Such a reaction may include varying degrees of non-perception, mis-perception, non-recognition, non-understanding, or non-acceptance of certain realities in order to cope with otherwise unacceptable intra-psychic conflicts, feelings or memories. People also unconsciously resort to denial as a reaction to threats that they feel unable to cope with; such denial in turn detracts from and inhibits their potential ability to resolve problems realistically. Another aspect of non-acceptance of reality is the failure to comprehend the consequences of an event that has not only never been experienced personally, but is unimaginable because of its extraordinary magnitude.
Modern examples are the threats of nuclear, chemical and biological warfare. The difficulty of facing the massive and unprecedented nature of these threats may be so great that many people simply choose to ignore their existence, or meet the threat with the notion of 'it can't happen to us'.