A phenomenon of memory in which information that is analyzed deeply is better recalled than information that is analyzed superficially.1

Thinking hard about information improves the likelihood that the information will be recalled at a later time. For example, consider two tasks that involve interacting with and recalling the same information. In the first task, a group of people is asked to locate a keyword in a list and circle it. In the second task, another group of people is asked to locate a keyword in a list, circle it, and then define it. After a brief time, both groups are asked to recall the keywords from the tasks. The group that performed the second task will have better recall of the keywords because they had to analyze the keywords at a deeper level than the group in the first task; they had to think harder about the information.2

This phenomenon of memory results from the two ways in which information is processed, known as maintenance rehearsal and elaborative rehearsal. Maintenance rehearsal simply repeats the same kind of analysis that has already been carried out. For example, people often use maintenance rehearsal when they repeat a phone number back to themselves to help them remember; no additional analysis is performed on the phone number. Elaborative rehearsal involves a deeper, more meaningful analysis of the information. For example, people engage in elaborative rehearsal when they read a text passage and then have to answer questions about the meaning of the passage; additional analysis as to word and sentence meaning require additional thought. Generally, elaborative rehearsal results in recall performance that is two to three times better than maintenance rehearsal.3

The key determining factors as to how deeply information is processed are the distinctiveness of the information, the relevance of the information, and the degree to which the information is elaborated. Distinctiveness refers to the uniqueness of the information relative to surrounding information and previous experience. Relevance refers to the degree to which the information is perceived to be important. The degree of elaboration refers to how much thought is required to interpret and understand the information. Generally, deep processing of information that involves these factors will result in the best possible recall and retention of information.4

Consider depth of processing in design contexts where recall and retention of information is important. Use unique presentation and interesting activities to engage people to deeply process information. Use case studies, examples, and other devices to make information relevant to an audience. Note that deep processing requires more concentration and effort than mere exposure (e.g., classroom lecture), and therefore frequent periods of rest should be incorporated into the presentation and tasks.