Egocentrism is another Piagetian theory and is often shown in the pre-operational stage, according to Piaget the child will find it difficult to see the world from another person's perspective and understand that not everyone sees the world in the same way (Piaget, 1995). Egocentrism can have a strong influence on moral development; for example, if the child is unable to see from another person's point of view, he or she is unlikely to be empathetic (Boom, 2011). According to Gibbs (2003), egocentrism begins to decrease as working memory strengthens and the child begins to experience social perspective-taking experiences, although a person will never fully emerge from it. The principle of false belief is the understanding that depending on the information a different person has, they may not be able to find an answer, for example if the rock is painted to look like an orange, another person would not be able to tell that an orange is not orange without touching it (Flavell, Miller & Miller, 1993). To be able to understand the false belief principle, a child would not be able to be very self-centered or would not be able to understand that the person would not know that the orange is a rock without touching it. Theory of mind develops over a period of three to four years, it is measured by approaching the child with some ideas and asking them