Tuesday, January 23, 2007

N400 and the beautiful is good stereotype continued, results from my current research

In a previous post I described my current research in which I tried to measure the beautiful is good stereotype using EEG. The idea is that when we are presented with something that contradicts our stereotypes, our brain says "wait a minute, those just don't go together, that is odd". It just so happens that there is an ERP component, called the N400, which is sensitive to mismatching stimuli.

So in my experiment, participants were presented with faces rated as either attractive or unattractive, followed by words rated as either positive or negative. Their EEG (their brain activity), was measured throughout the experiment. We expected to find that the magnitude of the N400 wave/component would be larger when presenting incongruous face-word pairs. Pairs that are incongruous contradict the stereotype, so in this experiment it would be attractive faces followed by negative words or unattractive faces followed by positive words.

So what did we find? Do our brains object when they see an attractive person followed by a negative trait or when an unattractive face is followed by a positive trait. In our experiment we found no N400 for attractive faces, however, we did find a clear effect for the unattractive faces. This supports the view that rather than having a "beautiful is good" stereotype we have an "ugly is bad" stereotype. Just to spell it out, our data showed that when the average participant was presented with an unattractive face followed by a positive word, the brain responded with a larger N400 component, indicating that there was a mismatch between the two stimuli, they did not go together. According to our data, it is much harder to imagine an unattractive person with positive traits than an attractive person with negative traits...

Another discovery that we made during the study is that there was a difference in the EEG that depended only on the type of face presented, that is the EEG activity following presentation of an attractive face is different from the EEG activity that follows the presentation of an unattractive face. Interestingly, the difference in EEG activity following presentation of either attractive or unattractive faces is highly similar to the difference that you see when you present pleasant or unpleasant stimuli. So it would seem that perceiving an attractive face will "reward" your brain. This is also supported by fMRI studies in which it has been shown that perception of attractive faces leads to activity in parts of our brain normally associated with reward.

If you are still curious and want a more complete description of the experiment you can download the entire article here.

The next step in our research is to investigate further what types of positive traits are associated with attractive and unattractive faces. A previous meta-analysis have shown that we associated attractiveness more with social competence than with intellectual competence. We are going to see whether this pattern we will also see this pattern when we measure the stereotype using N400. Furthermore, we are going to see if there is a link to memory. One could speculate that it is easier to remember face-word pairs that agree with our stereotype because we already have a developed network to store such information (or something like that). Or, alternatively, perhaps we remember incongruous information better because when we see something that does not agree with our stereotype we use lots of resources to reconcile it with what we know, and since the level of processing of a stimuli is correlated with how well we remember it, it is possible that we will remember incongruous pairs better. We will see...

Sunday, January 21, 2007

The difference between science, faith and religion

I am sure everyone who have been reading this blog occasionally will know by now that I am a science freak. I think that science is the way to gain knowledge. Many people say that science is narrow minded, that believing in science will confine the scope of our knowledge, but I disagree. Science, for me, is an open minded and modest approach when it comes to discover new things. Science is based on evidence. However, evidence is not necessarily gathered in a laboratory by people in white lab coats, evidence can be all sorts of things. As defined by oxford concise dictionary, evidence is "the available facts, circumstances, etc. supporting or otherwise a belief, proposition, etc., or indicating whether or not a thing is true or valid".

So what does not count as evidence you might wonder. My own answer to this, which I have not thought so much about, is things that can just as well be explained by chance. Often, when I discuss homeopathic medicine or other alternative approaches to medicine, I hear statements such as "well look, person x got well after taking this medicine, you see, it works". Perhaps this could be seen as evidence, but if so, it is one of weakest forms of evidence. Why? Because person x could have gotten well for any number of reasons, after all our immune system will deal with almost everything in a relatively short amount of time. I would take any type of medicine seriously, including homeopathy, if they could show in a double blind experiment that it worked.

Science is not the same as faith which is defined in my dictionary as "complete trust or confidence", or "firm belief, esp. without logical proof". As I have just shown it is almost the opposite. My ideal is to be sceptical to ideas with weak evidence, but not so sceptical that I cannot be convinced when proper evidence does exist.

Science is also different from religion which in my dictionary is defined as "the belief in a superhuman controlling power, esp. in a personal God or gods entitled to obedience and worship". Science is a method (or rather a gizillion methods) to achieve knowledge. Religion, on the other hand, is a belief in a superhuman nature, they are completely different concepts. A minority of scientists are religious (Einstein, by the way, is not one of them), the majority is not. The two are in other words more or less independent of each other. This is not entirely true of course since by scientific standards, religion is a weak theory with a minimal amount of supporting evidence. For this reason I am an atheist, but again, if proper evidence is shown to me I would change my mind.

I want to end with a great quote by Carl Sagan that I just read and which captures most of what I have written here; "Be open-minded, but not so open-minded that your brains fall out."

Tuesday, January 16, 2007

Get smart! Two great resources for people with "learning hunger"

Except for a weak period that I had during my teens I have always been a very curious person who loves learning. However, never before have I learned at a rate that is comparable to my current learning pace. What is this all about? I will tell you!

About two months ago I discovered two fantastic knowledge resources and since then I have been listening or watching lectures when I am on the bus, taking a walk, doing the dishes, cooking, running, playing soccer etc (OK, that last one was not true, but its close). I really really recommend both of these websites to anyone who likes to learn things.

The two sources are:
1. Berkeley webcast
2. The Teaching Company

The first one is University of California, Berkeley's webcast (see picture). Here you can watch or listen to lectures in many different field ranging from biology, physics and chemistry, to philosophy economics and non-violence. I am currently watching "physics for future presidents", which is a great great great (I don´t know how else to describe it) lecture series by professor Robert Muller. He goes through pretty much all of physics in a very interesting and intriguing way. One guy commented on Google video that "I would listen to this guy (Robert Muller) even if he had his pants down while talking". I have also been watching introduction to chemistry to try to really understand quantum mechanics, which is still difficult though...

The second resource is perhaps even better. The teaching company hand picks the best professors in the world and asks them to make a series of lectures in their field of expertise. You can order the lecture from their website, or if you are the hacker type the courses are sometimes available for download. The quality is consistently top class. I have already taken 24 or 36 lecture courses in the following fields.

(1) Neurobiology of behavior, by Robert Sapolsky at Stanford University
(2) Introduction to economics, by Timothy Taylor at Macalester College (this guy actually made me realize that economics can be interesting)
(3) Argumentation, by David Zarefsky at Northwestern University
(4) History of Russia, by Mark Steinberg at University of Illinois
(5) Understanding the Human Body, by Anthony Goodman at Montana State University (he used to be the general surgeon)

As the teaching company says in the introduction to their courses "Imagine how much you could learn if you spent 30min everyday in the best classrooms in the world".

Thursday, January 11, 2007

Evolution is NOT blind chance

At one point in Woody Allen´s excellent movie Match Point, the main characters, all coming from the British upper class, are having a conversation about the meaning of life. Chris Wilton (see picture) played by Jonathan Rhys Meyers, comments that scientists are becoming more and more certain that there is no meaning to life, that we are all here by blind chance (after which the other in the company desperately tries to change the subject. I do not know whether this is what Woody Allen believes, a fast google search suggested that he was an atheist so maybe he is just having Chris say this because it is something people often think. In any case, this is something you hear again and again, and it is quite tedious to be frank. It is also a cause of concern if you ask me. If people hear that evolution is the same as blind chance when they go to the cinema, have a chat at the pub or turn on the telly, then they might start to believe that it is in fact so, even though it is not.

(Warning, spoilers in this paragraph!!!)
I do not know if it is a coincidence that it is the same Chris Wilton who later in the movie commits adultery, makes his lover (played by Scarlet Johansson) pregnant because of carelessness, and then kills her, her neighbour (to make it look like a drug related crime), as well as his own child that is growing inside his lover. I am personally inclined to believe that Woody Allen is well aware of this "coincidence" considering the many references made to Dostoevsky. Dostoevsky thought that without a religion and a God who punish bad behavior and rewards virtuous behavior, we would all be savages.

I had a similar experience one late evening about two years ago when I was visiting my father on Jamaica. I was zapping around on the telly to see if I could find anything interesting to watch. I finally stumbled upon a program in which a scientist would, in a very intriguing way, describe the amazing feats performed by many animals. Most vividly I remember his description of a lizard. He showed how, on a microscopic level, this lizard had almost perfect machinery for walking in the roof. In the end he asked, "do you really believe that this lizard came about through pure chance?". He went on to say, "of course not, it is obvious that it has been designed to do what is does". Since I liked his descriptions of the animals I was actually quite saddened when I learned that he had bought into the idea that evolution is the same as blind chance.

Considering that it such a widespread and often articulated myth, it is perhaps not so strange that people believe that evolution and blind chance are synonymous. To me the fact that evolution is not the same as blind chance, complete randomness, accident etc is extremely obvious. Random mutations change the phenotype of the individual with the mutation. This change in the phenotype can increase the chance of the individual surviving, it may decrease the chance of the individual surviving, or it may have no effect on survival. When the mutation affects the chance of survival (or more accurately, the chance of copying genes into the next generation), natural selection will either favour that mutation, or work against it.

To illustrate, imagine a hypothetical population of rabbits. On average they get the same number of offspring, and they are equally likely to be eaten by whatever animals eat rabbits (is it foxes??). However, one day, two happy rabbit parents give birth to a rabbit baby with a mutation in a gene that affects the sensitivity of the retina. This new baby rabbit, as a result of its improved retina is ten percent more likely to discover a predator in time and therefore avoid being consumed. When this baby rabbit (unless he or she is eaten) becomes a proud parent one day, the offspring inherits the improved retina and therefore the higher chance of survival in encounters with predators. How long would it take for a mutation that increased the survival chance by 10% to spread throughout the whole population? Is it one thousand generations, or a million perhaps? No, if you do the math in this hypothetical example a more plausible estimation would be around 15 generation. At that point, due to the better survival chance of individuals with the mutation, all rabbits will have the new retina. That is how natural selection works. EVOLUTION IS NOT THE SAME AS BLIND CHANCE!