Mind and common sense

The brain is a physical organ you could hold in your hand. The mind is not a thing you can see: you cannot see a thought, yet thoughts are real. The mind cannot exist without the brain, but it is not the same thing as the brain.

For a long time people believed only the brain affected the body. Research now shows the mind itself can change the body:

• Patients with blocked blood vessels were taught to imagine, again and again, blood flowing freely through them; over time real blood flow improved, where medicine alone had not helped.
• Psychologists use guided imagination (creative visualisation) to treat phobias.
• A whole field, psychoneuroimmunology, studies the links between the mind (psycho), the brain (neuro) and the immune system: stress can weaken your defence against illness, and a calm, positive mind can support it.

Psychology is not common sense. Everyone has ideas about why people behave as they do, but many of these ideas fail when tested.

• Common sense works by hindsight: it explains an event after it happens. For almost every saying there is an opposite one ('Absence makes the heart grow fonder' and 'Out of sight, out of mind'), and we simply pick whichever fits.
• Science must predict before the event, and its predictions can be checked.

Examples where careful study overturned popular belief:

• Many cultures once held that men are more intelligent than women. Studies found no difference in general intelligence between the sexes.
• People assume a large audience always makes performers nervous. Studies show the presence of others improves performance on tasks a person has practised well.
• Children who meet both success and failure while learning become more persistent than children who only ever meet easy successes.

So psychologists, unlike astrologers or fortune-tellers, base claims on evidence, test them, and change them when the evidence disagrees.