Jul 01 2010

Subconscious Motivation

Neuroscience research has been increasingly fleshing out the fascinating and complex relationship between the subconscious processing of the brain and our conscious awareness. We all labor under the illusion that our decisions, feelings, and behaviors are all conscious. When we do something, it seems, it is because we wanted to do it. We are very good, in fact, at retrofitting a logical explanation for why we consciously did something.

But much of our brain’s decision making occurs at a subconscious level. When presented with a choice various parts of our brains make a calculation – processing the choice, weighing varying factors based upon some neuro-algorithm, and then present that choice to our conscious mind (the global workspace, if you accept this hypothesis). Research shows that if we change the subconscious algorithm, by suppressing, for example, one part of the brain, the decision-making process is altered. We are not aware of this, and we still are under the illusion that the decision was completely conscious.

Added to this is increasing evidence for information processing in the brain of people who appear to be in a persistent vegetative, or perhaps minimally conscious, state. They give no evidence of conscious awareness, but fMRIs will show that their brains are responding to environmental stimuli in complex ways. This research is still preliminary, but perhaps the subconscious processing is still there – there is just no consciousness to present decisions to.

When I discuss this topic with people, while fascinated, many people will recoil a bit from the implications of this research. It makes us sound more like automatons than moral agents. This is not strictly true – we still have hierarchical conscious control over our behavior. In fact, awareness of how our brains work might give us more control because we won’t assume that our “default” decisions are completely our own conscious choices. Realization of how our brains work should motivate us to step back and consider our more important decisions more deeply, and not just rationalize what we feel. But still – the implications of this research seem strange.

However, what really brings the reality of this research home are the more bizarre sets of experiments that clearly show the subconscious processing of the brain – specifically, split brain research. This involves separating information given to each half of the brain and then demonstrating that each hemisphere is, to a degree, making its own decisions. This is most dramatic when performed on patients who have had their hemispheres separated by cutting the corpus callosum. You can show their right hemisphere a bottle of soda. They cannot say what they are looking at, because only their left hemisphere can speak. But when given a choice, they will reach for the soda, and not be aware that they are doing so because their silent half of the brain was just looking at it. So they will make up a reason – they were thirsty.

Now new research (on neurologically intact individuals) shows that the different hemispheres can have differing amounts of motivation – meaning that motivation itself is at least partly subconscious. Mathias Pessiglione, of the Brain & Spine Institute in Paris, and colleagues did a split-brain study where they had subjects look at a cross in the middle of a computer screen. Then pictures of coins (a penny or a euro) were shown in either the left or right visual fields – but only for a fraction of a second – enough for subconscious processing but not conscious awareness (so-called subliminal processing). They then asked the subjects to squeeze a handle that would measure their strength and would told they would be given a reward (not specified).

When the right hemisphere was shown the euro, the subjects squeezed harder with their left hand (the right hemisphere controls the left hand) than when shown the penny. This did not occur when theĀ  opposite hemisphere was shown the larger reward.

This means that motivation can be influenced by just one hemisphere and by subconscious information. Therefore motivation is not entirely a conscious phenomenon.

While this is just one study, it extends the research showing the relationship between our conscious and subconscious brains, and increases the apparent role of subconscious processing.

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