has not yet been determined; however, there have been some speculations that it supports children's fledgling social skills. Toys and props In a study by Welsch, children provided with props showed sophisticated levels of play. In pretend play, any object in the child's surroundings can be used as a prop. Substitution Any object can be integrated into pretend play as a representation of another object. This kind of representation is referred to as substitution. The ability to substitute one object for another emerges when a child is about 2 years old. In early instances of substitution, children are only capable of substituting objects that either have a similar structure or a similar function. For example, a child can pretend that a pen is a toothbrush, or that a television remote is a telephone. A pen has roughly the same shape as a toothbrush, while the remote has buttons that function similarly to a telephone. Around the age of 3, the child begins to master substitution and no longer needs physical or functional similarity between the actual object and the substitute. The child also becomes capable of substitution without the use of a concrete object, thus depending solely on imagination (e.g. putting their palm to their ear and having a conversation, indicating a phone call). The ability to hold more than one substitution at a time also increases, meaning that the child can pretend to be on the phone, walking a dog, and sipping juice all at once. There are two types of substitutions. Symbolic substitution is when one object is used to represent another, such as when a coach uses sticks to represent players in a game plan. Hypothetical substitution is when one object is used "as-if" it actually is another object, such as the previous example of imagining that a pen functions as a toothbrush. Doll play Pretense with dolls begins when a child extends pretend self actions to a doll. A child might start by pretending to feed themselves, then reach out and pretend to be feeding a doll. This is further developed when a child begins giving the doll an active role rather than a passive one. For example, the doll doesn't just eat when fed by the child, instead, the child pretends that the doll reaches for the spoon and feeds itself. After the doll is given an active role, the child begins to bestow upon