The photographic model Brown and Kulik proposed the term flashbulb memory, along with the first model of the process involved in developing what they called flashbulb accounts. The photographic model proposes that in order for a flashbulb account to occur in the presence of a stimulus event, there must be, a high level of surprise, consequentiality, and emotional arousal. Specifically, at the time in which an individual first hears of an event, the degree of unexpectedness and surprise is the first step in the registration of the event. The next step involved in registration of flashbulb accounts is the degree of consequentiality, which in turn, triggers a certain level of emotional arousal. Brown and Kulik described consequentiality as the things one would imagine may have gone differently if the event hadn't occurred, or what consequences the event had on an individual's life. Further, Brown and Kulik believed that high levels of these variables would also result in frequent rehearsal, being either covert ("always on the mind") or overt (ex. talked about in conversations with others). Rehearsal, which acts as a mediating process in the development of a flashbulb account, creates stronger associations and more elaborate accounts. Therefore, the flashbulb memory becomes more accessible and vividly remembered for a long period of time. Comprehensive model Some researchers recognized that previous studies of flashbulb memories are limited by the reliance on small sample groups of few nationalities, thus limiting the comparison of memory consistency across different variables. The comprehensive model was born out of similar experimentation as Brown and Kulik's, but with a larger participant sample. One major difference between the two models is that the Photographic Model follows more of a step-by-step process in the development of flashbulb accounts, whereas the Comprehensive Model demonstrates an interconnected relationship between the variables. Specifically, knowledge and interest in the event affects the level of personal importance for the individual, which also affects the individual's level of emotional arousal (affect). Furthermore, knowledge and interest pertaining to the event, as well as the level of importance, contribute to the frequency of rehearsal. Therefore, high levels of knowledge and interest contribute to high levels of personal importance and affect, as well as high frequency of rehearsal. Finally, affect and rehearsal play major roles in creating associations, thus enabling the individual to remember vivid attributes of the event, such as the people, place, and description of the situation.