Depth Perception, Locomotion and Social Referencing:
For decades, researchers have been fascinated with the way infants reach their milestones and acquire their capacity to see, manipulate objects, crawl and develop language. Although the infants' development can be observed in their naturalistic environment, it is difficult to study their growth from a scientific perspective. The apparatus of the visual cliff that was initially created to assess young children's ability to perceive depth has enabled scientists to create a quasi-naturalistic setting and obtain quantifiable data. This paper offers a comprehensive look at the role of the visual cliff in the study of child development. First, the study of depth perception will be explored briefly to illustrate the underlying reason for the invention of the visual cliff. Second, the visual cliff and the original experiments will be presented. Finally, the variations of the visual cliff by researchers to study other areas of child development, which are linked to depth perception, will also be analyzed. Depth perception of young children/infants: Binocular perception and stereopsis Depth perception depends on two components, binocular perception and stereopsis. Binocular perception occurs when both eyes are able to work together and focus on one visual object at the same time. Because of the distance between the two eyes, the two retinas are stimulated differently, thus enabling one to assess how far one is from the object. Stereopsis involves the combination of two separate images from the eyes into one integrated image in the brain. The process of depth perception enables one to see three-dimensional images even when the retinas registers two-dimensional pictures. The transformation from two-dimensional to three-dimensional images occurs in the brain that has learned to manipulate visual images by comparing sizes, orientations, object overlaps and shadows (Berk, 1997; Siegler, 1998, p. 121). Before the age of four months, infants do not have binocular depth perception. The images transmitted from their eyes reach the same cells in the visual cortex. However, once they are four months old, infants typically develop depth perception when the neural pathways from the eye to the brain are separated. While visual images from the left eye reach some cells in the brain, the images from the right eye arrive at other cells. The differences in the input transmitted from the two eyes enable the brain to produce depth perception (Siegler, 1998, p. 121). Because of the consistent occurrence of stereopsis at around four months of age, its development was initially attributed simply to the process of maturation. However, scientists who assessed this theory by using drugs to prevent the segregation of pathways at the usual time of the development of stereopsis found that depth perception was undermined. Essentially, maturation in itself does not produce depth perception. Rather, the maturation process combined with experiences in the environment enable infants to develop their capacity for depth perception (Siegler, 1998, p. 121). The latter theory was further confirmed by studies on cross-eyed children and adults who required surgery to correct their condition. Although both the children and adults developed binocular vision after the surgery, they did not necessarily possess binocular depth perception. Banks, Aslin and Letson (1975) found that the subjects who had surgery before the age of three possessed normal binocular depth perception. Apparently, there was a small window period between the age of four months and three years for normal binocular depth perception to develop. After the age of three, the development of depth perception was undermined (in Siegler, 1998, p. 121). The first experiments of the "visual cliff"
One of the earliest experiments to determine how infants acquire depth perception involves the use of an apparatus called the "visual cliff" that was...
Please join StudyMode to read the full document