Consciousness is a byproduct

Intuitively most people think that what we do is mediated by our consciousness. In other words, when I decide to raise my arm it is because I made some sort of conscious choice in my brain which then resulted in signals going down my corticospinal motor pathway and out to the muscles in my arm. 

I think that this is wrong. What is going on rahter, is that after the signal telling my muscles to contract have left my brain, then we become aware that this is the case. In other words being aware of what you do is merely a sort of byproduct, or epiphenomenon if you want to use a more academic language.

What is the evidence for this you might ask and I may answer what evidence do you have to support that our conscience can move an arm? However, I can do better than that because it turns out that there is indeed experimental evidence, produced by Benjamin Libet, suggesting that our consciousness is a byproduct. Benjamin Libet's subject were asked to do a very simple motor task, namely flex their index finger, they could to this whenever they wanted to. Libet wanted to measure the timing of three things, first when the muscle activity in the finger started, he did this using EMG electrodes which has high precision. The second variable he wanted to measure was when the brain activity leading to the action started, this was done using EEG scalp electrodes which like EMG has high temporal precision in the millisecond range. The third and perhaps most crucial variable Libet wanted to measure was when the conscious intention to flex the finger came. To do this he had a type of clock in which one arm would go a full revolution in 2,5 seconds. His subjects were told to report where the arm on this clock was when they first intended flex their finger. 

One would expect that if indeed we first intend to do something and then do it (which is a very intuitive scenario I will admit), if this is so then the flexing of the finger should occur subsequent to when the subject reported their intention. However, this was not the case, rather the flexing of the finger occured quite a while (approximately 500 milliseconds) before the conscious intention. The conclusion from this is that the brain knows that it is going to do something before the person does, or to be more precise, the part of the brain that handles motor initiation first do its thing, then after that the information is given to the part of the brain that mediates conscious awareness.

Many people when they hear this draw very radical conclusions, such as, why should we punish people if they do not have free will, or why should I care about anything, or do anything, what prevents me from becoming a nihilist. I one thinks about it, these conclusions are (at least in my opinion), unwarrented, but nevertheless interesting. I have touched upon these subjects before Perhaps they will be the topic of a later post...

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...

My current research project (fall 06) - Electrophysiology and stereotypes...

Since I am doing the "C-course" in psychology at Lund University, I am expected to carry out a research project. I was lucky to be allowed to use the rather new EEG lab that has been set up. This allowed me to do an experiment that I have been thinking about since the spring but which I have not had the chance to do until now

So what is my project about? I am actually trying to do something as sexy as measuring peoples' stereotypes using EEG. An EEG (see picture) measures the electrical activity that the brain generates. This electrical activity differs depending on what the brain is doing. If you are sleepy the brain will start to generate what is referred to as alpha waves (a funny consequence of this is that you can actually see when your subjects are starting to get fed up with your experiment), if you are dead there will be a straight line, an epileptic seizure is characterized by wild activity etc etc. In fact, the brain also generates characteristic wave patterns in response to certain events, these patterns are called event-related potentials or ERPs.

In my experiment I am looking at a specific wave called the N400, N because it is a negative deflection, and 400 because it occurs 400 milliseconds after the stimuli was presented. The N400 appears when our brain perceives something unexpected. For example, when the brain hears a sentence such as "Jack took the bus to town to meet some of his boxershorts", the brain says, wrooong!! (an N400 wave appears). Similarly, if famous faces from different occupations e.g. Robert De Niro and Billy the clown, are presented serially, the N400 also appears, thus suggesting that our brain has recognized that these two stimuli did not belong to the same category.

I am reasoning that stereotype incongruency, that is, things that go against your stereotype, will also elicit this N400 component. To test this prediction I have obtained a collection of attractive and unattractive faces as well as a collection of negative and positive words. Presumably the N400 component will appear when I present to my participants an attractive face followed by a negative word, or conversely an unattracitve face followed by a positive word. The reason I believe so is that there is a lot of evidence suggesting that we associate attractive faces with positive characteristics and unattractive faces with negative characteristics. To be continued...