All of us are good at some things and poor at others. Some people are good at remembering people’s faces but can never remember their names. Others are good at art, useless at spelling. Most psychological functions come from specific brain areas and if these areas are damaged, then you may lose some particular ability.
Epileptic seizures often arise from a small area of damaged brain. By assessing someone’s different mental skills it is often possible to see which part of the brain may have been damaged. This is done by psychometric testing.
Essentially, psychometric testing involves answering a lot of questions which have been designed to test the functioning of different brain areas. In some you will be asked to write down the answers, in others you will have to give a verbal answer or perform some simple task. All these tests have to be given in a very specialized standard way by a trained neuropsychologist who knows not only how to give them but also how to interpret the results. Sometimes an abnormality of brain functioning can be detected in this way even though nothing has shown up in the EEG or CT scan, and more and more epilepsy units now realize the value of having a trained neuropsychologist as a member of their team. If you are to have psychometric testing, it is important to let the psychologist know if you have had a seizure in the day or so before the tests as this may alter the results.
Doing the tests
The psychologist will sit down opposite you at a table in a quiet room so that you can concentrate on the tests. Usually the first set of tests will assess your general level of intelligence, and also show whether both left and right sides of your brain are working equally well. Some of these tests are mainly verbal, and include vocabulary tests, questions which test your understanding of different situations, and arithmetic tests. In right-handed people these test the functioning of the left side of the brain. Others are to do with your perception of space; they may include tests asking you to analyse the meaning of pictures, cancel out symbols, and put blocks into spatial patterns. They test the functioning of the right side of the brain. These two sets of tests will each be scored, to give two IQ scores, a verbal IQ and a performance (spatial) IQ. In most people these two figures are nearly the same. But if one half of the brain is damaged, then there will be a discrepancy between the two scores.
You will then be asked to do other tests to measure special brain functions. Memory, for example, is situated in a special part of the temporal lobe, the hippocampus. Memory for words is on the left side, and memory for pictures on the right. If there is any damage to the hippocampus on either side of the brain, one of your memory scores will probably be lower than the other.
Damage in other regions of the brain can be tested for in the same way. Your ability to recognize faces, for example, is at the back of the right temporal lobe. Verbal fluency tests (measured by counting the number of words beginning with a given letter that you can say in 5 minutes) will test the left frontal region whereas spatial sequencing tests (such as working your way through a maze) will test the right frontal region. You will not have to do every available test; the psychologist will know from the results of your EEG and brain scanning which area of your brain is likely to be damaged, and the questions you will be asked will be to test the functioning of this particular area.
Do not worry if you fail on the tests. In fact, the tests are graded so that they start easy and then become harder as you go through them, so that at some point you are almost bound to fail. This does not matter. They have to be designed so that no one will find the whole test too easy, however clever they are. The aim is not to see whether you pass or fail, but only to find out whether some parts of your brain are working less efficiently than others.
A neuropsychological session will usually take one to two hours and you will find it quite tiring (but usually quite fun as well) as you have to concentrate for all this time. Sometimes it may not be possible to complete all the tests in one session, and in this case you will be asked to come back another day to finish them.