Memory decline is a ‘change’, not a ‘slowing down’

Old woman thinking
When our participants tried to remember things, they tended to use the last thing they said as a cue. For example, if a person says ‘cat’, they may go on to remember ‘lion’, ‘giraffe’, and so on. As people get older, evidence indicates that their ability to hold onto the last thing they said deteriorates...
Dr Thomas Hills
The findings of a study conducted by academics at the University of Warwick suggest that rather than experiencing a general ‘slowing down’ in mental processing speed, elderly people undergo changes in the way that they access their memories. The researchers, whose results have been published in the journal Developmental Psychology, believe that by employing ‘foraging’ strategies, individuals might be able to slow memory decline.

The scientists conducted an ‘animal fluency test’ on a group of 185 participants aged between 29 and 99. Respondents were asked to name as many animals as they could within a three-minute time period. It has long since been known that performance on this type of test tends to deteriorate in line with a subject’s age. However, the academics discovered that this decline is largely due to changes in the way that older participants remember information – not because of a slowing in mental processing, as was previously believed.

Mental foraging


The team likened the phenomenon to a bird that stops foraging in a berry-laden bush before it has had chance to collect all of the available fruit. The results indicate that elderly people tend to move on from one ‘patch’ of memory to another before they have had time to fully exploit the information contained within.

"Both our research and previous studies suggest that memory decline tends to begin during a person’s mid 70s," participating scientist Dr Thomas Hills told ScienceOmega.com. "This is quite surprising when you think about it. You have to be pretty old before you start to experience age-related memory loss."

Historically, memory decline has been thought of as a general slowing down in an individual’s mental processing speed. However, Dr Hills, an Associate Professor at the University of Warwick’s Department of Psychology, prefers to describe this process as a change in how people of different ages access their memories. It is not yet clear whether the nature of this change is physiological, or whether it fulfils some sort of strategic objective.

"You might imagine that as people get older, they adjust their strategy in terms of the way they search their memories," he explained. "Equally, it could be some type of physiological change that reconfigures the search parameters within a person’s head. Our data cannot really say which explanation is most accurate. However, previous research demonstrates that as people age, they lose their ‘working memory’ capacity. They become less capable of holding information in their minds whilst simultaneously conducting a secondary task.

'Working memory capacity'


"Our findings are consistent with this research," continued Dr Hills. "When our participants tried to remember things, they tended to use the last thing they said as a cue. For example, if a person says ‘cat’, they may go on to remember ‘lion’, ‘giraffe’, and so on. As people get older, evidence indicates that their ability to hold onto the last thing they said deteriorates; they lose their working memory capacity."

The team found that older people were less able to deal with the demands of the animal fluency test than younger participants. Typically, respondents approach this task by accessing a semantically distinct patch of memory – for example, one related to pets. They might begin by listing dogs, cats, rabbits, etc. However, as the number of animals contained within this patch is depleted, answers become less easily accessible. In turn, subjects will begin to look towards other animal-related patches.

The study revealed that older participants ‘flit’ from patch to patch more often than their younger counterparts. Essentially, older people move on from a semantic resource before they have obtained the optimal benefit. Younger people, on the other hand, find it easier to identify the best time to switch. Dr Hills and his colleagues contend that by making a conscious effort to explore each semantic patch in full, older people might be able to improve their memory performance.

"Further research will be necessary before we are able to make any concrete assertions in this area," he said. "However, I think that it might be possible to help individuals suffering from memory decline to relearn how to use linguistic cues. Perhaps this could be achieved by encouraging individuals to write things down. Alternatively, one might conduct simple word association techniques. Such strategies could help to reduce the amount of mental ‘jumping around’ that a person does."

The results of the study could also prove useful in the fight against other cognitive disorders.

"A number of our current projects are focusing specifically on dementia," Dr Hills concluded. "What happens as a person develops dementia? Is it possible to predict the onset of dementia by examining the ways in which people recall information? These are the types of question that we are interested in answering."

In the meantime, by concentrating on verbal cues and by employing foraging techniques, older individuals might be able to keep memory decline at bay.

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