image as a face, there is activity in the temporal lobe, specifically in the face-selective region. An additional example is the "My Wife and My Mother-in-Law" illusion drawing. The image is famous for being reversible. "The viewer may either observe a young girl with her head turned to the right or an old woman with a large nose and protruding chin, depending on one's perspective." Development Figure–ground perception precedes all other visual perceptual skills and is one of the first to develop in a young baby. The development of perceptual organization develops as early as infancy in human beings. In regards to nature versus nurture, concepts such as "lightness" and "proximity" may develop as early as birth, but recognizing "form similarity" may not be functional until activated by particular experiences. Three- to four-month olds respond to differences in lightness rather than differences in form similarity. It is suggested that scaffolding (the development of new skills over time based on the building of other skills) is responsible for the development of perceptual organization. Environment plays a major role in the development of figure-ground perception. The development of figure–ground perception begins the day the baby can focus on an object. The faces of caregivers, parents, and familiar objects are the first to be focused on and understood. As babies develop, they learn to distinguish the objects they desire from their surroundings. Sitting up, crawling, and walking present ample opportunity to develop the skill during development. Between the ages of 2–4 the skill can be further cultivated by teaching the child to group or sort items. Perceptual process The perceptual decision in which the brain decides which item is the figure and which are part of the ground in a visual scene can be based on many cues, all of which are of a probabilistic nature. For instance, size assists in distinguishing between the figure and the ground, as smaller regions are often (but not always) figures. Object shape can assist in distinguishing figure from ground because figures tend to be convex. Movement also helps; the figure may be moving against a static environment. Color is also a cue because the background tends to continue as one color behind potentially multiple foreground figures, whose colors may vary. Edge assignment also helps; if the edge belongs to the figure, it defines the shape while the background exists behind the shape. However, it is sometimes