Increasing knowledge decreases human brain's capacity, scientists say
Age mellows all, says the famous saying. Traditionally it is thought that age leads to a steady deterioration of brain function.
However, a study has for the first time argued that older brains may take longer to process ever increasing amounts of knowledge, and this has often been misidentified as declining capacity.
Experts now say that accumulation of years of wisdom and increased knowledge about the world and surroundings slow down human brain function as they age, much like what happens to the hard drive of a computer which is full.
Older brains slow due to greater experience, rather than cognitive decline, the study now says.
The study, led by Dr Michael Ramscar of theUniversity of Tuebingen takes a critical look at the measures that are usually thought to show that our cognitive abilities decline across adulthood. Instead of finding evidence of decline, the team discovered that most standard cognitive measures are flawed, confusing increased knowledge for declining capacity.
Dr Ramscar's team used computers, programmed to act as though they were humans, to read a certain amount each day, learning new things along the way.
When the researchers let a computer "read" a limited amount, its performance on cognitive tests resembled that of a young adult.
However, if the same computer was exposed data which represented a lifetime of experiences its performance looked like that of an older adult. Often it was slower, not because its processing capacity had declined, but because increased "experience" had caused the computer's database to grow, giving it more data to process, and that processing takes time.
"What does this finding mean for our understanding of our ageing minds, for example older adults' increased difficulties with word recall? These are traditionally thought to reveal how our memory for words deteriorates with age, but Big Data adds a twist to this idea," said Dr Ramscar.
"Technology now allows researchers to make quantitative estimates about the number of words an adult can be expected to learn across a lifetime, enabling the team to separate the challenge that increasing knowledge poses to memory from the actual performance of memory itself".
"Imagine someone who knows two people's birthdays and can recall them almost perfectly. Would you really want to say that person has a better memory than a person who knows the birthdays of 2000 people, but can only match the right person to the right birthday nine times out of ten?" asks Ramscar.