F2008-02-007
The Y Law - A Fundamental Guide to Design MMIs
The paper aims to present a new characterization of the human behavior, applied here to general customers. This law has been discovered when studying in depth the user-in-the-loop actions when trying to disconnect the Cruise Control function in emergency (At that date the author was in charge of a Transverse Team on simplifying the use of complex functions within Renault). The definition is the following : "Under a stressed situation or when the user refuses to allocate important resources from its brain (because he cannot or because he refuses to do it), this person will memorize the existence of a choice rather the elements of this choice. Any added help or explanation is superfluous and cannot become acquired." The name "Y" comes from an analogy with the neurons architecture in the brain. The law tells us that the preferred mode of operation of the human beings is to settle one neuron to memorize that there is a choice rather than to allocate two neurons to save the conditions of the choice. This law is very important when designing secure systems, fast reaction anticipations, and alarm notifications. The paper describes the conflict between the speedy cerebellum which is optimized to act on a reflex mode, compare to the cognitive brain which operates on a reflexive mode. Designing an MMI system according to this law brings simplicity for the user, which means pleasure and security in the usage. Illustrations are given as well elements for discussion (pros and cons). In particular, it is stressed how wrong modern multimedia embedded systems (car controls, GPS/Phone/Music) are designed. New MMI architectures are recommended as a conclusion and their impact on the organization is underlined.
Poster presentation: Man-Machine-Interaction