The Oral Sensory Stage takes place during infancy, which is birth through 18 months. During this time babies explore the world around them by putting everything in their mouth. During this time they are developing their sense of trust vs. mistrust. If the baby experiences positive love and care during this time (especially from the mother), they will learn to trust that life is basically ok and that they will be cared for. If they fail to have their needs met during this time, they may end up with feelings of worthlessness and a sense of mistrust towards others.
The oral-sensory stage is the infant's first stage of life, when they are responding by instinct to the world around them. This is the stage when children are learning to trust, relying on others for their food and comfort. This is also the stage highlighted by a mother's nurturing and cuddling. The oral aspect of the stage refers concretely to the breast-feeding of the young infant, which is their first interaction with the world around them and with other people. Children will continue to orally experience the world around them for some time as they grow - which is why toddlers put so many items in their mouth! The sensory part of the stage's name refers to their sight, hearing, taste and touch, the other elements of their experience with the world at this young age. There is no cognitive reasoning - it is all about senses and stimuli.
The first stage Trust vs. Mistrust applies to infants from birth to 12 months. In this stage, the newborn must develop trust so it can see the world as a safe place. The infant must obtain physical comfort and no fear of the future. The child obtains this belief through the comfort and care it receives by his parents. If the child is not held enough, fed enough, cleaned enough etc. then the kid will develop mistrust and see the world as an unsafe environment. It is however important to remember that a child can develop mistrust as they grow older.