The Organization of Wariness of Heights in Experienced Crawlers

Most infants with more than 6 weeks of crawling experience completely avoid the deep side of a visual cliff (Campos et al., 1992; Gibson & Walk, 1960). However, some experienced crawlers do move onto the transparent surface suspended several feet above the ground. An important question is whether these non-avoiders lack wariness of heights or whether they have a qualitatively different way of showing their wariness than do avoiders of the deep side. The current study addressed this question by measuring heart rate (HR) acceleration upon being lowered on the deep and shallow sides of the visual cliff, latency to crawl toward the mother, and tactile exploration of the cliff surface. Non-avoiders and avoiders had indistinguishable patterns of HR acceleration, showing greater HR acceleration when lowered onto the deep than when lowered onto the shallow side of the cliff. Non-avoiders also showed more tactile exploration and longer latencies than did a comparable group of infants tested on the shallow side. This study illustrates how the same emotion, wariness of heights, can be shown by qualitatively different behaviors, all serving the same function of protecting the individual from falling over a drop-off.