Traditionally, acrophobia has been attributed, like other phobias, to
conditioning or a
traumatic experience. Recent studies have cast doubt on this explanation. Individuals with acrophobia are found to be lacking in traumatic experiences. Nevertheless, this may be due to the failure to recall the experiences, as memory fades as time passes. To address the problems of self report and memory, a large cohort study with 1000 participants was conducted from birth; the results showed that participants with less fear of heights had more injuries because of falling. More studies have suggested a possible explanation for acrophobia is that it emerges through accumulation of non-traumatic experiences of falling that are not memorable but can influence behaviours in the future. Also, fear of heights may be acquired when infants learn to crawl. If they fell, they would learn the concepts about surfaces, posture, balance, and movement. Experiencing these cognitive factors while associating them with the idea of falling may be enough to cause the same fear that would be expected after a traumatic fall. A fear of falling, along with a
fear of loud noises, is one of the most commonly suggested inborn or "non-associative" fears. The newer non-association theory is that a fear of heights is an evolved adaptation to a world where falls posed a significant danger. If this fear is inherited, it is possible that people can get rid of it by frequent exposure of heights in
habituation. In other words, acrophobia could be associated with a lack of exposure to heights in early life. The degree of fear varies, and the term
phobia is reserved for those at the extreme end of the spectrum. Researchers have argued that a fear of heights is an instinct found in many mammals, including domestic animals and humans. Experiments using
visual cliffs have shown human
infants and
toddlers, as well as other animals of various ages, to be reluctant in venturing onto a glass floor with a view of a few meters of apparent fall-space below it. Although human infants initially experienced fear when crawling on the visual cliff, most of them overcame the fear through practice, exposure and mastery and retained a level of healthy cautiousness. While an innate cautiousness around heights is helpful for survival, extreme fear can interfere with the activities of everyday life, such as standing on a ladder or chair, or even walking up a flight of
stairs. It is uncertain if acrophobia is related to the failure to reach a certain developmental stage. Besides associative accounts, a
diathetic-stress model is also very appealing for considering both vicarious learning and hereditary factors such as personality traits (i.e., neuroticism). Another possible contributing factor is a dysfunction in maintaining balance. In this case, the anxiety is both well-founded and secondary. The human balance system integrates
proprioceptive,
vestibular and nearby visual cues to reckon position and motion. As height increases, visual cues recede and balance becomes poorer in people without acrophobia. However, most people respond to such a situation by shifting to more reliance on the proprioceptive and vestibular branches of the equilibrium system. Some people are more dependent on visual signals than others. People who rely more on visual cues to control body movements are less physically stable. Recent studies found that participants experienced increased anxiety not only when the height increased, but also when they were required to move sideways at a fixed height. A recombinant model of the development of acrophobia is very possible, in which learning factors, cognitive factors (e.g. interpretations), perceptual factors (e.g. visual dependence), and biological factors (e.g.
heredity) interact to provoke fear or habituation. == Assessment ==