What Were You Thinking!?: Teenagers show different processing of positive and negative consequences across adolescence

Anyone who has spent time around teenagers knows they don’t always consider the full consequences of their actions. Just consider the dozens of YouTube videos involving falling dressers or fireworks illustrating this fact. Adolescents are typically more focused on the potential benefits of a choice (it could go viral!), with little regard for the negatives (an emergency room visit at 2 am). It is easy, and completely understandable, to be frustrated with this sort of behavior. However, we can make more sense of this behavior–and perhaps gain more patience–when we consider findings on how the brain processes consequences and how this changes throughout adolescence.  We might even come to appreciate this behavior as a normal and healthy part of adolescent development.

Think of a simple choice we make every day: what to get for dinner. This choice is deceptively complex, forcing us to consider whether we want to make dinner, go out, get take out, or delivery. With each of these choices there are a variety of costs and benefits, such as traffic, ease, and money. It should come as no surprise then that even when making “simple” choices like this, many regions of your brain are active and communicating with each other in complex patterns. Within this network, there are two distinct brain regions that separately process positive consequences (or gains) and negative consequences (or losses).

…adolescents are more reactive to positive outcomes than adults.

Gains are primarily processed in the striatum. The striatum is a deep, centrally located brain region that appears striped. Its striped appearance is due to alternating bands of grey and white matter. This appearance also hints at the complexity of the striatum, which consists of many smaller structures (entire careers have been spent studying these!). Research has shown that that it becomes more active the greater a potential gain, and, furthermore, that adolescents specifically show greater striatal activity than adults when shown the same reward. This can be interpreted to mean that adolescents are more reactive to positive outcomes than adults. 

One theory involves specialized brain cells, the spindle neuron, which has a high density in the anterior insula.

Losses, on the other hand, are processed in the anterior insula. This structure resides in the deep folds on the sides of your brain and is implicated in all kinds of cognitive processes. Why this region is involved in such a wide variety of cognitive abilities? One theory involves a specialized brain cell, the spindle neuron (AKA “von Economo neuron”), which has a high density in the anterior insula. These types of neurons are only seen in humans and great apes, and may be specialized for more complex cognitive abilities. While this structure has been shown to be associated with losses, there has been very little work on how loss processing changes across adolescence.

To fill in this gap, developmental neuroscientists at Harvard recently conducted a study comparing the activation of the striatum and anterior insula across adolescence. To do this, they asked adolescents to complete a decision-making task while in an fMRI scanner. For the task, they were shown the consequences of getting a question correct or incorrect. There were two sets of consequences: high stakes ($1.00 gain if correct/.50 loss if incorrect) and low stakes ($ .20 gain if correct/ $.10 loss if incorrect). They then were shown a card with a question mark and had to guess whether the card was greater or less than 5 (the cards ranged from 1 to 9, excluding 5). Actual performance in the task wasn’t important– what was vital was how the consequences they saw beforehand affected brain activity.

These consequences allowed them not only to directly compare brain activity for gain and losses, but to also see how the high or low stakes of gains and losses affected activity. Lastly, looking at activity in a sample of adolescents from 13 to 20 (yes, adolescence goes to 20!)[footnote 1] allowed them to see how this activation is altered across adolescent development, comparing ages in greater detail than done before. 

Taken together, these results show us what many parents already know: early and mid-adolescents are particularly vulnerable when weighing consequences.

Intriguingly, they found no direct effects of age on the activity of either region for all gains and losses. What they did find, however, might be more interesting and informative. The striatum showed heightened activation during large stakes compared with the small stake in early adolescence. Furthermore, this difference becomes smaller over the course of adolescence, activation going down in a straight line as they get older. The anterior insula shows a completely distinct developmental trajectory, resembling a u. It shows particularly low levels of activity during mid-adolescence when viewing large versus small losses, with larger differences in early and later adolescence.

Taken together, these results show us what many parents already know: early and mid-adolescents are particularly vulnerable when weighing consequences. While it is easy to see this as a bad thing, having a larger focus on positive outcomes means you are more likely to just go for it. This leads to adolescents who feel free to explore and learn, whether that learning involves the dangers of playing with fireworks or a constructive new hobby (or both). Thus, exploration may be critical for normal development during adolescence. Experience can be the best teacher!

Knowing this, we might be more patient even when teenagers in our lives show a level of recklessness to rival a Beavis and Butthead cartoon. If nothing else, we’ll hopefully learn to identify those risky moments when we need to watch teenagers closely.

Illustration by Kayleen Schreiber

Footnote 1: The World Health Organization defines adolescence as a developmental period from ages 10 to 19, but this varies greatly by culture. Neurobiologically, it is characterized as a period where many sensory areas of the brain are fully developed, but many areas involved in cognitive processing are still undergoing radical change, which has been shown to take place until the age of 22 in some people.

Jack-Morgan Mizell

Jack-Morgan is a graduate student in the Cognition & Neural Systems Psychology program at the University of Arizona, working in the Neuroscience of Reinforcement Learning Lab of Dr. Robert Wilson.