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Friday, June 1

So I had my last supervision for Evolution and Behaviour today, and seeing as how everyone likes my posts about them so much I decided to put the pedal to the metal and get as much cool information out of his as possible. This had the unfortunate side effect of me getting information overload which has resulted in me writing this up immediately after the supervision so I don't forget any of it (I took notes for the other later bits which I'll write up some other time).

What my E&B supervisor is doing for his PhD research is to look into how recognition memory works. You can test recognition memory by showing someone a set of images and then coming back a while later with a second set of images, some of them they've seen before and some which they haven't. The way in which they recognise whether they've seen one before or not is recognition memory. In a simplified way, this is what he did but when he showed them the second set of images he would ask them how confident they were, on a scale of 1 to 6, that they've seen it before with 6 being the highest level of confidence.

And what you can do is to plot curves of 'familiarity' (i.e. how familiar a particular image is) against frequency.

These curves follow a normal distribution - a 'bell curve'. In any one set of images in which each of the images have been seen an equal number of times, a person's familiarity with those images will follow a normal distribution. This means that there will be a small number of images which will be less relatively familiar than the others, a peak of 'average' familarity which most of the images have, and another tail of images which will be more relatively familiar than the others.

[to be completed later...]

/ forum / 05:04 pm GMT


Wednesday, May 30

Continuing on from the last post, we have a major unanswered question - considering that intelligence does have a genetic component to it, does this mean that our genes ultimately determine what our intelligence will be as adults? In other words, is intelligence subject to genetic determinism?

Well, first we have to understand the issues. Clearly individuals are grown based on the 'recipes' of our genes and the way in which our genes differ produce different individuals. Take height for example. We all know that there is definitely a genetic component to height; if both your parents are tall, you have a much better chance of being tall than if both your parents were short, so you could say that there are 'tall' genes and 'short' genes.

You might then assume that people with tall genes might always be taller than people with short genes. Well, you'd be assuming wrong.

Looking at the graph, let's ignore everything apart from the bottom line for the 'short' genes. What the graph is showing you is that as your diet when you were a child contains more proteins (important biochemical molecules), your height as an adult would end up taller. This also applies to people with 'tall' genes. In other words, irrespective of what your genes are, the better your diet as a child, the taller you will be.

Of course, there is a genetic component that comes into play. At any specific level of protein in the childhood diet, the short gened people will always be shorter than the tall gened people. The thing is, even a short gened person with a really good diet could end up taller than a tall gened person with a poor diet.

Before I move on, some nomenclature. The V(g) refers to the genetic variation of height in the population represented in the graph - it's the variation that exists between the shortest person and the tallest person when the environment (i.e. diet) that they are subjected to is identical. V(t) refers to the total genetic variation in height spanning all environments.

As I mentioned in my last post, heredity is V(g) divided by V(t) - it's the proportion of variation which can be attributed by genetic, not environmental, factors within a population for a specific trait.

So for height you could say that it is genetically determined, to a certain extent. Does intelligence work in the same way?

Well, a while back a group of scientists decided to find out. What they did was to take a population of rats and test how long it took each of them to solve a maze. They then took the fastest maze solvers (the 'most intelligent') and bred them together, and did the same for the slowest maze solvers. Over a period of time, they kept this up, breeding the fastest maze solvers over and over again until they came up with a really good rat maze solver. Same for the rats who were bad at maze solving. And when they were finished, they came up with these results.

On the vertical axis, we have maze solving ability, so the results that are higher on the graph represent rats that can solve the mazes quickly. On the horizontal axis we have the level of 'interestingness' of the environment that the rats were subject to when they were growing up.

The results they collected showed that at a 'normal' level of environement (i.e. they had a few toys to play with when they were growing up), one set of rats consistently outperformed the other rats at maze solving ability, and of course these were the rats which were bred for their maze solving ability.

Now the researchers were quite excited by this because they had rightly thought that they had managed to find a gene or set of genes that contributed to intelligence (or at least maze solving ability) in rats. Considering that the two sets of rats were subject to the same environment for their entire lives, it couldn't have been anything else - they only differed in their genes.

The researchers continued to gather results for this, expecting that they would follow the same sort of pattern for height. Except they didn't...

Instead of the parallel lines that we saw with height which indicated that no matter how good a short gened individuals diet was, they'd never be taller than an individual with tall genes who had the same diet, the results for maze solving ability were significantly different.

See, when the rats were subjected to a 'low', unstimulating and boring environment when they were growing up (i.e. they lived in a bare box), it didn't matter whether they had 'good' genes or not, both sets of rats performed rubbishly at maze solving ability. And when both sets of rats had 'high', stimulating and interesting environments (i.e. loads of toys and places to explore), they both were extremely good at maze solving.

This confounds the idea of genetic determinism in intelligence to quite a large amount, and it also prevents us from working out a decent value for heredity. Sure, we can figure out V(t) by measuring the difference in maze solving ability between the fastest and slowest across the entire range of environments, but the difference between the fastest and slowest at any specific level of environment changes depending on the environment. The shape of the graph isn't a parallelogram, it's an ellipsoid and as such, we can't really work on heredity.

(In other words, my 50% value for heredity of intelligence in my last post wasn't actually correct.)

This is heartening news because, if extrapolated to 'general' intelligence in humans, it means that we shouldn't worry about whether you have good genes for intelligence, we should instead worry about giving everyone the highest possible level of education and a stimulating environment when they grow up so that we can all be good at solving mazes... uh... I mean, we can all be really intelligent.

/ forum / 04:46 pm GMT


Monday, May 28

Another instalment in the 'Conversations with my Evolution and Behaviour supervisor' series:

You should all be aware that the way we measure intelligence in humans is via IQ (Intelligence Quotient) tests. When you conduct an IQ test, you don't just test for one specific thing, you test for a whole range of abilities, such as digit span, verbal reasoning and perceptual fluency, among many others. The theory goes that if you add up the results of all these various tests and take the average, you have your IQ.

If only that were the case. When I heard this, I immediately interjected and said that that couldn't possibly be right since surely these tests all test for different and not necessarily related abilities, e.g. how related is spatial reasoning and memory?

However, there is a relatively popular school of thought that says that there is one underlying basis of intelligence that all of these abilities rely upon, and it's been named the 'g factor'. Now, ignoring whether this hypothetical 'g factor' exists or not, we have to consider what the political implications of a 'g factor' would be.

Keeping in mind that the 'g factor' would essentially be the basis of intelligence, if it existed it would be so much easier for people to say that 'Well, x racial group scores lower on g factor tests than y racial group, so they must be less intelligent,' and thus possibly open the door for all sorts of nasty bias and prejudice.

If it doesn't exist, it would be much harder for people to say that because instead they'd have to claim, 'X racial group scores lower on twenty different intelligence tests than y racial group...' In other words, just having one basis of intelligence makes it easier to put people into boxes than if you have dozens of factors that contribute to intelligence.

As it happens, there isn't a single g factor that determines our intelligence. By doing a bit of nifty factor analysis on the pooled results of huge numbers of IQ tests for many different individuals and seeing how the various tests correlate with each other, it's been discovered that there are a few factors that underpin intelligence. Not dozens, but not just one. These factors 'overlap' in the areas they cover. So for example, digit span (how many numbers you can remember in one go) doesn't rely on just one of these intelligence factors but it draws on several different factors in different amounts.

Among the different underlying factors that determine intelligence is a particularly strong factor named 'gf'. The best intelligence test for deriving a 'pure' value for someone's 'gf' is an analogical reasoning test. Analogical reasoning is when you think about the relationship between two things and apply that relationship to another two unconnected things (it's a simplification, but there you go). So an example would be saying that 'a bird is to air as is a fish to the water'.

And when you think about it, analogical reasoning is a very powerful tool for intelligence in spotting similarities between different situations and applying what you know and have learnt it previous experiences to new experiences. Two excellent cases would be the way that Newton compared the falling of an apple from a tree with the way planets moved, and how Einstein conducted all his thought experiments - gedanken - like 'What happens if I'm in an elevator that's falling?' or 'What would I see if I was travelling at the speed of light?'

The question is, does intelligence have a genetic factor? Yes. Studies have shown that the heredity rate of intelligence is 50%. That means that the variation in intelligence among a population can be attributed half to genetics and half to the environment. Does this genetic factor matter, and do the genes for intelligence automatically determine how intelligent you will be when you grow up?

Well, you'll just have to wait until tomorrow to find out...

/ forum / 09:16 pm GMT


I recently downloaded the last episode of Star Trek Voyager (so you'd better look away if you don't want to read any spoilers).

I could write on for a while about what I feel was wrong with it (usual dependence of technowizardry, time-travel shenanigans and more deus ex machina that you can poke a stick at), but I think I can sum it up much more succintly: The part of the episode that will stick in my mind is the first thirty seconds, when you see Voyager flying over the Golden Gate with fireworks. Everything after that just went downhill - I'm not even sure I understood the whole bit with Voyager popping out of the Borg sphere at the end.

The thing is, it wasn't that terrible an episode and if it was, say, a season finale that would have been fine. For the end of the series though, it could have - it should have - been so much better. I guess in that respect it's a little like the ending of Star Trek: The Next Generation, which was pretty average as well, falling back on the usage of Q.

Babylon 5, on the other hand ['here we go again...'] had a fitting ending which brought the entire story to a satisfying close; it wasn't what everyone would call a happy ending, but people are agreed in that they felt it was the right ending. It didn't have huge explosions (well, it had one, but that didn't count as it wasn't in a battle) or deus ex machina. It wasn't about technology getting the heroes out of a tight situation. It was about what happens to the heroes when the journey is finished and the storytellers have moved on - about what happens after 'happily ever after'.

Oh well, at least there are a couple of promising looking science fiction shows coming out very soon; the new Star Trek series Enterprise and the new Babylon 5 series, Legend of the Rangers.

/ forum / 12:06 am GMT


 
 
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