Enhancing peer pressure with Ritalin.

Oct 24 2012 Published by under Behavioral Neuro

We often view peer pressure as a bad thing, you know, the kind of thing that makes a 10 year old smoke a cigarette or something. But peer pressure, or the more scientific term of social conformity, is not actually inherently a bad thing. Being sensitive to other people's opinions can help us get along as social beings, showing us the value of things (everyone else says that Gucci bag is worth a lot, so it must be), and allowing us to pass on those values within a group. It also allows us to understand what other people want, which can help us work within the motivations of others.

While, yes, this does lead to things like subprime mortgage crises, it also is pretty essential for effective social interaction. Social learning which leads to conformity, heading more toward what is considered the 'norm' can be used to gain reputation within a group or receive other positive social effects.

And social learning, and the social agreement that comes from conformity, is pretty important in humans. It's so important that it recruits the reinforcement and reward circuitry in the brain. Social agreement feels good and actives the reinforcement related areas, which are heavily reliant on dopamine signaling. Dopamine is a neurotransmitter which is often associated with the rewarding and reinforcing properties of things like cocaine, but it's also associated with something called salience, how important or relevant something is to us. When something is rewarding, it is highly, highly salient. And when something is important, it is also salient.

So the question that the authors of this study asked was this: do dopamine increases, which might increase salience, also increase our social conformity?

Campbell-Meiklejohn. "Modulation of Social Influence by Methylphenidate" Neuropsychopharmacology, 2012.

To look at this, the authors took 38 subjects (all women, which is interesting. While I'm pleased that they used women, I wonder if there are sex differences to the effect), and gave half of them Ritalin, and half placebo. Ritalin, the chemical methylphenidate, is a drug usually used for treatment of attention deficit hyperactivity disorder. It blocks the reuptake of dopamine and norepinephrine in the synapse, increasing the amount present. In people with ADHD, this can increase attention and focus, but dopamine also increases salience, and that's what the authors were focusing on.

This is also important because people with ADHD tend to show deficits in social performance, often resulting in things like social conflict and difficulty in social situations. This is usually improved when they are on a medication like Ritalin. Is this because the dopamine increase from Ritalin helps them socially conform?

So the authors gave healthy women Ritalin, and then gave the women tasks. First, they gave them a social conformity task. The participants saw pictures of same sex faces, of average attractiveness and smiling averagely (is that even a word?). They were asked to rate on a scale how trustworthy they thought the person would be. After they rated, they saw an average score of how OTHER people rated the trustworthiness of the individual. Then they moved on to the next person.

Then they did a working memory task called the 2 back task. This task requires that you remember a letter, and whether it is the same as the one that you saw two letters ago. There was no difference here between the drug treated groups.

And then, SURPRISE! The participants had to rate the faces again, this time not being told what the average rating was. This allowed the authors to see how the ratings changed once people knew what the "social norm" was.

This is what they got. You can see on the left and on the right that people on Ritalin (methylphenidate in the figure) were more likely to conform more on the second try, they showed larger changes in value than those on placebo. But they only showed this when their differences had previously been moderate. When they had previously held a very different view, both placebo and Ritalin groups changed their ratings, but for the moderate difference, the Ritalin group showed MORE of a social influence.

The authors hypothesize that this is because Ritalin, by increasing dopamine, increases the salience of the social cues the participants were exposed to, making the differences in ratings more important to those on Ritalin, and making them more likely to change their view to fit the social norm. This seems like something that would make sense. While dopamine itself shouldn't make you a social conformer, increasing dopamine might make the social dues more salient. The authors hypothesize that this might be what helps people with ADHD do better socially when on medication, though they (and I) caution that the study was only done in healthy patients, and the effects on ADHD patients have not been determined yet. It would be interesting to see if the effects are different than those in healthy patients.

But the study does show us something interesting: social norms have a lot of salience, and when you increase the salience, you increase the peer pressure. Is it a good or a bad thing? That remains to be seen.

Campbell-Meiklejohn DK, Simonsen A, Jensen M, Wohlert V, Gjerløff T, Scheel-Kruger J, Møller A, Frith CD, & Roepstorff A (2012). Modulation of social influence by methylphenidate. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 37 (6), 1517-25 PMID: 22318197

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