A matter of choice (Australian Doctor, 8 October 2010)

October 8, 2010 § Leave a comment

EARLIER today, I needed to buy a stapler. It took longer than expected because the shelves contained dozens of alternatives. There was too much choice.

Our mixed communities even give us a choice of religion. A favourite homeless patient once told me that if you are going to have an imaginary friend, you may as well have lots of them. He chose a polytheistic Eastern religion because he needed all the friends he could get.

Another of my favourite patients is a vegan, a choice he made decades ago. Last month, I broke bad news to him. He had been getting headaches and a CT scan showed brain cancer. My patient — a thinker and one-time associate of Bertrand Russell — remains disappointed. His brain is important to him.

My father felt the same way about his own brain. The same news created similar disappointment. To my surprise, my mother’s initial reaction was more complex. Apparently multiple cerebral secondaries did at least explain some recent behaviour changes. I believe my mother just meant that my normally kind and placid father had become an unpredictable grump — but occasionally more dramatic behaviour changes make the news.

In a well-publicised case, a paedophile had a brain scan the day before sentencing. A frontal lobe tumour was discovered and its resection cured his aberrant behaviour. When the tumour recurred he relapsed.

It seems common for us to behave as if smoking, eating junk food and, of course, poverty are all choices. In some situations, however, it seems paedophilia is not.

The neuroscience of choice is surprisingly little-known … or perhaps not surprisingly little-known. Life is difficult enough without trying to deal with reality.

Libet’s classic neurological experiments on choice were conducted decades ago. These showed a pretty obvious result. If people decide to move their wrists then, a fraction of a second later, their wrists will move.

The freaky bit was that the brain’s motor centres causing the movement would spike on an EEG about half a second before the conscious decision was made to move. This finding has been reproduced many times and it seems that the requisite motor cogwheels are in motion before we make the apparently free choice that NOW is the time we want to use them.

More recent experiments further suggest that conscious choices describe actions but do not control them. For instance, in one study, participants were asked to freely decide whether they wanted to press a button with their left or right hand. High-tech brain scanners could then accurately predict, many seconds before any conscious decision was made, which hand subjects would choose.

These research findings are more or less supportive of what Western philosophers term epiphenomenalism. Lay people usually term it bollocks because it is bizarre to think conscious decisions do not impact on behaviour.

Smarter people than me are busily constructing Ptolemy’s epicycles to explain away the research. And I’m sorry if you didn’t enjoy this article but it had to be written. I had no choice.

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