Joseph Campos: UC Berkeley Department of Psychology

There is a fascinating paradox about fear of heights in humans and some animal species. Such fear has enormous biological adaptive value, represents a true life-span emotional reaction, and constitutes one of the strongest and most reliably-elicited fears in the human. As such, one would expect fear of heights to be innate, or under strong maturational control. Indeed, until recently, it was so considered. However, there is now no doubt that fear of heights develops as the result of experience, more specifically experiences linked to the onset of self-produced locomotion. It is not a maturational or innate event.

What creates fear of heights and how does locomotor experience play a role in its ontogeny? We can rule out three likely candidates as playing a causal role. Depth perception is well established before such fear develops; falling experiences are relatively rare; and maternal emotional signaling has little if any impact at the age of onset of locomotion. What, then, may be the process(es) by which such biologically-adaptive wariness comes about?

In this talk, evidence is presented for the role of a discrepancy between sensory systems in the ontogeny of these fears. The discrepancy we propose to be playing a causal role is related to the discrepancy that in adults makes heights “dizzying.” More specifically, one experiences height vertigo when information reaches the brain that the head and body is moving (even minutely so), but visual information discrepantly fails to confirm such self-movement. It turns out that infants have good vestibular and kinesthetic information about self-movement from early in life, but lack responsiveness to flow in the visual periphery until after the acquisition of locomotor experience. So, only after “visual proprioception” becomes functional is the infant capable of experiencing the discrepancy that produces height vertigo.

The talk will:

(a) Visually illustrate what visual proprioception is (it is not a phenomenon well-known to behavioral scientists),

(b) Provide evidence for the role of locomotor experience on visual proprioception, and

(c) Present results of two studies showing correlations between responsiveness to optic flow and the probability of showing wariness of heights in infants at two different ages.
http://www.bec.ucla.edu/papers/Campos_24.4.06.doc