Young adult cannabis users showed increased caudate activation when receiving peer information and took longer to make decisions that went against the group, suggesting heightened neural sensitivity to social influence.
Read this if you want to understand the neuroscience behind social influence and cannabis use in young adults.
Cannabis users took longer to disagree with peers and showed greater caudate response to social cues
What the researchers found
This companion study to RTHC-01164 used a slightly different social influence paradigm with 20 cannabis-using young adults and 23 controls. Participants made perceptual choices after seeing what their peers chose.
Behaviorally, cannabis users and controls followed or opposed the group at similar rates. But cannabis users showed significantly longer reaction times when deciding to go against the group, suggesting they had to exert more cognitive effort to resist conformity.
The brain imaging revealed that cannabis users had significantly greater caudate activation when presented with peer information compared to controls. Across both groups, caudate activation correlated with self-reported susceptibility to influence. The longer reaction times when opposing the group were associated with greater frontal brain activation.
Why it matters
This study complements the findings of RTHC-01164 by showing that cannabis users are not simply more conformist, but rather that processing social information appears to require more neural resources for them. The reaction time data suggests that going against peers is cognitively more effortful for cannabis users, even when they ultimately make independent choices.
The numbers in context
Twenty cannabis users vs. 23 controls. No behavioral difference in conformity rates, but cannabis users had slower reaction times when opposing group choices. Greater caudate activation to peer information in cannabis users. Caudate activation correlated with self-reported susceptibility to influence across groups.
How the study worked
Cross-sectional fMRI study comparing 20 marijuana-using young adults with 23 controls. Participants viewed photographs of peers and their choices in a perceptual decision task during functional MRI scanning. Reaction times and brain activation were analyzed in relation to social conformity and resistance.
What this study cannot tell us
Cross-sectional design cannot establish causality. The small sample size limits statistical power. Peers were unknown to participants, which may reduce the ecological validity of the social influence manipulation. Self-reported cannabis use.
How to read the evidence
Well-designed fMRI study with appropriate sample size and controls, but cross-sectional design and small groups limit generalizability.
When this study was published
Published in 2016. This line of research on social neuroscience and substance use continues to develop.
The bigger picture
Together with RTHC-01164, these findings suggest that cannabis use is associated with a broader pattern of heightened neural sensitivity to social information. This goes beyond simple peer pressure and touches on fundamental differences in how cannabis users process social cues and make decisions in social contexts.
Questions still open
- Is the heightened neural response to social information a trait that predisposes people to cannabis use, or does cannabis use change the brain's social processing? Would this heightened sensitivity be seen with other social tasks beyond perceptual decisions?
Common questions
Are cannabis users more easily influenced by peers?
How does this relate to cannabis prevention?
Read the original research
Neural mechanisms of sensitivity to peer information in young adult cannabis users.
Cognitive, affective & behavioral neuroscience, 16(4), 646-61
Citation
Gilman, Jodi M; Schuster, Randi M; Curran, Max T; Calderon, Vanessa; van der Kouwe, Andre; Evins, A Eden. (2016). Neural mechanisms of sensitivity to peer information in young adult cannabis users.. Cognitive, affective & behavioral neuroscience, 16(4), 646-61. https://doi.org/10.3758/s13415-016-0421-8
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