It is common to talk about how
the teenage years are a time of risky behavior.
And, when we talk about why teens engage in risky behavior, there is a
tendency to focus on the development of the frontal lobes. We know that there are mechanisms that involve
the frontal lobes of the brain that stop behavior that has been engaged. In Smart Change, I call these
mechanisms the Stop System. The frontal
lobes do not mature fully until early adulthood, and so that is part of the
reason why teens do risky things.
If it was just that the Stop
System hasn’t matured yet, then even young children should engage in lots of
risky behavior. Instead, there is
another component. Adolescents also engage
lots of behaviors that they perceive to be rewarding. I call the mechanisms that drive people
toward behaviors the Go System.
This view suggests that
adolescents have a perfect storm of a Go System that is driven to pursue
rewards despite potential risks and a Stop System that is not capable of
stopping a behavior that is risky.
An interesting paper in the
November, 2014 issue of Psychological Science by Zachary Roper, Shaun Vecera, and Jatin
Vaidya provides some evidence for this view of adolescent risky behavior.
These researchers suggest that if
adolescents are drawn toward rewards, then they should persist in paying
attention to rewarding items in the environment, even when they are no longer
rewarding.
To test this possibility, 40
teens (ranging in age from 13-16) and 40 adults (with an average age of 27)
were run in a study. In the first part
of the study, participants saw a number of colored circles on a computer
screen. Inside of each circle was a
line. There was always one red or green
circle on the screen, and the rest were other colors. Participants had to press one of two buttons
to indicate whether the line inside the target circle was horizontal or
vertical. When they responded correctly,
they were rewarded. For each
participant, one color was generally associated with a larger reward (10 cents)
than the other (2 cents). So, for a
particular participant, the red circle might generally lead to a 10 cent reward
and the green circle might lead to a 2 cent reward.
After doing 240 trials like this,
the task was changed. Now, participants
did another 240 trials in which they had to find a blue diamond and report the
orientation of the line inside that shape.
The rest of the objects on the screen during these test trials (which
are called distractor items) were
colored circles. On some trials, one of
those distractor circles was a red or green, which had been associated with a
reward in the first part of the study.
The key question was whether the
amount of time it took participants to respond correctly on the test trials was
affected by the presence of circles that had been rewarded in the first part of
the study. If it takes longer for
participants to respond in the presence of a distractor that had been rewarded
in the past, it suggests that distractor is attracting attention from the real
goal of the task.
Adults are not strongly affected
by the initial training. In the first
group of test trials, they are a little slower at responding when one of the
distractors had been rewarded in the first group of trials. After about 60 trials, though, adults are no
longer affected by what had been rewarded before. That is, the Go System no longer drives
adults toward old rewards.
The teens act quite
differently. They are much slower to
respond when one of the distracting circles had been rewarded in the past. They are slowest when the distractor was color
that got the large reward. They are
fastest when none of the distractors had been rewarded. The circle that got the small reward came out
in between. This effect persisted over
the entire set of 240 test trials.
Finally, the effect was strongest
in the 13- and 14-year-olds who were tested.
They were most captivated by the circles that had been rewarded
before. The 15- and 16-year olds were
also a bit slower when faced with a circle that had been rewarded before, but
not as much as the younger teens.
This suggests that the risky
behavior we see in teens has two sources.
First, the Go System of teens gets directed toward things that have been
rewarded in the past. It is hard for
teens to dampen this activity of the Go System.
Then, on top of that, the Stop System has trouble overcoming the
direction of the Go System, so that teens continue to act on the impulse to do
what had been rewarded on the past.
Ultimately, this validates the
importance of using the environment to help teens protect themselves. It is just hard for teens to overcome strong
temptations. Perhaps the best way to
help teens to avoid risky behavior is to remove the most significant risks from
the environment. While teens have to
learn to say no to activities they should not perform, there is no reason for
them to have to overcome the full strength of their Go Systems.
