There is a growing concern amongst some psychologists working on ageing. It is that the way tests are administered may impact the results. The findings are used to draw inferences about the way age effects cognitive ability. As a result they run the risk of reinforcing age stereotypes.

There is a simple test called the Stroop Test. This presents words in different colours to respondents. The words are the name of the colours, for example GREEN. It could, for example, be printed in green. The difficulty comes when the word GREEN is presented in a blue colour. The test measures how successful respondents are at separating conflicting messages like this. The ability to separate the colour and the word is taken as a measure of “executive functioning”. The "executive" manages the workflow in the brain. One of its roles is to avoid distraction. Research using these tests, shows that scores decline with age. The obvious conclusion is that “executive function” declines as we grow older. This is extended to suggest drops in selective attention. Some authors go even further and say that the speed of processing in the brain slows with age. All based on the decline in the results.

Researchers can produce exactly the same kinds of declines in young people. They do this by reducing the colour intensity and contrast of the test. Sight declines with age in exactly these ways. Do the declines measured come from the ageing brain or from the decline in vision? They point out that all tests of mental ability may be subject to declines in the senses.

A large study of intelligence tests looked at the impact of sight and hearing loss. They measured intelligence on multiple scales. They also took objective measures of sight and hearing. The first group were under 70. Declines in sight and hearing accounted for 11% of the variation in measured intelligence. For an over 70’s group that number rose to 31%. Nearly a third of the respondents could not read the tests or hear the instructions.

Many memory tests involve a five minute reading of a passage of information. Memory is then tested by how much the respondent can recall. Across many studies memory was shown to decline with age. Researchers again were able to mimic this apparent decline. This time they added background noise to distort the passage when it was read to young respondents. The distraction mimicked the impact of hearing loss. Without it the experiment showed that memory declined with age. With the distraction added there was no difference between the young and the old. The declines came from hearing loss not the ageing of the brain. When using tests, psychologists need to be sensitive to the impact of declining senses. These same tests are used in the diagnosis of Alzheimer’s disease. A mistake can have life changing impacts.

The reason that the senses have an impact goes beyond the relevant information not reaching the brain. In earlier Newsletters I have pointed out that the eyes are not a camera and the ears not microphones. The senses are integrated with the brain (#025). The brain can and does “fill in the gaps”, if the signal from the senses is not clear. This is the process of perceptual completion (#015 & #031). This requires the mind to engage. Completing a test with a sensory impairment means we can use up ”brain power”. This is precisely what the test is measuring.

The Enemy Within

In earlier Newsletters I have point out the dangers of stereotypes becoming “self-fulfilling”. (#017) We all grow up with stereotypes of what it means to be “old”. In day to day life and in the media, older people are portrayed in a stereotypical way. In general those stereotypes are ageist. They portray a negative “world” of body and brain failing. The stereotype is often applied twenty years too early (#004). This no longer represents todays reality. We are living longer and healthier, mentally and physically.

It is still there in our minds. As we get older, triggering it can undermine us. When triggered it can reduce something as objective as “grip strength”. Respondents tested their strength with a grip meter. They were then reminded of the stereotype of older people being weak and infirm. We all believe in the stereotype. When they were then asked to do the test again, they could not pull as hard (#017).

The same effect happens in psychological testing. Researchers created two different environments in which to administer a memory test. In the first everything created a negative or stressful environment for older people. The setting was a college campus full of young students. This would be unfamiliar to the older respondents. The research assistant was young. The tests were even performed in the afternoon and evenings. This is when more older people are mentally less active. The instructions stressed the memory component of the test.

The positive environment was the opposite. The setting was familiar to older people. The assistant was older, etc.. The older respondents responded to the negative environment. It produced a lower memory score and higher levels of measured stress. Younger adults were not affected by either of the environments.

The most disturbing experiment involved screening for dementia. There are standard tests used to assess the onset of this debilitating disease. The research again manipulated the “enemy within”. In half the cases the respondents were told that both young and old groups would be taking the test. In the other half they added that typically there were no difference in test results by age. The results were depressing for such a minor manipulation.

With the “enemy within” engaged, 40% of the people tested were diagnosed to have the early stages of dementia. Without stimulating the stereotype the rate dropped to 10%. Other studies have shown a difference of 70% versus 14%. Further tests would logically follow such a diagnosis. The authors warn of a potential vicious cycle. Dementia is a terrifying disease. Even a preliminary diagnosis can stimulate a negative self-stereotype. This in turn could undermine memory, when measured subsequently.

There are solutions. The same dementia study was repeated. This time the respondents were briefed on the dangers of stereotypes "taking over". The impact of the different settings disappeared. Results with and without the warnings showed no statistical difference.

Can we trust the data?

There have been many studies on declines in mental ability with age. There are too many to dismiss them all as aberrations of the testing process. What declines there are seem to be coming later in life. The danger for researchers and clinicians alike is their own age stereotypes. These can become self-fulfilling in their interpretation of results.

The psychologists need to be sensitive to the psychology of the testing process.