There are many problems with assaying gender differences found in the research into this topic. Most apparent is that it is heavily reliant on self-reporting of events. Inaccuracy of findings could result from bias questions or misremembering on the part of the participants. There is no way to completely verify the accuracy of accounts given by the subjects in a study. Additionally there are many indications that eye-witness memory can often be fallible. Emotion does not seem to improve memory performance in a situation that involves weapons. One study found that eyewitnesses remembered details about perpetrators less clearly when a weapon was involved in the event (Pickel, 2009). Accuracy in these situations is compromised by a phenomenon known as the weapon focus effect. Further complicating matters is the time frame in which people are surveyed in relation to the event. Many studies fall victim to surveying people well after the events have transpired. Thus, there is a validity issue with much of the research into flashbulb memory in general, as well as any apparent gender differences found therein.