From Kermit Rose:

Re: A surprising new way to discourage risky behaviors? (Aug. 25): “De­ci­sions are not only based on risks and ben­e­fits, but al­so the ident­ity that a giv­en choice com­mu­ni­cates to oth­ers,” Berger and Rand wrote. Thus “shift­ing per­cep­tions of the ident­ity associa­ted with a risky be­hav­ior can help make bet­ter health a real­ity.” ...

How do these researchers know that the change in the student’s behavior is not because of some other reason, like not wanting to be predictable?