Tracking cognitions or emotions (often both) refers to a person recording when they have certain thoughts or feelings. The person might note every time they experience a given thought or specific feeling whenever it comes up, or alternatively simply keep a diary of any notable thoughts or feeling at pre-determined times. Often, this also includes noting what triggered or occured before or alongside these thoughts and emotions.
Many therapuetic approaches utilize this tool, even if only for brief periods, to help a system, clinician, or patient better understand the patterns around their thoughts and feelings. Often, this data is integrated into additional behavior change approaches, like behavioral activation or implementation intentions.