Research attention across an
individual’s lifespan presents several significant challenges such as
establishing a controlled environment in which to measure subjects’ attention
and minimizing the presence of confounding factors. Researchers have arisen to the
task, however, and have developed several techniques to overcome these
challenges; yet, while these strategies have greatly addressed several
important challenges, many still remain to be overcome. This week’s papers shed
light on both the challenges facing researching attention across lifespans and
the methods researchers have developed to overcome them.
Lin et. al. (1999) studied the development of sustained attention
as a function of age and sex via administering the Continuous Performance Test
(CPT) to 341 children between the ages
of six and fifteen. I found the author’s choice of CPT as a measure of
sustained attention development very interesting since it’s not the standard
test for studies of “normal” attention. Rather, it has been primarily employed
as a measure of deficits in sustained attention in children
with attention disorders such as ADHD and for identifying children with high
risk of developing schizophrenia. Along this vein, however, the usage of CPT in
this study does make the results much more clinically relevant, which may be
one reason why CPT is used instead of more conventional measures such as SART. Briefly,
CPT requires the subject to respond to targets embedded in background stimuli
that’s presented at a rapid, fixed rate. However, in this discrimination task,
the target can be either a single stimulus or a set of two successive stimuli,
thus allowing the researchers to alter the difficulty of the task. Furthermore,
relative targets and stimuli blurring can also be employed to further heighten
the challenge of the task.
The researchers employed two versions of CPT,
namely undegraded and (25%) degaded, in this study and analyzed the
relationships between age/sex of the subjects and the corresponding hit rate,
false alarm rate, and sensitivity. Through performing multiple regression
analyses, the authors found that all three variables (hit rate, false alarm
rate, and sensitivity) of both the degraded and undegraded CPT shared a
quadratic relationship with age, as shown in the above figure. Furthermore, the
age-development curves for the hit rate and sensitivity were both convex,
whereas the false alarm rate curve was concave. These results suggest that
sustained attention develops during “the primary school ages,” well before age
15.
One thing I found especially interesting is the
authors’ claim that this study’s results can be very important in identifying
children with neurological conditions characterized by deficits in sustained
attention, such as ADHD and schizophrenia. While I think that it’s absolutely
wonderful that this study could contribute to early detection of devastating
disease such as schizophrenia, I still stand by what I said in previous posts,
namely that researchers and doctors should be extremely careful in prescribing
medicine to young children. Sometimes, deficits in sustained attention,
especially slight deficits, are just that, and don’t necessarily warrant
prescriptions of anti-psychotic drugs, which may do more harm than good for
still developing children. All in all, however, I think this was a well carried
out study with many important areas for development and possible clinical
applications.
Carriere
et. al. (2010)’s
study truly fit the description of researching attention across the lifespan.
In contrast to natural expectations, previous studies have shown an
“age-related reduction” in errors on sustained tasks, a result that suggest
sustained attention abilities improves with age. This is a paradoxical result
at best given what we know about the aging brain and decreases in working
memory that oftentimes accompany age. It would not be surprising if a confounding
variable were present; as such, this is a great example of the difficulty and
challenges embedded in researching attention across lifespans. Carriere and his
team investigated this phenomenon, in particular failures in sustained
attention as a function of age, via measuring SART (sustained attention to
response task) performance of 638 individuals with ages ranging from 14 to 77
years old. The results provide a sound explanation of the perplexing finding
reported in previous studies.
Whereas older subjects made fewer errors on SART tasks to be sure, they also exhibited slower responses. Indeed, the reduction in SART errors demonstrated by older subjects can be at least partially attributed to their slower response rates, as they have more time to think and analyze before answering. Furthermore, in accordance with previous findings, the reduction in sustained attention errors decreased in a linear fashion with increasing age; the more novel finding was a similar linear decrease in response speed as a function of increasing age. These trends are shown in the above figure. On the other hand, the authors fond that task disengagement (as measured by anticipations and omissions, etc.) decreased in early adulthood and then remained stable for the remaining (older) ages. These results indicate that the seeming increase in sustained attention ability suggested by previous research is actually the result of two factors that determine performance on sustained attention tasks: response rate and actual sustained attention. Specifically, while sustained attention (measured by task engagement and disengagement) definitely improves with age early on in life, it reaches a stable point in young adulthood and then remains relatively unchanged. Furthermore, as the authors themselves note, these improvements can be attributed to “maturation rather than aging” in the older subjects. In addition to sustained attention changes, response rates also decrease with increasing age, which may lead to reduction in SART errors associated with task disengagement or mind wandering.
I think this report does a really good job of
addressing a possible confounding factor (response time) present in previous
studies on sustained attention across a wide range of ranges. I would be
extremely interested to see this study replicated using a test with greater
working memory capacity demands to asses the balance between reduction in
sustained attention errors and decrease in working memory capacity in the older
subjects. At what point do potential reductions in working memory associated
with age balance out improvements in sustained attention task performance
associated with maturation and response time?
Jackson et. al. (2011)
compared mind wandering
tendencies and patterns in younger and older adults. In contrast to Carriere et. al. and similar reports, which
reported “increased sustained attention” as a function of age, Jackson et. al. notes “goal neglect” may be one
explanation of the changes associated with older adults’ cognitive
performances. Method-wise, the authors used three versions of SART and a
reading comprehension task. Specifically, the authors measured response
latencies on GO trails both immediately before and after NOGO errors. For the
reading comprehension task, subjects were asked to read an excerpt from War and Peace with both probe-caught and
self-caught mind-wandering.
Results were in accordance with previous
literature; findings indicated that older adults do not exhibit more mind
wandering than younger adults, and even exhibit less mind-wandering on certain
trails. For instance, both younger and older adults produced comparable
pre-error speeding, a measure of mind-wandering and task-disengagement.
However, analysis with probe-caught mind wandering revealed older adults
consistently reported less mind
wandering than younger adults. Whereas younger adults reported mind-wandering
at a rate of 44%, older adults only reported mind-wandering 16% of the time. One
possible explanation for older adults’ reduction in mind wandering could be
attributed to the fact that older adults found the reading more interesting and
difficult than the younger adults. Thus, they were more motivated to stay
on-task than young adults.
A particular interesting pattern that emerged
from these experiments was a clear “disproportionate” post-error slowing
exhibited by older adults. Classically, post error slowing has been attributed
to “the process of redirecting attention to the primary task after an error is
detected.” The authors suggest two
possible explanations for this phenomenon. For one, this slowing may be due to
older adults’ impairment in task re-engagement, and thus the post-error slowing
may reflect a decline of cognitive control reestablishment in older adults. On
the other hand, this post-error slowing could also reflect “task-related
mind-wandering.” In brief, supporters of this view maintain subjects engage in
a type of self-evaluation upon making an error, which lead to internal and
task-relevant mind-wandering. Since older adults found the task more
interesting than younger adults, it makes sense that they would be more likely
to engage in task-related mind wandering and self-evaluation following an
error.
This report further illustrates the challenges
of researching attention across lifespans. Probably one of the most pressing
hurdles is the extreme difficulty in performing a true experiment under ideally
controlled conditions in studies on attention across a lifespan. Clearly, one
can’t alter subjects’ age to their will anymore than they can control confounding
factors that often come with age and experience. Yet, despite these significant
challenges, I think the papers that we read for this week are testaments to the
creative methods researchers have developed to address these challenges.
References
Lifespan Developmental Psychology Laboratory. http://www.brandeis.edu/departments/psych/lachman/index.html
http://www.therpf.com/f9/question-time-turner-harry-potter-80022/
http://thebluebookcase.blogspot.com/2010/11/post-reading-war-and-peace.html
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