A flashbulb memory is a vivid, long-lasting memory about a surprising or shocking event that has happened in the past. The term "flashbulb memory" suggests the surprise, indiscriminate illumination, detail, and brevity of a photograph; however, flashbulb memories are only somewhat indiscriminate and are far from complete. Evidence has shown that although people are highly confident in their memories, the details of the memories can be forgotten. Flashbulb memories are one type of autobiographical memory. Some researchers believe that there is reason to distinguish flashbulb memories from other types of autobiographical memory because they rely on elements of personal importance, consequence, emotion, and surprise. Others believe that ordinary memories can also be accurate and long-lasting if they are highly distinctive, personally significant, or repeatedly rehearsed. Flashbulb memories have six characteristic features: place, ongoing activity, informant, own affect, other affect, and aftermath. Arguably, the principal determinants of a flashbulb memory are a high level of surprise, a high level of consequentiality, and perhaps emotional arousal. Historical overview The term flashbulb memory was coined by Brown and Kulik in 1977. They formed the special-mechanism hypothesis, which argues for the existence of a special biological memory mechanism that, when triggered by an event exceeding critical levels of surprise and consequentiality, creates a permanent record of the details and circumstances surrounding the experience. Brown and Kulik believed that although flashbulb memories are permanent, they are not always accessible from long term memory. The hypothesis of a special flashbulb-memory mechanism holds that flashbulb memories have special characteristics that are different from those produced by "ordinary" memory mechanisms. The representations created by the special mechanism are detailed, accurate, vivid, and resistant to forgetting. Most of these initial properties of flashbulb memory have been debated since Brown and Kulik first coined the term. Ultimately over the years, four models of flashbulb memories have emerged to explain the phenomenon: the photographic model, the comprehensive model, the emotional-integrative model, and importance-driven model; additional studies have been conducted to test the validity of these models. Positive vs. negative It is possible for both positive and negative events to produce flashbulb memories. When the event is viewed as a positive event, individuals show higher rates of reliving and sensory imagery, also showed having more live-qualities associated with the event. Individuals view these positive events as central to their identities and life stories, resulting in more rehearsal of the event, encoding the