Head and shoulders, knees and toes: which parts of the body are necessary to be seen?

Children aged 2 and 3 years were tested for a previously neglected form of knowledge about visual perception; namely, whether an observer can see a figure that is partially occluded. The results indicate that for children of this age the visibility of a figure's face is crucial for judging visibility, whereas the visibility of the legs is not. This phenomenon is limited to human-like figures. Results are explained in terms of engagement, a precursor to a mature understanding of attention.