Oral stage, the first step of his theory, sees infants become attached to an object that provides oral fulfillment. Freud believed that infants develop maternal relationships because mothers feed them and satisfy their hunger. However, animal studies have provided evidence that feeding does not necessarily explain the attachment. In fact, experiments have found that infant rhesus monkeys raised in an isolated environment preferred the contact with a comfortable cloth-covered surrogate mother, even while feeding from the nourishing wire surrogate mother, demonstrating that the basis for attachment relationships does not reside solely in feeding. These experiments also found that the ones raised by simulated mothers were scared when placed alone in foreign situations (Harlow & Zimmermann, 1958).
Another expert, Erik Erikson, proposed an eight-stage psychosocial development process. In his theory, each stage involves a task that must be completed if infants are to successfully move to the next stage. The initial stage of "Trust versus mistrust" in psychosocial development arises in the first year of life. During this stage infants need to develop a sense of trust in themselves and in the world around them. The infant depends on the parents, with an emphasis on the mother, for nourishment. Their relative interpretation of world and society stems from the parent-child interaction. If the parents expose the child to consistency, and steady affection, the child's perception will be that of trust. However, if parents fail to provide a safe environment that meets the needs of the child, it will lead to mistrust. A development of mistrust could precede feelings of blocking, skepticism, extraction, and an overall lack of confidence (Davis et al., 2013). It was Erikson's belief that these patterns formed during early development heavily influence a person's interactions for the remainder of their life.