Tuesday, 31 May 2011

Stories from childhood

At 11 years old I changed school to one with separate lessons with specialist teachers.  My biology teacher introduced us to the theory of evolution in the first lesson.

It made complete sense to me - if there is a subset of a species with a mutation (adaptation) that makes them ever so slightly more likely to have [more] kids then, over a long time in a large group, those mutations will become increasingly common (because they are genetic) and thus the species evolves.  Conversely, any trait that makes it less likely for an animal to reproduce (such as causing them to die quickly) will be strongly selected against.

I came home from school that day and said to my mother, who was a high-school biology teacher herself, "why do people believe that ostriches stick their heads in the sand when they see a predator?"
"Because they do"
"But if they did they would die out very quickly - that's evolution, and it's obviously true whereas 'common knowledge' is sometimes wrong"
"Well it's not wrong in this case"

This incident greatly influenced how I thought of my mother from then on.

Monday, 23 May 2011


I read an article based on a paper recently that concluded you could tell if someone were criminal from how they look.  I was astounded at the bad science behind it - there was no attempt to mitigate for, or even mention, the possibility that it was hairstyle or someone generally looking like they have had a hard life that provided the (somewhat weak) correlation with criminality.  Personally I don't think this study can conclude anything - in which case why did they bother?

As an aside - there is evidence that better looks are correlated with higher IQ.  I know it is with me anyway ;)

The weakest correlation was with rapists - suggesting (to me) that men from all walks of life can be capable of rape, whereas someone who is in a gang, or trailer park, etc, is much more likely to commit and be caught for murder than some white collar dude.

Anyway, here are some of the pics used in the research.  I'll post the answers and link the paper in a few days' time to give you a chance to see how you do!

Who are the criminals? 

Tuesday, 17 May 2011


In the NY Times a couple of days ago, there was an article written by an economist explaining why people sometime make bad decisions.  He obviously understands that evolutionary pressures have shaped our minds - shaped them to survive long enough to pass their genes on to the next generation, not shaped them to be happy.  He posits that happiness is usually only fleeting, and its allure is held in front of the mind like a carrot; he suggests that our minds are wired to be anxious and unhappy as the prime motivating factor in people's lives.

There is a lot wrong with his article, but the things it got right got me thinking.  I agree that happiness for most people lasts a much shorter time than being anxious or unhappy, and I know that most people instinctively move towards carrots and away from sticks.  Most people.  What about those who aren't neuro-typical?  People with flat affect, a smaller than average amygdala, a low fear response, have been shown conclusively to not react (not nearly as much anyway) to metaphorical sticks.  It is no use using punishment as a means of changing the behaviour of someone with an antisocial personality disorder - there has to be a carrot dangling somewhere.  Those with BPD and other disorders associated with anxiety do experience the stick, but it is beating them in every direction depending on which way the wind is blowing.

So is the reason that those with flat affect, and those who are overanxious, have difficulty with long term objectives simply that the motivation is too low or the direction the motivation is never in the same direction for more than 5 minutes?

Saturday, 14 May 2011

The Eyes

The eyes are the window to the soul, so they say. 
A massive part of our brain is dedicated to the visual analysis of our world, which is probably why we feel that the centre of our being is in our head – I think this feeling is more related to the location of our most important sense than to the actual location of our brain.  A hippy friend once said to me after he'd bumped his head on a short doorframe, "I always forget I have a body above my eyes".  he was stoned at the time though.

The reason we need a lot of brainspace for our vision is that it is a very complex mathematical problem to solve. 
If you have only one eye then it is presented with a 2D image with no depth information – your depth perception is certainly much reduced with only one eye, but you can navigate your way around day to day life without difficulty. 
This is something that is not to be sniffed at – your brain has to make many many assumptions about what an object's shape actually is and some shading information to then turn this into a sensible image presented to your conscious mind. For example, you know a TV screen is a rectangle, but if you see it from an angle it will form an image of a parallelogram onto your retina. It seems reasonable to assume it should actually be a rectangle and therefore is interpreted as a rectangle at an angle. What if it isn't an object you've seen before... a lot of processing is needed and optical illusions show some of the limitations of that processing.

When you have 2 eyes depth perception becomes easier, because each eye sees a slightly different image due to parallax. However, turning these 2 images into a coherent 3D world is nothing to be sneezed at either, and even the very best computer systems with artificial vision (2 camera 'eyes') are very slow and have a high failure rate compared to a human being.

The computational theory of mind is still the best theory to explain how we do things, and the current limitations on artificial vision are not evidence against it, but merely highlight what a massively complex calculation it is, and that it does require some reasonable assumptions – vision is an incomplete information problem.
One interesting validation of the computational theory of mind to do with vision that I read about recently concerned the reaction times of recognising shapes. Someone is asked to memorise a list of a few strange symbols, and then shapes are flashed onto a screen. When one of the ones in the list appears the subject presses a button. If the shapes are rotated when they are flashed up then the time it takes to recognise it is linearly proportional to the angle it was rotated by. This seems reasonable if the brain has a 'module' that rotates shapes. If the shape is a mirror image and rotated then the reaction time is exactly the same no matter what the rotation. At first this puzzled the researchers but a mathematician pointed out to them that for a rotated mirror image there is always a single axis to flip it about to get it back to the original image – all the shapes only required one flip in the mind's eye. How it determines where this axis is was not explained...

So in conclusion, the world you see is not the actual world – it is blemish corrected, your blind spot (where the optic nerve comes out of the retina) is filled in with guesswork, and is heavily image processed. Our heavy reliance on vision has shaped our thoughts and metaphors in our language.

And yes, that is my eye.

Thursday, 5 May 2011

Sphex Wasp

Sphex wasps, when they reproduce, paralyse prey and lay their eggs in/on it.  When the eggs hatch the baby wasps have a fresh food source to give them a good start in life.

The mummy wasp digs a hole in the ground (they are commonly known as digger wasps) then goes off and brings back a paralysed grub.  It sets it beside the entrance to the hole and goes into the nest.  It is possible that another wasp has commandeered the hole.  After a quick look around it comes back out and grabs the grub, drags it into the hole, lays its eggs, and leaves (covering the hole entrance).

This seems like reasonable and intelligently foreplanned behaviour.

If, when the wasp goes into the hole, you move the paralysed grub by an inch or two, it comes out, re-locates the grub, moves it back to beside the hole entrance, and then goes back inside the hole.  It looks around then comes out again.  If you have again moved the grub, and continue to do so, the wasp will be caught in an infinite loop of hardwired behaviour.

Are you?