or communities followed. Jenkinson's approach was to describe an imaginal character in their real interface, behavior and attitudes with the brand, and the idea was initially realized with Michael Jacobs in a series of studies. In 1997 the Ogilvy global knowledge management system, Truffles, described the concept as follows: "Each strong brand has a tribe of people who share affinity with the brand’s values. This universe typically divides into a number of different communities within which there are the same or very similar buying behaviours, and whose personality and characteristics towards the brand (product or service) can be understood in terms of common values, attitudes and assumptions. CustomerPrints are descriptions that capture the living essence of these distinct groups of customers." Benefits According to Pruitt and Adlin, the use of personas offers several benefits in product development. Personas are said to be cognitively compelling because they put a personal human face on otherwise abstract data about customers. By thinking about the needs of a fictional persona, designers may be better able to infer what a real person might need. Such inference may assist with brainstorming, use case specification, and features definition. Pruitt and Adlin argue that personas are easy to communicate to engineering teams and thus allow engineers, developers, and others to absorb customer data in a palatable format. They present several examples of personas used for purposes of communication in various development projects. Personas also help prevent some common design pitfalls which may otherwise be easy to fall into. The first is designing for what Cooper calls "The Elastic User", by which he means that while making product decisions different stakeholders may define the 'user' according to their convenience. Defining personas helps the team have a shared understanding of the real users in terms of their goals, capabilities, and contexts. Personas also help prevent "self-referential design" when the designer or developer may unconsciously project their own mental models on the product design which may be very different from that of the target user population. Personas also provide a reality check by helping designers keep the focus of the design on cases that are most likely to be encountered for the target users and not on edge cases which usually will not happen for the target population. According to Cooper, edge cases which should naturally be handled properly should not become the design focus. The persona benefits are summarized as