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Brain adaptations to stressful childhood environments

Childhood_AdversityImagine a boy who grew up never knowing where his next meal would come from or when it would come. Now imagine a boy who had everything handed to him.

Who do you predict will have higher cognitive functioning, which consists of processes such as pattern recognition, memory, attention, and language? If you guessed the second boy, you are correct. Childhood adversity has been shown to negatively impact important cognitive functions, such as language development, sustained attention, and memory, which result in poor reading and math abilities, lower IQs and academic achievement (Fernald, Weber, Galasso & Ratsifandrihamanana, 2011). To figure out why this is the case, we must consider an important characteristic of our brains—their plasticity, or ability to change!

So, why is plasticity an important characteristic of our brains? What are the advantages of our cognitive functioning being susceptible to change? Adaptation! Adaptation got Mittal, Griskevicius, Simpson, Sung, and Young (2015) thinking about the universality of the negative impact on cognitive functions that childhood adversity has been shown to have. If the brains of those who grow up in stressful environments can be negatively affected by their experiences shouldn’t that mean that they could also be positively affected? The work of Mittal et al. (2015) tells us the answer!

Because these researchers weren’t buying into the fact that childhood adversity could only negatively affect cognitive functioning, in Cognitive Adaptations to Stressful Environments: When Childhood Adversity Enhances Adult Executive Function they sought to find out if harshness and unpredictability during childhood affected performance on two tasks that measure an individual’s control over cognitive processes, which is known as executive function. Two important executive function processes are inhibition and shifting (if you are interested in learning more about other factors that effect effective functioning, see this post about on sleep deprivation or this one about aging and water exercise).

Inhibition is the process of ignoring irrelevant or competing information. Think about a path you walk almost every day on campus; maybe it’s from Davis to Bobs for lunch or your room in AMS to Lovejoy. Do you ever show up to class unable to remember any details from your walk and think how did I even get here? This is because this has become a habit, and this walk requires little of your effort or attention. Now think about a time you had to do something unusual before class—maybe pick up a package in the Spa or stop at a friend’s room to pick up a book. You probably have to remind yourself a couple of times on your walk to take a different path than you are used to so you don’t just go on autopilot and end up in class. You have to deliberately override or suppress your tendency to walk the normal path you take every morning. This is how inhibition in cognitive psychology works—you have to override automatic cognitive processes (those that require little attention and effort and occur outside your awareness). To learn more about inhibition in cognitive psychology visit this post about The Stroop Task, a classic measure of inhibition.

Shifting is the efficient switch from one task to another. You probably do some shifting often every time you do your homework. You’re diligently working on a paper or reading a textbook chapter and decide you can reward yourself with a quick scroll through Instagram once you finish a paragraph. Then when you go back to reading you have to re-engage and re-read the paragraph you just finished because the next one is making no sense (to learn more about homework and cellphones read this post).

These two important cognitive functions are the ones considered by Mittal et al. (2015). If you were to participate in their study you would perform both an inhibition and a shifting task. You would be unknowingly assigned to either the control or uncertain condition. Having two conditions helps determine if the results are context specific (only emerge when the context is consistent with that of the participants’ childhood). In either condition you would read what you would think was an article from the New York Times. If you were in the control condition

Screen Shot 2015-11-24 at 10.36.27 AMyou Screen Shot 2015-11-24 at 10.34.52 AMwould read an article about a person searching for their lost keys. In the uncertainty condition you would read an article entitled Tough Times Ahead: The New Economics of the 21st Century, which would be about economic uncertainty.


Then, you would perform the inhibition task, which is called the antisaccade task. In this task you would be rapidly shown a + in the center of the screen, then BAM! a bright flash would appear on one side of the screen, followed by a block arrow on the opposite side of the screen from theScreen Shot 2015-11-24 at 10.37.26 AM flash, and finally a box would cover the arrow. You would then be asked to indicate which way the arrow was pointing (left, right, up, or down). The more times you correctly identified what way the arrow was pointing, the better your performance would have been. To be successful on this task, you would have had to inhibit your attention from being captured by the flash, an exogenous cue (a salient cue that reflexively captures your attention), and would have had to instead intentionally directed your attention to the arrow.


To test your shifting ability, the color-shape task would be used. In this task, the word “color” or “shape” would be displayed at the top of the screen. The word would indicate whether you would be required to categorize a color or shape. Next, a red or green shape, either a triangle or a circle, would appear on the screen. You would be tasked with quickly and accurately categorizing

Screen Shot 2015-11-23 at 9.34.44 PM the image according to the word at the top of the screen. For example, if the word was color and a green circle was displayed, you would be correct if you answered “green”. In repeat trials the same categorization word would be used on two or more consecutive trials (example—trial 1: shape, trial 2: shape). In switch trials, you would be prompted to classify items according to the word not used in the previous trial (example—trial 1: shape, trial 2: color). Half of the trials would be repeat and half would be switch. Your performance would be determined by subtracting your response time to switch trials from your response time to non-switch, which is known as “switch cost”. Lower switch costs signify that you are good at shifting, as you can efficiently switch between changing situations, while higher switch costs signify you are poor at shifting, as you get stuck on one category and cannot rapidly switch to a different situation.

Finally, you would be asked some questions to determine what kind of childhood you had. If you had low socioeconomic status as a child you would be classified as having had a harsh childhood. If you grew up in homes where changes were common you would be classified as having had an unpredictable childhood.

The results of this experiment showed that having an adverse childhood can enhance some aspects of cognitive functioning. In the uncertainty condition, individuals who experienced unpredictable childhoods performed worse on the inhibition task but performed better on a shifting task as compared to individuals who did not experience unpredictable childhoods. However, the performance of individuals reared in harsh environments was not different from that of individuals raised in non-harsh environments. These results make sense when we think about some of the skills that are necessary to survive in unpredictable environments. If you were offered $10 now or $20 in a week, which would you chose? If you grew up in an unpredictable environment you would have learned that the future is uncertain and that being opportunistic is important as it allows you to take advantage of short-term opportunities before they are gone, so you would probably elect to take the $10 now. However, if you had a less unpredictable childhood you would control your impulse to take the $10 immediately and accept the offer to take $20 later. Inhibition is beneficial in stable environments because it aids in the achievement of long-term goals. On the contrary, shifting is beneficial in harsh environments, as being able to switch between tasks efficiently is necessary to take advantage of fleeting opportunities and adjust to changes in a harsh, unstable environments. Living in an unpredictable environment, you are constantly adjusting to change: you may have to adjust to new schedules often as your parents change jobs, or you may have to adjust to new rules and people if it is necessary for you to live with a different family member every few weeks. Being able to efficiently adjust to changing circumstances is important for those who live in unpredictable environments.

Because the results of the experiment were so novel, the experimenters tried the experiment again. The same results were found for the inhibition task; however, the results differed for the shifting task. Attributing this to the small sample size, experimenters replicated the study once more with a larger sample and found the same results as they did in the first experiment.

In a final study, researchers used a unique sample. First, the participants were older and more economically disadvantaged than the university students used in the other studies. old-manAdditionally, experimenters had data from many points in the participants’ lives, so they were very accurately able to classify participants’ childhood experience (in the other study this was determined through a self-report questionnaire). This study only measured shifting, using the same procedure as the previous studies. Because there was a wide range in reading abilities the context manipulation was different in this study; the news story was presented in a slideshow. The uncertain participants viewed a slideshow on increasing economic uncertainty, while participants in the control condition viewed images and brief descriptions of nature scenes. The results of this study were the same as those from the first and third experiment: in conditions of uncertainty, the more unpredictable participants’ childhoods were, the better they performed on the shifting task.

This research specifically changes the way we had previously looked at childhood adversity and its affect on cognitive functioning: from simply impairing it to adaptively shaping it. More broadly, it is important because it provides additional evidence to the adaptive nature of our brain. Our brains ability to change depending on our given environment allows us to benefit as much as possible in our given environment.


Fernald, L.C.H., Weber, A., Galasso, E., & Ratsifandrihamanana, L. (2011). Socioeconomic gradients and child development in income population: evidence from Madagascar. Developmental Science, 14(4), 832-847.

Mittal, C., Griskevicius, V., Simpson, J.A., Sung, S., & Young, E.S. (2015). Cognitive adaptations to stressful environments: When childhood adversity enhances adult executive function. Journal of Personality and Social Psychology, 109(4), 604-621.

The full article can be found here.

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