive Ageing or Cognitive Decline? An FAQ

It is gratifying to see that our article, The myth of cognitive decline, has received a fair amount of attention in the past few weeks, because, as we point out in the paper, figuring out exactly what happens to our minds and memories in healthy ageing is of real importance, both at an individual and a societal level.

In a recent post, distinguished ageing researcher Patrick Rabbitt attacked the central thesis of our article – namely, that the evidence for cognitive decline in hea lthy minds is weak, and that the methods used to argue that our cognitive abilities decline critically fail to account for the growing information processing loads that experience brings. His take:

[The] feel-good news that slowing of decisions on all tasks is not a defining symptom of progressive failure but an honourable distinction of an age-stocked mind has eagerly excited the media (Telegraph; Guardian; BBC World Service; New York Times), but not researchers on cognitive aging.

For perfectly human reasons, it is hardly surprising that our work has failed to get researchers on cognitive ageing as “eagerly excited” as other folks. As Professor Rabbitt makes clear, no one likes to be told they are doing things wrong.

The important question is: are researchers on cognitive ageing doing things wrong?

What happens to our minds and memories in healthy ageing?

In our recent paper, The myth of cognitive decline, my colleagues and I suggest that the answer to this question is, “it’s complicated.” And if you think that the answer involves a steady deterioration of cognitive function, we present a series of findings that may make you think again.

Take, for instance, our ability to “retrieve” words from our memories: It’s widely believed that this ability declines as we get older. However, when we took a close look at the tests used to measure memory performance across the lifespan, we found that the truth of the matter is far less simple. Whether a word becomes harder (or easier) to recall with age can depend both on the kind of word tested, and the kind of test used. While many people find names increasingly hard to recall as they get older, on some tests of word recall, memory retrieval is unaffected by ageing. On other tests, performance actually improves with age. (I’ll talk more about this in more detail in a later post, but for now, Mark Liberman over at Language Log offers a lucid introduction to the way retrieval performance varies by test).

Not only did we find that a researcher’s choice of test can determine whether cognitive functioning appears to decline or improve with age, we also found that the results of the same cognitive test can suggest age-related declines or improvements, simply as a result of the context in which people are tested.

The methods we use to establish our findings are fairly complicated. For our journal article, we assumed that our readers would have a fairly high degree of scientific training, and so we kept the presentation of our methods and results brief. Because our results are likely to be of interest to people who have not had that training, I thought it might be helpful to write some expanded introductions to our work, so that our findings and their implications can be more widely understood.