With respect to frequency objectives, the planner must determine the optimal level of frequency in order to achieve the desired communications objective. Media planners often work with rules of thumb for setting frequency objectives that are based on an extensive body of evidence drawn from research findings. For example, empirical evidence suggests that the average consumer needs to be exposed to a message at least three times before they become aware of the brand information. This is sometimes known as the "3+ Rule". To this basic benchmark of three exposures, media planners recognise that to achieve higher-level communication goals, such as persuasion and lead generation, higher levels of frequency are required. To achieve simple brand awareness, three exposures may be sufficient, but for consumers to act on that awareness, higher levels of exposure may be required. Some theorists have developed sophisticated decision models to assist with planning optimal frequency levels.