Absence of Evidence Is Not Evidence of Absence

It is hard to realize the existence of realities that that we cannot see or measure. This was impressed on me when I recently visited a planetarium in which the audience and I viewed a map of the universe created by the Hubble space camera. The camera had taken many successive snapshots of the sky as it moved along its orbit, saving each adjacent shot side by side. The overall result, projected on the curved ceiling of the presentation hall, looks like a bow tie. If we did not know any better, we would think that the universe actually has this structure, with nothing outside the three-dimensional bow tie. The confusion arises if we don’t realize that the camera is located in the center of its horizon view. The camera’s horizon is constrained by its orbit. To get a better mapping, it would have to create maps from all points in all theoretical orbits around the earth.

 

In this case, the evidence for a relatively homogeneous three-dimensional universe caused a central black hole explosion is missing. We might erroneously conclude that the “big bang” theory is wrong. But absence of evidence is not necessarily evidence of absence. This principle emerges in another context when we say that certain phenomena are “immaterial.” Material things have a chemistry and physics, and things that do not seem explainable in those terms are often called “immaterial.”

 

What about things we call “abstract,” such as probability? Probability is not defined as a reality but rather the likelihood that a certain reality may emerge. In Shannon’s Information Theory, for example, “information” would not be regarded as a material reality as such but rather as the probability that a certain material event may occur. Indeed, information’s lack of material reality was probably why Shannon chose to define it the way he did. Probability ideas apply to much of the “spooky” aspect of quantum mechanics.

 

In the field of neuroscience, many scholars use the words “immaterial force” to explain consciousness. Yet, how can a force have the force of mediating our thoughts and willed action if it is immaterial? In the field of religion, many theologians use the word immaterial to explain the soul as some kind of immaterial form of being. How can something “be” and yet not be?

 

Neither case explains anything. In both cases, “immaterial” is intended to have the circular definition of not being material. What can this word possibly mean? To claim that something is immaterial is to imply that it does not exist. We know from personal experience that consciousness surely exists, and there are many good reasons to believe that souls exist too.

 

A fundamental premise of science is that all things are material, including those things that we cannot explain in material terms. Here is a list of material phenomena that were originally thought by many to be immaterial, because at the time there was no evidence for a material explanation:

 

·       The germ theory of disease

·       Immunity to infection

·       X-rays and other portions of the electromagnetic spectrum

·       Heat and cold

·       Gravity

·       Curved space-time

·       Quantum mechanics

·       Unconscious Mind

 

Quantum mechanics is of particular interest and relevance to this issue. Numerous experiments have demonstrated that observing something, even if just by a laboratory instrument, can make apparent physical realities we did not know existed. Matter can go from one spot to another without moving through the intervening space (called quantum tunneling). Information moves instantly (faster than the speed of light) across vast distances. Clearly, this does not reflect the kind of reality we ordinarily experience. Yet it exists.

 

Two explanations are possible. One is that the act of observation actually creates the manifest physical phenomena. Another is that the physical properties were pre-existent in inapparent form. Neither possibility makes sense in terms of our present knowledge. While many physicists can describe quantum phenomena, no one can explain them. Nonetheless, the facts are demonstrable.

 

What then is meant by material reality? Real things can seem unreal (immaterial?) under certain circumstances. This  perspective suggests that everything could be material, though sometimes that material reality may not always be apparent. Most likely, things we think of today as immaterial, such as consciousness and soul, are real material phenomena that we think must be immaterial because we have not yet discovered their material nature.

 

Science, by definition, MUST deal exclusively with material things. It is not possible for things to exist and yet not exist because they are immaterial. Thus, those who cling to immateriality are obliged to defend their position with compelling logic and evidence, if there were any. The rest of us are left with the conclusion that everything is material, though sometimes that material reality may not always be apparent. This surely can apply to consciousness and the soul. Considering consciousness or the soul as immaterial precludes any possibility that science is relevant to these phenomena. On the other hand, if consciousness and the soul have a material reality that is not yet apparent, then science might find evidence to help document and explain those realities.

 

Mind Control. You Can Have More Self Control than You Think

 

Who’s in charge in deciding what your brain thinks about? Many factors are involved, but you have more control than you might think.

Everyone has some degree of self-control that affects their beliefs, desires, thoughts, goals, plans, and feelings. Humans are unique in their capacity for self-control, which is generally assumed to arise from the relatively large frontal cortex in the brain. The neocortex even has a series of linked circuits that constitute an executive control system. Lack of self-control underlies many social and mental health problems. Failing at self-regulation can lead to obesity, addiction, poverty, sexual promiscuity, and other ill-advised behaviors. On the other hand, people with superior self-control are more likely to be "healthy, wealthy, and wise."

How do we learn such control? I identify five factors:

1.    Motivation

We are motivated by the brain's positive reinforcement mechanisms and our mental ability to adjust the set point for the level of reinforcement that satisfies us. Like a heater thermostat, if the setting is low, it doesn't take much heat to meet the demand. If the setting is high, we need more heat and for longer periods. How does one adjust the personal hedonistic set point?

One way to increase self-control is to have many alternative positive reinforcers that allow one to substitute "good" reinforcers for bad ones. Another way is to structure goals consciously so that achievement requires "good" reinforcers. You can seek the company of fellow beings who wish to share those same values and guidelines. Incentives matter.

2.    Mental Fatigue

Resisting temptation can be hard work. In secular life, we get refreshment from taking a vacation. Taking a vacation from resisting temptation is hardly the righteous choice. What then, do we do to refresh the self-control required for resisting temptation?

Capacity for self-control is apparently a "limited resource" that can be depleted. Replenishment takes time in which there are fewer demands. Maybe this is one advantage of vacations or retreats. Escape from tempting situations is akin to taking a vacation.

Our own negative thoughts wear us out. Distressing thoughts make it all too easy to obsess to the point of emotional exhaustion. Think of all the times you have lost sleep over something that troubles you. When awake, such obsession diminishes our productivity.  How do we inhibit such obsessive thought? Mental discipline is required. There are ways to train the brain to be more disciplined at screening out intrusive thoughts. One method, strangely enough, involves working-memory training tasks; these train the brain to focus and screen out distracting thought.[1]  Habitual intense prayer or meditation may do the same thing.

3.    Age

Young people usually have less self-control that adults. Educators assert that self-control in preschool-aged children is more associated with school success than is IQ.[2] Brain dysfunctions that alter self-control will increase impulsivity and often lead to anti-social and even violent behavior. Brain scans show that impulsive people have an abnormally small hippocampus and prefrontal cortex.[3] We don’t know if they were born that way or got that way by a lifetime of indulging their impulses.

Executive control capability may decline in the elderly, who may become less able to take care of their needs and control their life. A study of seniors (average age of 75) revealed a tendency for elderly to withdraw from social interactions, along with an associated tendency to become depressed.[4] Stress, which may well have a cumulative effect over the years, is compounded by the current stresses of old age. The adrenal-pituitary stress axis may be more active, resulting in a high blood pressure from adrenalin release and shriveling of neural synapses from excessive cortisol release.

Biochemical markers of inflammation increase with age. The cumulative stresses of a lifetime can cause increased anxiety, confusion, further stress, and depression. Thus, a vicious cycle of mental deterioration may ensue. In such a state, executive control fails, and the person may become helpless and dependent.

4.    Religion

"Mind over matter" is a central theme in most religions. The idea is that proper spiritual belief gives you the strength to cope with the vicissitudes of life. Paradoxically, the most religious people, like monks, may not use their strength of faith to cope with life but actually escape worldly stress by living in monasteries or nunneries.

Literature surveys reveal a strong relationship between religiosity and self-control. Self-control in religious people is manifest in that they tend to suffer less from depression, avoid trouble with sex or drugs, do better in school, and even visit the dentist more regularly. It is not clear whether religious experiences promote self-discipline or whether a self-disciplined person is more likely to respond to the self-control requirements of religion. It could be both. Whatever the case, to be mentally and spiritually healthy, we must learn to discipline our thinking, just as we discipline our body to improve our golf game or other physical skills.

An interesting survey of 213 people measured both the degree of self-control and religiosity.[5] People who believed in traditional religions were more likely to have motivational drive and strategic planning for their actions. Perhaps not surprisingly, people who had more superstitious beliefs were less likely to control impulsive behavior.

Prayer seems to be an active way to promote replenishment. A demonstration of this point comes from an experiment where subjects engaged in personal prayer or an equivalent time in free mind-wandering thought. A subsequent self-control test revealed superior scores for those in the prayer group.[6]

Adolescents seem to have less self-control than mature adults. One study involved 1,785 young adults of different religions (Muslims, Catholics, Eastern Orthodox- and Bible-belt Christians) in different countries.[7] Young people with intrinsic religiosity (living one's faith)  were less likely to exhibit deviant behaviors, such as theft, substance use, cheating, etc. than those driven by extrinsic religiosity (using one's faith for personal advancement). The religious beneficial effect was greatest in those who had low natural levels of self-control.

Most religions make a positive social impact by teaching and requiring self-control. Just thinking about God can improve our will power. One experiment demonstrated this in a trivial way by priming subjects with a pre-test task of unscrambling sentences that contained religious thoughts. The subsequent task was to drink an unpleasant mixture of orange juice and vinegar, for which they were paid for the amount they drank. Compared to a neutral-primed control group, the religion-primed group drank twice as much of the sour juice. In another part of the experiment, investigators told participants that when the study was over they would receive monetary compensation. If the participants came back the next day, they would receive $5, but if they came back a week later, they would receive $6. Even with the small $1 difference, a greater percentage of the participants in the religious-primed group decided to wait and receive the larger amount of money than those in the neutral-primed group.[8]

Some evidence indicates that people are more motivated toward good behavior if they view God as punishing rather than a God of love. In a study at Brigham Young University, Mormon students were assigned a task to button press when they saw a picture of juice or to inhibit the press when they saw a picture of beer (which their religion forbids). A neural signal over the anterior cingulate cortex that is known to be an error indicator became smaller when subjects were reminded of God's love instead of God's punishment. The interpretation was that focusing on God's love and forgiveness made students less worried about making mistakes in the task.[9]

One of the more obvious and measurable examples of religion effects is how it can reduce pain. A common way that medical service providers assess pain is to ask a patient to rate the intensity of pain on a scale of 0 to 10. In one experiment, 24 patients, half practicing Catholics and the other half avowed atheists, had been screened to have equal baseline pain thresholds. They were then given electrical shocks while staring at different images, some religious and others not. Pain scores dropped when viewing religious images, and non-religious images had no effect. Brain scans showed that when pain was reduced, the activity level was increased in the right ventrolateral prefrontal cortex, a region that other investigators had shown was instrumental in driving top-down circuitry that inhibits pain.[10] A simple explanation is that the pain-relief is like that afforded when a dentist twists your cheek as he inserts a needle to anesthetize a tooth or a veterinarian slaps a horse's hip as he simultaneous slams a needle to inject a medication. In these cases, the signals that ordinarily cause pain are mixed with other dominant signals that limit the brain's ability to feel pain.

5.    Yoga/Meditation

Yoga is a practice that most clearly illustrates the ability of the mind to control the body. The most obvious effects of yoga meditation are on breathing, which can be dramatically slowed and made more abdominal, and the cardiovascular system, in which heart rate slows and blood pressure drops.[11]  Yoga masters can alter bodily functions in even more profound ways, such as forcing extreme sweating or lying on a bed of nails. Mindfulness meditation, wherein attention is focused on breathing or a mantra, promotes the development of attentional skills and changes neural activity related to self-control.[12

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[1] Bomyea, J., and Amir, N. (2011). The effect of an executive functioning training program on working memory capacity and intrusive thoughts. Cognitive Therapy and Research, 35(6), 529-535. doi:10.1007/s10608-011-9369-8

[2] Blair, C., & Razza, R. (2007). Relating effortful control, executive function, and false belief understanding to emerging math and literacy ability in kindergarten. Child Dev., 7(8), 2nd ser., 647-663. doi:10.1111/j.1467-8624.2007.01019.x.

[3] Penney, S. (2012). Impulse control and criminal responsibility: Lessons from neuroscience. International Journal of Law and Psychiatry, 35(2), 99-103. doi:10.1016/j.ijlp.2011.12.004

[4] Boss, L., Branson, S., Cron, S., & Kang, D. (2016). Biobehavioral examination of religious coping, psychosocialfFactors, and executive function in homebound older adults. Religions, 7(5), 42. http://dx.doi.org/10.3390/rel7050042

[5] Wain, O., & Spinella, M. (2007). Executive functions in morality, religion, and paranormal beliefs. International Journal of Neuroscience, 117(1), 135-146. doi:10.1080/00207450500534068

[6] Malte Friese, Michaela Wänke, Personal prayer buffers self-control depletion, In Journal of Experimental Social Psychology, Volume 51, 2014, Pages 56-59, ISSN 0022-1031, https://doi.org/10.1016/j.jesp.2013.11.006.

[7] Klanjšek, R., Vazsonyi, A. T., & Trejos-Castillo, E. (2012). Religious orientation, low self-control, and deviance: Muslims, Catholics, Eastern Orthodox-, and “Bible belt” Christians. Journal of Adolescence, 35(3), 671-682. doi:10.1016/j.adolescence.2011.09.003

[8] Rounding, K., Lee, A., Jacobson, J., Ji, L., Religion replenishes self-control. (2012). Psychological Science, 23(6),  635-643.

[9] Good, M., Inzlicht, M., & Larson, M. J. (2014). God will forgive: Reflecting on god's love decreases neurophysiological responses to errors. Social Cognitive and Affective Neuroscience, doi:nsu096 [pii]

[10] Wiech, K., Farias, M., Kahane, G., Shackel, N., Tiede, W., & Tracey, I. (2008). An fMRI study measuring analgesia enhanced by religion as a belief system. PAIN, 139(2), 467-476. doi: http://dx.doi.org/10.1016/j.pain.2008.07.030

[11] Olex, Stephen, Andrew Newberg, Andrew, and Figueredo, Vincent M., (2013). Meditation: Should a cardiologist care?, International Journal of Cardiology, 168(3),1805-1810,

[12] Moore, A., Gruber, T., Derose, J., & Malinowski, P. (2012). Regular, brief mindfulness meditation practice improves electrophysiological markers of attentional control. Frontiers in Human Neuroscience, 6(18), 1-15.

Lesson 14c. Memorize While You Sleep

Get enough sleep to consolidate your memories.

Did you know that your brain works while you sleep? Yes, both during dreaming and non-dreaming, your brain is consolidating memories of events in the immediately preceding day.

Most people think that the purpose of sleep is to rest the brain. But there is clear evidence that the brain is still busily at work during sleep, even when the brain is not dreaming. Decades ago, researchers demonstrated that many neurons fired just as much during sleep as during wakefulness. Some neurons were even more active during sleep.

One advantage that sleep provides for memory consolidation is that the brain doesn’t have all the distractions that occur during daytime wakefulness. Multiple-conflicting stimuli and tasks are very disruptive to memory consolidation.

The advantages offered by having fewer disruptive influences during sleep have also been confirmed in a study conducted in the brain imaging lab of Thomas Pollmacher in Munich, Germany. An auditory text stimulus was presented to sleep-deprived subjects prior to and after the onset of sleep, and imaging was performed to compare wakeful responses to sound stimuli with those during various stages of non-dreaming sleep. Brain activity during sleep was suppressed in auditory pathways and visual cortex, including other brain regions that are interconnected with the visual cortex. Suppression suggests that sleep shields the brain from the arousing effects of external stimulation that might disturb sleep. Blocking out such interference effects should facilitate memory consolidation. This study also prompted researchers to conclude that consolidation of memory occurs over many hours, at least in sleep-deprived subjects. That is to be expected, inasmuch as consolidation of memory depends on protein synthesis and physical changes in synapses.

Students often cut back on sleep to finish ever-mounting piles of homework and study. Combat soldiers are trained to function under sleep-deprived conditions. But these strategies are likely counter-productive. At my university, our Corps of Cadets used to have a tradition of rousing freshmen in the middle of the night and preventing them from sleeping. The idea was to make them tough. More likely, it just made them unable to do well in school, as I have seen many of them flunk out.  Another area where this problem has surfaced is with sleep-deprived medical residents.

Sleep loss degrades many brain functions. In one study, sleep loss degraded visual vigilance and memory for words, and time-of-day fluctuations were found in choice reaction time, logical reasoning, and word memory. Exercise also seemed to have an effect in that brain function of non-exercising subjects degraded sooner than they did for exercising subjects. So, sleep-deprived couch potatoes beware!

Researchers have found that people who stay up all night after learning and practicing a new task show little improvement in their performance. No amount of sleep on following nights can make up for the toll taken by the initial all-nighter.

Robert Stickgold and colleagues at Harvard Medical School report that people who learned a particular task did not improve their performance when tested later the same day but did improve after a night of sleep. To see whether the night of sleep actually caused the improvement, Stickgold trained 24 subjects in the same visual discrimination task, which consisted of identifying the orientation of three diagonal bars flashed for a sixtieth of a second on the lower left quadrant of a computer screen full of horizontal stripes. Half of the subjects went to sleep that night, while the other half were kept awake until the second night of the study. Both groups were allowed to sleep on the second and third nights. On the fourth day, both groups were tested on the visual discrimination task. Those who slept the first night identified the correct orientation of the diagonal bars much more rapidly than they had the first day. The other group showed no improvement, despite the two nights of catch-up sleep.

Another compelling study for the role of sleep on memory consolidation was published by Sean Drummond and his colleagues at San Diego State University and the University of California, San Diego.  They combined memory performance with magnetic resonance imaging (MRI) to study sleep deprivation effects on verbal learning of young, healthy adults. After a sleepless night, free recall fell by about half, and the brain imaging analysis showed reduced blood oxygen activity in the temporal area. However, the areas of the prefrontal cortex that had been activated during remembering after normal sleep worked even more after sleep deprivation. What's more, the bilateral parietal lobes and two additional areas in the prefrontal cortex, usually not activated after normal sleep, became active.

What about a small degree of sleep loss? A University of Pennsylvania study showed even a little sleep loss can devastate memory. People were assigned to sleep regimens of four, six, or eight hours of sleep each night for two weeks and tested periodically during the daytime for mental performance. Subjects who got four or even six hours of sleep performed as poorly on brain function tests as they did when kept from sleeping at all for three consecutive days. So, short-changing your sleep each night by an hour or so builds up a sleep debt that affects attention and working memory. In the study, performance decline was cumulative. An interesting aside from the study was that none of the 48 people in the study realized that their mental performance had deteriorated from the mild sleep loss. As a college professor, I wonder about the performance loss going on in students who short-change their sleep for months at a time.

There are also studies revealing lack of sleep BEFORE learning interferes with memory. Formally, this is called "proactive interference," because it occurs in advance. The cause may relate to what was just explained: a sleepy brain doesn’t think effectively.

In another study, 28 healthy young adults were divided into two groups. On the first day, one group was kept awake for 35 straight hours. Participants in the other group spent a normal sleep night at home. At 6 PM of the next day, all subjects watched a slide show of 150 slides of landscapes, objects, and people who weren't celebrities. All subjects then were sent home to have a normal night's sleep. The next evening all subjects took a pop quiz on the slides, which were randomly mixed with 75 new slides. The test was for subjects to recognize whether they had seen each slide before.

Those subjects who had been sleep deprived on the first night scored the lowest, even though they later had a night to catch up on lost sleep. The upshot of it all is that lack of sleep is bad for remembering, whether the sleep loss occurs before or after learning events. For those who wonder why humans need to sleep, one obvious benefit is to enhance learning.

Need to learn something quickly? Take a nap. Daytime naps are said to rejuvenate energy and lower stress. Now there is evidence naps speed up consolidation of memories.

Matthew Walker reports experiments showing nap enhancement of memory. In his study, 39 young adults were divided into two groups. At noon, all the participants took part in a memory exercise that required them to remember faces and link them with names. Then the subjects took part in another memory exercise at 6 p.m., after 20 subjects had napped for 100 minutes during the break. Those who remained awake performed about 10 percent worse on the tests than those who napped. Students take note: 10% is often the difference between an A and a B.

 

Sleep Sources

Drumond, Sean, Brown, Gregory, G., Gillin, J. Chrisstian, Stricker, John. L. (2000). Altered brain response to verbal learning following sleep deprivation. Nature 403(6770):655-7. DOI: 10.1038/35001068

Stickgold, R., James, L, and Hobson, J. (2000) Nature Neuroscience.  3 (12), 1237-1238. DOI:10.1038/81756

Van Dongen, H.P.A., Rogers, N.L. & Dinges, D.F. Sleep debt: Theoretical and empirical issues. Sleep Biol. Rhythms 1, 5–13 (2003). https://doi.org/10.1046/j.1446-9235.2003.00006.x

Walker, Matthew (2010). American Association for the Advancement of Science annual meeting presentation, San Diego, Feb. 21, 2010.

 

This concludes our lessons in this series on Learning How to Learn.

I believe and hope that you all will become more effective life-long learners.

 

Lifestyle Matters. Lesson 14b. Exercise

 

Be healthy. Be smart.

Exercise is not only good for the body; it is good for the brain.  The idea that exercise might benefit memory originally came from animal research revealing exercise increases learning and memory capability, presumably because exercise stimulates the birth of new nerve cells in the hippocampus, the part of the brain that is crucial for forming long-term memory. I have posted many articles on the benefits of exercise for the brain  at this blog site (type “exercise” into the search field).

It is now clear that exercise benefits memory capability in humans too, both old and young. In addition, the state of exercise is tied to memory; that is, state-dependent memory can be demonstrated with exercise. For example, in a study of humans exercising on a bicycle, word lists learned during the exercise were recalled best during another exercise episode, while words learned not riding on a bike were recalled best under that same condition. State-dependent learning has been demonstrated in other contexts too, such as with alcohol and with school-room environments.

Even when I was a kid, which was long before the whole notion of aerobic exercise, people said that being physically active could help you perform better in school. But this was mostly anecdotal, with very little research evidence. Now there is much solid evidence. Sadly, it may have come too late. Many schools have done away with or minimize physical education. Many girls think it’s not cool to sweat.

Charles Hillman and colleagues at the University of Illinois recently reported a study on the effects of exercise on cognitive function of 20 children aged 9 to 10. They administered some stimulus discrimination tests and academic tests for reading, spelling and math. On one day, students were tested following a 20-minute resting period; on another day, students walked on a treadmill before testing. The exercise consisted of 20 minutes of treadmill exercise at 60% of estimated maximum heart rate. Mental function was then tested once the heart rate returned to within 10% of pre-exercise levels. Results indicated improved performance on the tests following aerobic exercise relative to the resting session. Tests of brain responses to stimuli suggested the difference was attributable to improved attentiveness after just this one bout of exercise.

Note this is just from a single aerobic exercise experience. How can that be beneficial? The most obvious explanation is that exercise generates more blood supply to the brain, but I don't know that this has been documented. Actually, what is known is that exercise diverts blood to the muscles. The generally accepted view is that the body tightly regulates blood flow to the brain and that the brain always gets what it needs.

A more likely explanation is that single bouts of exercise relieve anxiety and stress, which are known to disrupt attentiveness and learning. Maybe the repetitive discipline of exercises like treadmill-walking help entrain the brain into a more attentive mode, akin perhaps to meditation. We need a study that compares treadmill walking with a different kind of exercise regimen (like a vigorous and competitive basketball game, for example).

As for what goes on in a typical school recess, I doubt that such activities as gossiping, text messaging, or whatever else goes on these days with kids at recess markedly interfere with learning.

There is also the possibility a continuing aerobic exercise program could produce long-lasting beneficial effects in young children. My own prejudice is that schools and parents ought to get serious about requiring aerobic exercise programs. It should not only improve the quality of school work but also help combat the epidemic of obesity and diabetes. One caveat: excessive running to achieve aerobic levels of exercise may not be advisable in children. My own experience with jogging, for example, might have been great for my heart and brain, but I now have two artificial knees and an artificial hip joint to show for it.

Here is another caveat you may have thought about: If exercise is so good for academic performance, why do varsity athletes generally make poorer grades than their classmates? Well, there are many other factors, of course. One prevailing attitude among athletes is that academics are less important to them than their sport. Athletes tend to devote their time and energy to their sport, not school work. They also have more incentive to focus on their sport. Students idolize athletic stars. But students who make all As are not considered heroes; they are often considered nerds or otherwise abnormal. What should be normal is to exercise both body and brain. 

Sources, Exercise

Hillman, C. H., Pontifex, M. B., Raine, L. B.,  Castelli,, D. M., Hall, E. E., and Kramer, A.F. (2009). The effect of acute treadmill walking on cognitive control and academic achievement preadolescent children, Neuroscience, 159 (3), 1044-1054, https://doi.org/10.1016/j.neuroscience.2009.01.057.

Miles, Christopher, and Hardman, Elinoir. (2010). State-dependent memory produced by aerobic exercise. Ergonomics. 41(1), doi.org/10.1080/001401398187297

 

 

Lesson 14a. Lifestyle Matters: Effects of Stress

School is stressful. Students also commonly must deal with emotions arising from boy-girl problems, over-bearing parent problems, bullies, worries about school, frustrated attempts to be popular, and their future. College students have enormous adjustments to make in the transition from leaving home and the cloistered environment they were used to in high school. Older adults returning to school have to cope with paying the costs, finding time for the family, and for the job.

The aspects of lifestyle that have the greatest direct effect on learning deal with stress, exercise, and sleep. This post explores stress.

Stress

 All learning at some point involves stress. Acute stress, which releases adrenalin, can be a good thing. It pumps you up and promotes focused attention. However, chronic stress impairs learning. When students struggle to improve, chronic stress ensues and creates a vicious cycle in which the stress impairs performance, which produces still more stress.

I have written numerous science-based posts on the bad effects of chronic stress on the brain. To review these and type “stress” into the search field of this blog.

Scientists have long known that chronic stress is bad for your brain. Adolescence seems to be an especially vulnerable time. Not only is the adolescent brain still being built, the brain is being re-built during the teen years.

Human imaging studies show the cerebral cortex shrinks during adolescence. In a recent study of "adolescent" rats, researchers found that the cortex shrinks in both males and females, and there is a loss of neurons in the ventral prefrontal cortex, the part of the brain humans use to make rational decisions and do higher-level thinking. More loss occurred in females than in males.

Until now, the reason for brain tissue loss has not been clear, but we may be able to explain it by considering the stresses that afflict teenagers, who routinely endure peer dismissiveness and bullying. Numerous animal studies show that stress impairs brain function and memory. Even single bullying exposures can be damaging.

Similar results have been reported in multiple humans studies. Here is a very real example of stress-related memory impairment from human bullying in schools that few may realize. In the study, young healthy men were tested for their ability to recall lists of 10 positive, 10 neutral, and 10 negative words. The men were given two minutes to learn the lists and were then tested immediately. Thirty minutes later they were given a psychosocial stress which included a fictitious job interview in front of live interviewers and counting backwards in steps of 17 in front of judges. Control groups did a five-minute speech and did the same counting, but not in the presence of judges. The next day, subjects were tested again (delayed recall) 10 minutes after cortisol injection. Other psychological tests were administered and the amount of cortisol in the saliva was measured at several key points in time.

The stressed group had elevated cortisol levels even though the stress was mild. Recall of both negative and positive emotionally arousing words was impaired, but there was no effect with neutral words. These effects could not be attributed to decreased attention or working memory span, which memory tests showed were not affected by the stress. Providing cues for recall eliminated signs of the stress effect on emotionally charged words.

So, this study shows recall of emotionally charged information can be impaired under stressed conditions. Imagine how great the deleterious effect of stress could be in situations where there is real stress, as in witnessing car accidents, crimes, or dangerous situations in which recalling what happened could be very important. Studies like this are consistent with many real-life observations with eye-witness accounts, where what is remembered may well be false.

The most obvious stressor for students comes from examinations. “Test anxiety” causes students to choke, typically failing to recall information they know they know, but just can’t dredge up under stressful test conditions.

A couple of studies have shown that test scores rise if anxious students are allowed to write about their test worries for 10 minutes just before a test. It also works to write down attributes of successful problem solving just before a test.

Why does this writing alleviate test anxiety? One study showed that such writing increased student engagement in the test. That is, students who were anxious were distracted by their anxiety and did not fully engage in solving the problems in the test.

Such writing before an exam is only beneficial for students who suffer from test anxiety. Other students don’t need this, and may in fact do worse by such a distraction. The best way to deal with choking on tests is to: 1) thoroughly know and understand the material being tested, and 2) develop long-term confidence by a string of test successes. If you truly “know your stuff” and believe in your ability as a student, there is no justification for test anxiety.

 Next Lesson: 14b. Lifestyle Matters: Exercise

Stress Sources:

Merz, Christian (2010). Stress impairs retrieval of socially relevant information. Behavioral Neuroscience. 124 (2), 288-293.

Newcomer, J. W., Selke, G., Melson, A. K., Hershey, T., Craft, S., Richards, K., et al. (1999). Decreased memory performance in healthy humans induced by stress-level cortisol treatment. Archives of General Psychiatry, 56, 527–533.

Vogel, Susanne (2016). Learning and memory under stress: implications for the classroom. Science of Learning 1(1), 16011. DOI: 10.1038/npjscilearn.2016.11

Young, A. H., Sahakian, B. J., Robbins, T. W., & Cowen, P. J. (1999). The effects of chronic administration of hydrocortisone on cognitive function in normal male volunteers. Psychopharmacology (Berl), 145, 260-266.

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