Hemispheric asymmetries in motivation neurally dissociate self-description processes.

When people describe themselves by responding to personality questionnaires, typically they endorse some items and reject others. Further, most people endorse likable traits and reject unlikeable traits. In one case, people use previously stored information about themselves to judge that a particular trait--usually likable--describes them well, and in the other, they use previously stored information to judge that a particular trait--usually unlikeable--does not describe them well. Here we report evidence that these processes are neurally dissociable, with the former benefiting from engaging left-hemisphere processes and the latter benefiting from engaging right-hemisphere processes. Hemispheric asymmetries in self-description are not unidirectional and do not differ across different personality traits, but do differ between endorsing likable items and rejecting unlikeable items. Thus, we are not dispassionate observers of ourselves. Dissociable, basic motivational processes are involved in the neural architecture underlying self-description.