In prehistoric times when language was less developed, humans could already form associations between good or bad experiences and the situations in which they took place. This form of emotional learning does not require conscious thought. Certain stimuli become significant as either safe or threatening.
Prehistoric man would have experienced a situation as dangerous because he felt anxious in that place where something bad had previously occurred. So internal sensations were the basis for knowing a fight or flight response was necessary. These reactions happened naturally and ensured the survival of the species. Those fear responses were valuable because they were triggered by environmental stimuli associated with dangerous situations. The spread to similar stimuli is called stimulus generalisation.
Since that time, the human brain has developed language, rational thought and the power to imagine potentially real events or creations. These abilities are the basis for the whole of civilization's scientific discoveries and creative expressions. However, the need to trigger an escape mechanism rapidly, a fight or flight reaction with its accompanying extreme physiology, placed a survival value on having a shorter pathway in the brain to the centres responsible for response to danger than to rational thought. This is the reason, why still today, people experience panic before they realise that the situation they are in is a safe one. It is as if it is better to escape and be safe than to be right.
Another complication is that the brain does not distinguish between an imaginary situation or event and a real one. After all, the mental image of a threat, might be a response to a stimulus that has at one time been associated with danger. So, the disadvantages of our highly evolved brain are that we respond to danger before we have made a judgement of whether there is danger present and also that we switch into threat response mode as a response to thoughts and images rather than to stimuli in the environment.
People vary in their readiness to access a fight, flight or defensive mode as a result of past experience. Someone who has experienced ongoing threat over a period of time, perhaps as a child is likely to expect danger everywhere, however safe their actual situation. A person who has been through a life-threatening event may react as if threatened in that way when any similar stimuli occur, even if the situation is safe. This is common in post-traumatic stress disorder. For some people, the likelihood of accessing a state of fearfulness, panic or escape mode, is influenced by traumatic experiences, however long ago they occurred.
