Thursday, 30 June 2011

Blocking in Learning

Sometimes I stumble across a really simple concept that I feel like I should have known, and perhaps even at one point did know. "Blocking" is just one of those concepts, which I found in David Shanks' Annual Review of Psychology paper Learning: From association to cognition.

The basic idea is pretty simple. In classical conditioning, when a neutral stimulus is presented alongside an unconditioned stimulus that generates an unconditioned response, that neutral stimulus normally becomes a conditioned stimulus that causes a conditioned response. The classic example is, quite obviously, Pavlov's dogs; the smell of food (US) caused salivation (UR). When a bell was rung (NS) at the same time as the dogs' food was served, the dogs eventually began to salivate when they heard the bell - a conditioned response. The dogs had learnt to associate the bell with being fed.

That's all well and good. If, however, a second neutral/conditioned stimulus is introduced after an association has been made between CS1 and the US, and presented consistently with CS1, then little to no association will be made between CS2 and the US. To demonstrate with a thought experiment; if I make an association between, say, eating peanuts and having an allergic reaction, then experiencing an allergic reaction after eating peanuts and drinking beer won't make me associate beer with an allergic reaction. The association between CS2 (beer) and US (allergic reaction) has been blocked.

It's simple enough, but I found the effect interesting due to the implications it raises as to how the learning process actually works in humans and other organisms.

Sunday, 19 June 2011

The BPS on the APA's DSM

So the British Psychological Society have published a response to the American Psychiatric Association's development of the DSM-5, the forthcoming edition of what is frequently (and perhaps worryingly) referred to as the "bible" of mental illness. The response is public and worth, at the very least, a quick read. Some points I found noteworthy;

On gender dysphoria;
"Of particular concern are the subjective and socially normative aspects of sexual
behaviour. We are very concerned at the inclusion of children and adolescents in
this area. There is controversy in this particular area – the concept of a ‘diagnosis’ of
a ‘psychiatric disorder’ disputed.

Labelling people who need help as ‘ill’ may make supportive and therapeutic
responses more difficult."
On neurocognitive disorders;
"We have no specific comments on these disorders, other than to say that, in our
opinion, the use of diagnostic labels has greater validity, both on theoretical and
empirical grounds in these areas."
On paraphilias;
"We believe that classifying these problems as ‘illnesses’ misses the relational
context of problems and the undeniable social causation of many such problems. ... of particular concern are the subjective and socially normative aspects of sexual behaviour. It is a matter of record that homosexuality used to be considered a symptom of illness. The Society would not be able to support considering sexual differences as symptoms of illness.

We, finally, have severe misgivings about the inclusion of “Paraphilic Coercive
Disorder” in the appendix. Rape is a crime, not a disorder. Such behaviours can, of
course, be understood, but we disagree that such a pattern of behaviour could be
considered a disorder, and we would have grave concerns that such views may offer
a spurious and unscientific defence to a rapist in a criminal trial."

Sunday, 12 June 2011

Checking In

I haven't completely forgotten about this blog, just so any readers know, and I should be giving it a redesign at some point in the near future.

While I'm here, some (very) quick thoughts on a BBS paper that hit headlines a few weeks back - Hugo Mercier and Dan Sperber's "Why do humans reason?" The vague premise of the article is that humans developed the ability to reason primarily as a method of devising and evaluating arguments in social settings.

To Mercier and Sperber, reasoning is both a primarily social phenomenon, and also a uniquely human one; they even explicitly state that "there is no evidence that [reasoning] occurs in nonhuman animals or preverbal children". This possibly counter-intuitive claim is because they make a distinction between reasoning and inferences, the latter of which are unconscious processes. They do clarify that what they're calling "reasoning" is also referred to as system 2 reasoning in dual process theories (with "inferences" being system 1 reasoning), which is language I'm considerably more comfortable with. But anyways.

There's definitely merit to their proposal (as suggested by the large proportion of respondents who are supportive of the paper, which is - as far as I know - a rarity for BBS articles), but I suspect that Mercier and Sperber are a little too quick to dismiss the alternative (or, perhaps, complimentary) hypothesis that (system 2) reasoning evolved in order to facilitate long-term planning.