Reading Minds

Reading minds

In a wonderful bookTHE “ NEW BRAIN”, the author, Dr Richard Restak, writes on understanding human subjectivity on a scientiﬁc basis.

“Most of us at least occasionally act in illogical or irrational ways. Although we know what we should do, we do just the opposite. Can brain research provide any help here? Yes, according to psychologists William Gehring and Adrian Willoughby at the University of Michigan. In their experimental study published in the journal Science, volunteers donned electrode caps that recorded event-related brain potentials (ERPs). ERPs, like MERMERs, are changes in brain electrical activity in response to a speciﬁc stimulus.

Gehring and Willoughby measured ERPs while their subjects engaged in a betting game played on the screen of a computer. Two boxes were displayed – one box represented a 5-cent bet; the other a 25-cent bet. After the subjects made a selection, the boxes changed colour. If the box selected by the gambler turned green, the amount in that box was added to the player's winnings; if it turned red, the amount was subtracted from the winnings. A few seconds later, after the screen reconﬁgured the boxes, the subjects chose again.

Win or lose, the subjects' brain waves displayed greater activity (signalled by a downward dip in the brain wave recording) from the medial frontal cortex. But this medial frontal negativity (MFN) showed the greatest dip after losses – a response that occurred within 200 to 300 milliseconds (about a quarter of a second) after the gambler learned the outcome of each bet. During a string of losses, the MFN dipped further with each subsequent loss.

Gehring and Willoughby suggest this increased MFN activity corresponds to the well-known gambler's fallacy: that consecutive losses mean a gambler is 'overdue' for a win, which fuels escalations in the amount of money bet. In other words, there is a correlation between the gambler's tendency to bet more following a string of losses and the degree of dip that occurs in his or her brain's MFN.

'Losses loom larger than gains,' write Gehring and Willoughby. 'The aversion to a loss of a certain magnitude is greater than the attraction to a gain of the same magnitude. After a loss the brain thinks it's due for a win. As a result, when we make a quick decision and it turns out to be wrong, we tend to take a bigger risk the next time than we would have if our ﬁrst choice was right, and we can evaluate the outcomes of these decisions before we've consciously thought about what we're doing.'

Freud wrote about unconscious mental processing that some-times led to decisions made without recourse to conscious deliberation. But Freud tethered his observations to controversial and debatable theories about the importance of underlying aggression and sexuality. Now neuroscience is revealing, instead, that unconscious mental decisions, like the gambler's fallacy, result from a rapid quarter-of-a-second computation. Further, these split-second, often impulsive decisions about how well things are going are linked to a distinct pattern of activity

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(MFN) carried out by the ACC.

The MFN study represents an early step towards understanding human subjectivity within a neuroscientiﬁc basis. Further developments will depend on designing experiments that combine behavioural observations with recordings of the electrical events within the brain. As with the Gehring and Willoughby study, we may ﬁnd that the electrical events take place in fractions of a second – far too quickly for anything approaching conscious deliberation.

For example, imagine yourself rapidly scanning a series of pictures of human faces. As you look at some of the pictures, a loud burst of unpleasant noise plays in the background. Not surprisingly, your brain responds to the noise with mild fear. But after a while your brain becomes conditioned and automatically responds with fear when certain faces are shown, those paired with the unpleasant noise.

But suppose the pictures are shown so rapidly that you don't consciously perceive them. Shouldn't that eliminate the mild fear response? Actually, while some parts of your brain will respond less or not at all, the response from the amygdala will be the same whether or not you are consciously aware of the pictures. It's as if the conditioning process sets the amygdala at a higher sensitivity.

A similar response occurs in survivors of horriﬁc events such as the September 11 attacks. 'When you scan them, you discover that their amygdalas are switched on to far higher levels than you would ﬁnd in the average person,' says Rashid Shaikh of the New York Academy of Sciences.

In short, functional neuroimaging is providing us with new ways of looking at how our emotions are programmed within our brains. Thanks to fMRI and other techniques, the nerve cell networks responsible for our emotions are being mapped out, most notably within the circuitry of the amygdala and anterior cingulate cortex. This imaging of thought and emotion has practical implications for how we reach everyday decisions.

'Emotional and rational parts of the brain may be more closely intertwined than previously thought,' says Dean Shibata, assistant professor of radiology at the University of Washington. In his research, Shibata scans the brains of subjects while they are in the process of making decisions. He finds that it makes a good deal of difference in the brain whether the decisions involve choices that affect health or well-being – decisions such as, Should I put on a seat belt? Should I make an appointment for a medical check-up?

'Our imaging research supports the idea that every time you have to make choices in your personal life, you need to “feel” the projected emotional outcome of each choice – subconsciously or intuitively,' says Shibata. 'That feeling guides you and gives you a motivation to make the best choice, often in a split second.'

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Shibata finds that making decisions that affect you personally enhances activity in part of your frontal lobes (the ventromedial frontal lobe). As a rule, you do not activate that area when thinking about events that do not involve you personally. 'When people make decisions that affect their own lives, they will utilize emotional parts of the brain, even though the task itself may not seem emotional,' says Shibata.”