Attention Across the Lifespan

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

Lin, C. C., C. K. Hsiao, et al. (1999). "Development of sustained attention assessed using the continuous performance test among children 6-15 years of age." J Abnorm Child Psychol 27(5): 403-412.

Carriere, J. S., J. A. Cheyne, et al. (2010). "Age trends for failures of sustained attention." Psychol Aging 25(3): 569-574.

Jackson, J. D. and D. A. Balota (2011). "Mind-wandering in younger and older adults: Converging evidence from the sustained attention to response task and reading for comprehension." Psychol Aging

Image 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

DISORDERED ATTENTION

The marriage between basic science research and clinically relevant research is necessary for extending our understanding of both the former and the latter. Just as studying the natural course of development can shed much light on mechanisms of disease, investigations on such disorders can also tell us much about basic development: since disorders are often manifestations of a “natural process” gone wrong, they often clue us in on the workings of essential processes in normal development. For instance, as this week’s articles suggest, research on attention disorders often informs basic research on attention. In practice, however, these two practices are not really isolated; it’s more of a continuous cycle in which knowledge from basic research (or clinical research) is used to examine diseases (or developmental processes) through the lens of the other discipline. However, there are important pitfalls to this approach. For one, while studying the diseased state can often point to a certain brain region or process involved in maintaining balance in the natural state, it doesn’t necessarily shed light on the exact workings found in the natural state. Rather, it essentially builds an image from negative space: it tells us what should not happen, but not necessarily what does happen.

Bonnelle et. al. (2011) investigated the role of the functional connections in the default mode network (DMN) in predicting attention deficits after traumatic brain injury (TBI). Using neuroimaging techniques, they found that impairments in sustained attention are associated with increased activation of the DMN (shown in figure 1 below). More importantly, the interaction of the precuneus with the rest the default network was predictive of future attention impairments. Here’s the punch line: “predictive information” is present before any behavioral manifestation of attention impairment! By using diffusion tensor imaging (TMI), Bonnelle and his team also found that structural disconnection/low functional connections in the DMN are also predictive of sustained attention deficits (shown in figure 2 below).

FIGURE 1

FIGURE 2

Thus, the authors suggest that abnormalities in DMN function as well as certain functional connections can serve as reliable markers of attention impairments. This conjecture and this study provide a good example of the relationship between basic research and clinically relevant research in the study of attention. By studying patients with attention disorders (TBI patients) and comparing their DMN activation patterns with those of healthy, control patients, we are able to find a potentially new strategy of predicting sustained attention impairments (clinically relevant) using markers in DMN (a natural state process). 

Berman et. al. (2011)’s study expanded upon the then current knowledge of functional connectivity in the DMN and its impact on neurological disorders such as Major Depressive Disorder (MDD). Specifically, they analyzed the connectivity of the DMN in the subgenual cingulate both on and off-task to examine the relationship between connectivity and rumination. The authors found patients with MDD demonstrated more functional connectivity between the posterior-cinguate cortex and the subgenual-cingulate cortex compared to healthy individuals during rest periods, but not during tasks. Importantly, this functional connectivity was correlated with rumination and brooding. The figure below shows this phenomenon. As one can see, the MDD group differs notably from the HC group only during off-task periods, just as the relationship between rumination and connectivity exists only during off-task periods.

Personally, this was my favorite paper this week because I think it really sheds light on the workings of depression and potentially new targets and treatment options for patients with MDD. I don’t have any experience with MDD personally, so I can only imagine what it must be like for these patients. I do remember reading Kay Redfield Jamison’s memoir, An Unquiet Mind, in which she recounts her battle with bipolar disorder, and I will never forget her description of depression:

In its severe forms, depression paralyzes all of the otherwise vital forces that make us human, leaving instead a bleak, despairing, desperate, and deadened state…Life is bloodless, pulseless, and yet present enough to allow a suffocating horror and pain. All bearings are lost; all things are dark and drained of feeling. The slippage into futility is first gradual, then utter. Thought, which is as pervasively affected by depression as mood, is morbid, confused, and stuporous. It is also vacillating, ruminative, indecisive, and self-castigating. The body is bone-weary; there is no will; nothing is that is not an effort, and nothing at all seems worth it. Sleep is fragmented, elusive, or all-consuming. Like an unstable, gas, an irritable exhaustion seeps into every crevice of thought and action.

I truly hope the authors take this study further and work towards a future treatment option for patients with major depressive disorder.

Saytte et. al. (2009)’s study involves (almost) every college student’s best friend. It usually comes in a red plastic cup and having the first one makes having the second and third ones seem like a really good idea. 

Saytte and his team investigated the effects of alcohol consumption on consciousness and meta-consciousness. Specifically, fifty-four male social drinkers were given either alcohol (0.82g alcohol/kg of body weight) or a placebo beverage and subsequently asked to perform a mind-wandering reading task. The key aspect of this experiment was the fact that both self-caught and probe-caught “zone-outs” were utilized, thus allowing the authors to differentiate between mind-wandering “inside and outside of awareness.” The authors found that subjects given the alcohol exhibited more probe-caught zoning out episodes compared to subjects given the placebo drink. Thus, subjects given alcohol not only demonstrated a greater degree of mind wandering, but also had a reduced probability of catching themselves. Indeed, the experimental group engaged in mind wandering without awareness 25% of the time. Based on these results, the authors conclude that alcohol impairs individuals’ meta-awareness of their current thoughts. I think this study was really well designed because it provided a true experiment on human subjects in an area of study where such real experiments often cannot be done due to obvious ethical reasons. For instance, the two previous studies examined patient groups and compared them with control groups. Thus, their studies, while rigorous and informative, do not constitute true experiments. In this study, Saytte and colleagues were actually able to manipulate a variable and examine the effects of that manipulation in an ethical way to provide important information on mind-wandering and consciousness.

Manly et. al. (2001) provide a new battery of tests, namely the Test of Everyday Attention for Children (TEA-Ch), for evaluating children’s attention. TEA-Ch is composed of nine subsets taken and modified from adult attentional measures. By evaluating the performance of 293 healthy children in TEA-Ch, the authors evaluated the reliability of TEA-Ch in predicting attention in children. The second part of this study involved evaluating the performance of 24 children with ADHD on TEA-Ch. While results from TEA-Ch indicated that these children had deficits in performance on all of the TEA-Ch measures (except the Sky Search task), they did not shed much light on the extent to which attention skills were impaired. The authors conclude that the subsets of the TEA-Ch are in fact not measures of attention, but of auditory and visual detection, counting and response speed, etc.

            I think the main interest this article had for me was noting the differences between children and adults in their attention patterns and thus the need for specialized tests for children, which should be different from those for adults, in diagnosing attention disorders such as ADHD and ADD. While I recognize that severe forms of these diseases need treatment and medication, there have been too many cases of extremely young children who were diagnosed with ADD or ADHD being unnecessarily drugged due to flaws in the diagnosis system. Most children are naturally more active; it is important to develop a specialized test sequence for children and thus be absolutely sure that a child needs mediation before prescribing one.

Some Further Comments/Possible Future Investigations

When I read about the possible role of DMN’s interaction with the rest of the brain in promoting a “coordinated balance between internally and externally directed thought,” I was reminded of schizophrenia. Although we know very little about schizophrenia, we do know that a hallmark of this disease is uncontrolled internal thoughts. For instance, patients report hearing voices that compel them to perform certain actions. I would be extremely interested to see the role that the DMN plays in schizophrenia and the different activation patterns and functional connections in the DMN in healthy individuals and patients with schizophrenia.

References

Bonnelle, V., R. Leech, et al. (2011). "Default Mode Network Connectivity Predicts Sustained Attention Deficits after Traumatic Brain Injury." J Neurosci 31(38): 13442-13451.

Berman, M. G., Peltier, S., Nee, D. E., Kross, E., Deldin, P. J., & Jonides, J. (2011). Depression, rumination and the default network. Soc Cogn Affect Neurosci, 6(5), 548-555.

Sayette, M. A., E. D. Reichle, et al. (2009). "Lost in the sauce: the effects of alcohol on mind wandering." Psychol Sci 20(6): 747-752.

Manly, T., V. Anderson, et al. (2001). "The differential assessment of children's attention: the Test of Everyday Attention for Children (TEA-Ch), normative sample and ADHD performance." J Child Psychol Psychiatry 42(8): 1065-1081.

Image References

What is a Hangover? http://gizmodo.com/tequila/. Accessed 03/10/2013. 

http://clinica2m.ru/news.html. Accessed 03/10/2013. 

Mindfulness and Meditation Based Attentional Training

Meditation is a century year old practice that I experienced firsthand this week at the New York Insight Meditation Center. Clearly, the notion of meditation usually brings to mind an image of Buddha sitting at peace. Since it was my first time however, I didn’t know what to expect, and had a multitude of questions about the practice. Why’s the purpose of meditation? The ultimate aim? Are there different types of meditation? What are the advantages associated with meditation? The readings for this week shed light on several of these questions, and together with my experience in my first meditation session, gave me a much clearer sense of both the process and end goal of meditation. We begin with a brief overview of the readings for this week and follow with a description of the meditation session, with particular emphasis on its relationship to mind wandering.

Before going to the meditation session, I read up on the research concerning this practice, and I was surprised to find that meditation is a rather varied practice that had clear advantages. I always thought that the increased sense of peace associated with meditation came from simply resting the body more so than the mind. This week’s readings as well as my own meditation session refuted this conjecture. Indeed, the session included an emphasis on the power of the mind in focusing on the task at hand such as following the breath and relaxing certain areas of the body as well as in broader endeavors such as reaching acceptance.

Thus, one can say that “mindfulness,” as defined by Baer et. al. (2006), was an important component of my meditation session. In accordance with the instructor’s talk, Baer and his colleagues found that mindfulness, defined as “bringing one’s complete attention to the experiences occurring in the present moment, in a nonjudgmental or accepting way,” can be developed with regular meditation. Furthermore, the authors also mention that mindfulness can lead to increases in qualities such as awareness, compassion, and equanimity. In their study, the authors used questionnaires to measure awareness, nonjudgemental “present-moment observation and openness to negative experience,” and “acting with awareness…accepting without judgment.” The found that the results of the questionnaires demonstrated internal consistency and showed that mindfulness correlated such several other variables, thus making the questionnaires psychometrically promising tools.

Lutz et. al. (2008)’s report focused more on the practice of meditation itself rather than on a certain characteristic/result of  meditation. Specifically, Lutz and their colleagues defined two types of meditation, namely focused attention (FA) and open monitoring (OM) meditation. FA meditation, like its name suggests, refers to focusing thought on a selected object and maintaining attention only on the present task/object while minimizing distraction and intrusive thoughts. On the other hand, open monitoring (OM) meditation involves “non-reactively monitoring” thoughts as they occur from moment to moment, allowing the mind to wander as a means to experience and appreciate one’s “emotional and cognitive patterns.” Thus, FA meditation is more involved in training the mind whereas OM meditation allows us to experience the mind by accepting the thoughts that cross it.

Clearly, the characteristics of FA meditation (such as focus on one object or task) are reminiscent of vigilance and the characteristics associated with sustained attention. MacLean et. al. (2010) saw this connection and performed a study on whether FA meditation led to improvements in sustained attention. The authors found increased visual discrimination as well as improvements in vigilance/sustained attention tasks as a result of meditation training. These results suggest that intensive FA meditation involving attention on nonvisual perceptions such as breath indeed generalizes to improved visual perception during vigilance tasks. I found this to be particularly interesting because it suggests that meditation training resulted in an improvement of mind and not just an increased peace in body. I would be interested to see whether meditation leads to improved performance on other types of vigilance tasks not including visual perception.

Jensen et. al. (2012) addressed a possible confounding factor in MacLean et. al.’s 2010 study. Although the investigation had compelling results, Jensen questioned whether the improvements were actually the result of increased attention. Specifically, Jensen and colleagues propose that these improvements could have been the result of increased “attentional effort,” and thus reflect the subject’s willingness to focus attention on a selected object or during a vigilance task and not the subject’s ability to do so. In their study, they tested 48 healthy subjects without previous meditation training were assigned to groups with differing mindfulness (mindfulness-based stress reduction/MBSR and non-mindfulness based stress reduction/NMSR) and incentive levels. The premise is that the “incentive” group will have greater motivation and willingness to perform—and thus exhibit a greater attentional effort. The authors found that attentional effects of MBSR, NMSR, and the incentive groups were comparative, though slightly greater in the incentive group. However, only the MBSR group exhibited notable improvements in selective attention and an improved threshold for “conscious perception and visual working memory capacity.” Therefore, the authors argue that MBSR may contribute uniquely to attentiaonl improvements but further research on the effect of test effort is needed before one can make a conclusions such as that of MacLean et. al. In essence, Jensen’s study serves as a cautionary tale to account for the presence of confounding variables in the study of attention.

Clearly, after reading these reports and looking up interesting pictures of meditation, I had a conglomeration of different expectations for what my first meditation session would be like. Personally, in my mind, meditation reminds me of Rafiki (the wise old baboon) from the Lion King more than anything else. He meditates on a rock just before leading Simba to the vision of his father and motivating him to accept the past, move on, and embrace the future. If you can’t tell, Lion King was my favorite childhood Disney movie. And Rafiki was my favorite character. On to (real) meditation! The session began with sitting meditation, in which we assumed a restful sitting position and concentrated on our breath. This focus was paired with instructions to relax certain areas of our body in sequence. Occasionally, the instructor would ring the gong three times during our meditation session. I found this session to be a mixture of both FA and OM meditation, as defined in Lutz et. al. For instance, our instructor encouraged us to focus on our breath and to not let our minds stray or wander. However, he also encouraged us to let our thoughts pass through our minds one by one. Regarding mind wandering, he told us to “be gentle with yourselves;” because of the power of the mind, he said that mind wandering is inevitable, especially during a beginning meditation session. “When your mind wanders, just gently bring yourself back to the breath and focus on that.” Thus, I found it interesting that the session included both types of meditation. The second half of the session, and the one I found to be most interesting, was a discussion on the practice and benefits of meditation. Through personal anecdotes, our instructor elaborated on the power of meditation to foster acceptance and “clearing.” By focusing the mind and becoming one with the universal “self,” meditation helps us see the interconnectedness of everyone in society. In particular, he talked about how meditation led to positive changes in his life by enabling him to release the negativity and move on from tragic events and find peace and acceptance.

I found this week’s readings and in particular, this week’s meditation session, extremely informative both academically and personally. My experience this week helped me understand meditation in a broader light and shed light on how it could positively contribute to a more accepting and positive life.

Word Count: 1289, not including references :D 

References

Lutz, A., H. A. Slagter, et al. (2008). "Attention regulation and monitoring in meditation."

Trends Cogn Sci 12(4): 163-169.

MacLean, K. A., E. Ferrer, et al. (2010). "Intensive meditation training improves perceptual discrimination and sustained attention." Psychol Sci 21(6): 829-839.

Jensen, C. G., S. Vangkilde, et al. (2011). "Mindfulness training affects attention-or is it attentional effort?" J Exp Psychol Gen.

Baer, R. A., G. T. Smith, et al. (2006). "Using self-report assessment methods to explore facets of mindfulness." Assessment 13(1): 27-45.

Image References

The Lion King—Meditating Rfiki. http://findingmickey.squarespace.com/disney-animated-features/the-lion-king/9161332

7 Health Benefits of Meditation. http://foodmatters.tv/articles-1/7-health-benefits-of-meditation