WE’VE all been there: you feel especially smart and funny when talking to a particular person, only to feel hopelessly unintelligent and inarticulate in the presence of another.

You’re not imagining things. Experiments show that when people report feeling comfortable with a conversational partner, they are judged by those partners and by observers as actually being more witty.

It’s just one example of the powerful influence that social factors can have on intelligence. As parents, teachers and students settle into the school year, this work should prompt us to think about intelligence not as a “lump of something that’s in our heads,” as the psychologist Joshua Aronson puts it, but as “a transaction among people.”

You become like the people you most spend your time with.