spring forward upon its surface. Based on the results of the animals tested, the danger and fear of falling is instilled in animals at a very young age. Factors that influence the fear of falling Postural control The postural control system has two functions: to ensure that balance is maintained by bracing the body against gravity, and to fix the orientation and position of the features that serve as a frame of reference for perception and action with respect to the external world. Postural control relies on multisensory processing and motor responses that seem to be automatic and occur without awareness. Studies have shown that people afraid of heights or falling have poor postural control, especially in the absence of strong visual cues. These individuals rely heavily on vision to regulate their posture and balance. When faced with high or unstable ground, the vestibular system in these individuals senses the instability and attempts to correct it by increasing postural sway to reactivate visual balance feedback (postural sway refers to the phenomenon of constant displacement and correction of the position of the center of gravity within the base of support). This often fails, however, resulting in a feeling of increased instability and anxiety, which is often interpreted as fear. Height vertigo Closely related to postural control is the sensation of vertigo: a warning signal created by a loss of postural control when the distance between the observer and visible stationary objects becomes too large, and caused by a dysfunction of the vestibular system in the inner ear. In short, it is the feeling of motion when one is actually stationary. Symptoms of vertigo include dizziness, nausea, vomiting, shortness of breath, and the inability to walk or stand. Some individuals are more reliant on visual cues to control posture than others. Vestibular sensations can arise when unsound information is detected along the sensory channels (this happens even to those with normal vestibular function), and feelings of vertigo can result in people with postural control issues. Space and motion discomfort Studies have shown that people with acrophobia and/or an extreme fear of falling have higher scores of SMD, or space and motion discomfort. These are physical symptoms elicited by visual or kinesthetic information that is inadequate for normal spatial orientation. Space and motion discomfort arises when conflicting information is detected among visual, kinesthetic, and vestibular sensory channels. Evidence has supported the claim that