Scans of an individual’s brain activity are emerging as powerful predictive tools, thanks to the Human Connectome Project  (HCP), an initiative of the National Institutes of Health. Such individual differences were often discarded as “noise” – uninterpretable apart from group data. Now, recently reported studies based on HCP neuroimaging and psychological data show that individual differences in brain connectivity can reliably predict a person’s behavior.  Such scans might someday help clinicians personalize diagnosis and treatment of mental disorders, say researchers.