A cultural probe, also known as a diary study, is a type of ethnography where participants self-report their behavior. They periodically record their actions and thoughts about the activities being studied.

For example, one study carried out by a design agency attempted to understand why users make repeat purchases from brands. Participants were sent a diary kit with specific questions that encouraged them to write about their daily life. This included themes like relationships, routines, and expectations that were relevant to the main goals of the study.^[1]

Like an ethnography, a diary study, too, is carried out over a significantly longer duration of time. It can help determine user needs, goals, personas, and behaviors. In particular, it allows researchers to identify how users carry out and complete certain tasks.^[2] It is most useful at the beginning of the UX design process.

After the logging period, researchers can go through the entries and conduct follow-up interviews. This can fill in any gaps in the diary entries and clarify unclear parts.