It is often assumed that recall decline follows a curve similar to those in the following figures. These figures illustrate the recall rate for people exposed to an advertising message at the rate of one time per week for a period of three weeks.

Figure 1 - Recall with Good Retention

The figure above was created using the Audience Analysis System , and shows the rate of recall over time where this rate declines relatively slowly. The figure below shows the rate of recall over time where this rate declines more rapidly.

Figure 2 - Recall with Poor Retention

For purposes of advertising campaign optimization, the rate of recall decline can often be estimated by those who are familiar with the performance of the advertised product in the marketplace.

For television promotional campaigns, these rates, for some selected conditions, have been computed. See A Network Television Viewing Choice Model for Optimizing Program Promotion Scheduling.

Using the Audience Analysis System , advertising and promotional campaigns can be optimized based on either learning/recall or reach .