Friday, March 16, 2012

Why Domain General Does Not Equal Plasticity

"It is because of, and not despite, this specificity of inherent structure that the output of computational systems is so sensitively contingent on environmental inputs. It is just this sensitive contingency to subtitles of environmental variation that make a narrow intractability of outcomes unlikely" - Tooby and Cosmides 
In my last post, I mentioned that Stanton Peele directed at evolutionary psychology the criticism of genetic determinism. For those of you who didn't read the last entry, the reason he did this is because he's stupid and seems to have issues engaging with source material. This mistake - of confusing genetic determinism with evolutionary psychology - is unnervingly common among the critics who also seem to have issues engaging with source material. The mistake itself tends to take the form of pointing out that some behavior is variable, either across time, context, or people, and then saying, "therefore, genes (or biology) can't be a causal factor in determining it". For example, if people are nice sometimes and mean at others, it can't be the genes; genes can only make people nice or mean at all times, not contingently. This means there must be something in the environment - like the culture - that makes people differ in their behavior the way they do, and the cognitive mechanisms that generate this behavior must be general-purpose. In other words, rather than resembling a Swiss Army knife - a series of tools with specified functions - the mind more closely resembles an unformed lump of clay, ready to adapt to whatever it encounters. 

                                                    Unformed clay is known for being excellent at "solving problems" by "doing useful things".

There are two claims found in this misguided criticism of evolutionary psychology. The first is that environments matter when it comes to development, behavior, or anything really, which they clearly do. This is something that's been noted clearly and repeatedly by every professional evolutionary psychologist I've come across. The second claim is that to call a trait "genetic", or to note that our genes play a role in determining behavior, implies inflexibly across environmental contexts. This second claim is, of course, nonsense. The opposite of "genetic" is not "environmental" or "flexible" for a simple reason: organisms need to be adapted to do anything, flexibly or otherwise. (Note: that does not mean everything an organism does it was adapted to do; the two propositions are quite different)

A quick example should make this point clear: consider my experiments with cats. Not many people know this about me, but I'm a big fan of the field of aviation. While up in the air, I've been known to throw cats out of the airplane. You know, for things like science and grant money. My tests have shown the following pattern of results: cats suck at flying. No matter how many times I've run the experiment - and believe me, I've run it many, many times, just to be sure - the results are always the same. How should I interpret the fact that I'm quickly running out of cats?
                                                                       Discussion: The previous results were replicated purrrrfectly.

One way would be to suggest that cats would be able to fly, were they not constrained against flight by their genes; in other words, the cat's behavior would be more "domain general" - even capable of flight - if genetics played less of a role in determining how they acted and developed. Another, more sane, route would be to suggest that cats were never adapted for flight in the first place. They can't fly because their genes contain no programs that allow for it. Maybe that example sounds silly, but it does well to demonstrate a valuable point: adaptions do not make an organism's behavior less flexible; it makes them more flexible. In fact, adaptations are what allows an organism to behave at all in the first place; organisms that are not adapted to behave in certain ways won't behave at all.

So what about domain general abilities, like learning? For the same reasons, simply chalking some behavior up to "learning" or "culture" is often an inadequate explanation by itself. Learning is not something that just happens in the same way that flight doesn't just happen; the ability to learn itself is an adaptation. It should come as no surprise then that some organisms are relatively prone to learning some things and relatively resistant to learning others. As Dawkins once noted, there are many more ways of being dead than being alive. On a similar note, there are many more ways of learning being useless or harmful than there are of learning being helpful. If an organism learns about the wrong subjects, it wastes time and energy; if an organism learns the wrong thing about the right subject, or if the organism fails to learn the right thing quickly enough, the results would often be deadly.

Cook and Mineka (1989) ran a series of experiments looking at how Rhesus monkeys acquired their fear response. The lab-raised monkeys with no prior exposure to snakes or crocodiles do not show a fear response to toy models of the two potential threats. The researchers then attempted to condition fear into these animals vicariously by showing them a video of another monkey reacting fearfully to either a snake or crocodile model. As expected, after watching the fearful reaction of another monkey, the lab-raised monkeys themselves developed a fear response to the toys. They learned quickly to be afraid when observing that fear reaction in another individual. What was particularly interesting about these studies is that the researchers tried the same thing, but substituted either a brightly-colored flower or a rabbit in place of the snake or crocodile. In these trials, the monkeys did not acquire a fear response to flowers or rabbits. In other words, the monkeys were biologically prepared to quickly learn fear to some objects (historically deadly ones), but not others.

                                 Just remember, they're more afraid of you than you are of them. Also, remember fear can make one irritable and defensive.  

The results of this study make two very important points. The first is that, as I just mentioned, learning is not a completely open-ended process. We're prepared to learn some things (like certain fears, taste aversions, or language) relatively automatically, given the proper environmental stimulation. I can't stress the word "proper" there enough. For instance, there are also some learning associations that organisms are unable to make: rats will only learn taste aversion in the presence of nausea, not light or sound, though they will readily associate shocks with light and sound.

The second point is that these results (should) put to bed the mistaken notion that biology and environment are two competing sources of explanation; they are not. Genetics do not make an organism less flexible and environments do not make them more flexible. Learning is not something to be contrasted with biology, but rather learning is biology. This is a point that is repeatedly stressed in introduction level classes on evolutionary psychology, along with every major work within the field. Anyone who is still making this error in their criticisms is demonstrating a profound lack of expertise, and should be avoided.

References: Cook, M. & Mineka, S. (1989). Observational condition of fear to fear-relevant versus fear-irrelevant stimuli in Rhesus monkeys. Journal of Abnormal Psychology, 98, 448-459.    

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