The Master and His Emissary: The Divided Brain and the Making of the Western World

by Iain McGilchrist

To sum up, the right hemisphere is responsible for every type of attention except focussed attention. Even where there is divided attention, and both hemispheres appear to be involved, it seems probable that the right hemisphere plays the primary role

When patients who have had a right-hemisphere stroke are offered constructive guidance about their performance it makes little impact.453 In the words of one researcher into head injury, ‘children with right-brain deficit disorder ignore task obstacles, accept impossible challenges, make grossly inadequate efforts, and are stunned by the poor outcomes. These children act fearless because they overlook the dangers inherent in the situation.’454 A highly intelligent professional described by Stuss was completely unaware of his lack of capacity to do his job after the removal of a tumour in the right prefrontal cortex. When asked to role-play as an occupational health adviser to someone with his problems, he appropriately advised medical retirement, but when asked to apply this insight to his own situation he was completely unable to do so.455

Insight into illness generally is dependent on the right hemisphere, and those who have damage to the right hemisphere tend to deny their illness – the well-recognised, and extraordinary phenomenon of anosognosia, in which patients deny or radically minimise the fact that they have, for example, a blatant loss of use of what may be one entire half of the body.461 A patient with a completely paralysed (left) limb may pointedly refuse to accept that there is anything wrong with it, and will come up with the most preposterous explanations for why he is not actually able to move it on request.

Hoff and Pötzl describe a patient who demonstrates this beautifully: ‘On examination, when she is shown her left hand in the right visual field, she looks away and says ‘I don’t see it.’ She spontaneously hides her left hand under the bedclothes or puts it behind her back. She never looks to the left, even when called from that side.’

Denial is a left-hemisphere speciality: in states of relative right-hemisphere inactivation, in which there is therefore a bias toward the left hemisphere, subjects tend to evaluate themselves optimistically, view pictures more positively, and are more apt to stick to their existing point of view.467 In the presence of a right-hemisphere stroke, the left hemisphere is ‘crippled by naively optimistic forecasting of outcomes’.468 It is always a winner: winning is associated with activation of the left amygdala, losing with right amygdala activation.469

Sadness and empathy are highly correlated: this can be seen in studies of children and adolescents.470 There is also a direct correlation between sadness and empathy, on the one hand, and feelings of guilt, shame and responsibility, on the other.471 Psychopaths, who have no sense of guilt, shame or responsibility, have deficits in the right frontal lobe, particularly the right ventromedial and orbitofrontal cortex.472

The right frontal lobe’s capacity to inhibit our natural impulse to selfishness means that it is also the area on which we most rely for self-control and the power to resist temptation.

cocaine addicts, for example, stimulating the right prefrontal cortex reduces craving for cocaine.485 And denial, a left-hemisphere speciality, is typical of addiction.

I believe the essential difference between the right hemisphere and the left hemisphere is that the right hemisphere pays attention to the Other, whatever it is that exists apart from ourselves, with which it sees itself in profound relation. It is deeply attracted to, and given life by, the relationship, the betweenness, that exists with this Other. By contrast, the left hemisphere pays attention to the virtual world that it has created, which is self-consistent, but self-contained, ultimately disconnected from the Other, making it powerful, but ultimately only able to operate on, and to know, itself.

We need the ability to make fine discriminations, and to use reason appropriately. But these contributions need to be made in the service of something else, that only the right hemisphere can bring. Alone they are destructive. And right now they may be bringing us close to forfeiting the civilisation they helped to create.