Elderly can be as fast as
young in some brain tasks, study shows
December 28, 2011 – Both children and the
elderly have slower response times when they
have to make quick decisions in some
settings.
But recent research suggests that much of
that slower response is a conscious choice
to emphasize accuracy over speed.
In fact, healthy older people can be trained
to respond faster in some decision-making
tasks without hurting their accuracy –
meaning their cognitive skills in this area
aren’t so different from younger adults.
“Many people think that it is just natural
for older people’s brains to slow down as
they age, but we’re finding that isn’t
always true,” said Roger
Ratcliff, professor of psychology
at Ohio State University and
co-author of the studies.
“At least in some situations, 70-year-olds
may have response times similar to those of
25-year olds.”
Ratcliff and his colleagues have been
studying cognitive processes and aging in
their lab for about a decade. In a new
study published online this month in the
journal Child
Development, they extended
their work to children.
Ratcliff said their results in children are
what most scientists would have expected:
very young children have slower response
times and poorer accuracy compared to
adults, and these improve as the children
mature.
But the more interesting finding is that
older adults don’t necessarily have slower
brain processing than younger people, said Gail
McKoon, professor of psychology
at Ohio State and co-author of the studies.
“Older people don’t want to make any errors
at all, and that causes them to slow down.
We found that it is difficult to get them
out of the habit, but they can with
practice,” McKoon said.
Researchers uncovered this surprising
finding by using a model
developed by Ratcliff that
considers both the reaction time and the
accuracy shown by participants in speeded
tasks. Most models only consider one
of these variables.
“If you look at aging research, you find
some studies that show older people are not
impaired in accuracy, but other studies that
show that older people do suffer when it
comes to speed. What this model does
is look at both together to reconcile the
results,” Ratcliff said.
Ratcliff, McKoon and their colleagues have
used several of the same experiments in
children, young adults and the elderly.
In one experiment, participants are seated
in front of a computer screen. Asterisks
appear on the screen and the participants
have to decide as quickly as possible
whether there is a “small” number (31-50) or
a “large” number (51-70) of asterisks.
They press one of two keys on the keyboard,
depending on their answer.
In another experiment, participants are
again seated in front of a computer screen
and are shown a string of letters.
They have to decide whether those letters
are a word in English or not. Some
strings are easy (the nonwords are a random
string of letters) and some are hard (the
nonwords are pronounceable, such as
“nerse”).
In the Child Development study, the
researchers used the asterisk test on second
and third graders, fourth and fifth graders,
ninth and tenth graders, and college-aged
adults. Third graders and college-aged
adults participated in the word/nonword
test.
The results showed that there was a rise in
accuracy and decrease in response time on
both tasks from the second and third-graders
to the college-age adults.
The younger children took longer than older
children and adults to respond in the
experiment, Ratcliff said. They, like
the elderly, were taking longer to make up
their mind. But the younger children
were also less accurate than younger adults
in this study.
“Younger children are not able to make as
good of use of the information they are
presented, so they are less accurate,”
Ratcliff said. “That improves as they
mature.”
Older adults show a different pattern.
In a study published in the journal Cognitive
Psychology, Ratcliff and
colleagues compared college-age subjects,
older adults aged 60-74, and older adults
aged 75-90. They used the same
asterisk and word/nonword tests that were in
the Child Development study. They
found that there was little difference in
accuracy among the groups, even the oldest
of participants.
However, the college students had faster
response times than did the 60-74 year olds,
who were faster than the 75-90 year olds.
But the slower response times are not all
the result of a decline in skills among
older adults. In a previous study, the
researchers encouraged older adults to go
faster on these same tests. When they
did, the difference in their response times
compared to college-age students decreased
significantly.
“For these simple tasks, decision-making
speed and accuracy is intact even up to 85
and 90 years old,” McKoon said.
That doesn’t mean there are no effects of
aging on decision-making speed and accuracy,
Ratcliff said. In a study in the Journal
of Experimental Psychology: General,
Ratcliff, McKoon and another colleague found
(like in studies from other laboratories)
that accuracy for “associative memory” does
decline as people age. For example,
older people were much less likely to
remember if they had studied a pair of words
together than did younger adults.
But Ratcliff said that, overall, their
research suggests there should be greater
optimism about the cognitive skills of
seniors.
“The older view was that all cognitive
processes decline at the same rate as people
age,” Ratcliff said.
“We’re finding that there isn’t such a
uniform decline. There are some things
that older people do nearly as well as young
people.”
Ratcliff co-authored the Child Development
paper with Jessica Love and John Opfer of
Ohio State and Clarissa Thompson of the University
of Oklahoma. Ratcliff and
McKoon co-authored the Cognitive
Psychology and Journal of
Experimental Psychology: Generalpapers
with Anjali Thapar of Bryn
Mawr College.
Some of the research was supported with
grants from the National
Institute on Aging and the National
Institute of Mental Health.
