the retrieval of emotional scenes presented in the laboratory and flashbulb memories suggests that even though different mechanisms may be involved in flashbulb memories, these mechanisms are not unique to the surprising and consequential nature of the initiating events. Evidence indicates the importance of the amygdala in the retrieval of 9/11 events, but only among individuals who personally experienced these events. The amygdala's influence on episodic memory is explicitly tied to physiological arousal. Although simply hearing about shocking public events may result in arousal, the strength of this response likely varies depending on the individual's personal experience with the events. Critique of research Flashbulb memory research tends to focus on public events that have a negative valence. There is a shortage on studies regarding personal events such as accidents or trauma. This is due to the nature of the variables needed for flashbulb memory research: the experience of a surprising event is hard to manipulate. Also, it is very hard to conduct experiments on flashbulb memories due to lack of control over the events. In an empirical study, it is very difficult to control the rehearsal amount. Some researchers also argue that the effect of rehearsal factors on individual memory is different with respect to the availability of the mass media across different societies. See also Memory and trauma Yerkes–Dodson law Now Print! References Memory