 Daydreaming is a short-term detachment from one's immediate surroundings, during which a person's contact with reality is blurred and partially substituted by a visionary fantasy, especially one of happy, pleasant thoughts, hopes or ambitions, imagined as coming to pass, and experienced while awake. There are many types of daydreams, and there is no consistent definition amongst psychologists, however the characteristic that is common to all forms of daydreaming meets the criteria for mild dissociation. Negative aspects of daydreaming were stressed after human work became dictated by the motion of the tool. As craft production was largely replaced by assembly line that did not allow for any creativity, no place was left for positive aspects of daydreaming. It not only became associated with laziness, but also with danger. For example, in the late 19th century, Tony Nelson argued that some daydreams with grandiose fantasies are self-gradifying attempts at wish fulfillment. Still in the 1950s, some educational psychologists warn parents not to let their children daydream, or fear that the children may be sucked into neurosis and even psychosis.