What can be the outcome of short social isolation in children?

In Psychology, we've been learning about the case study on Genie (the child who had complete social isolation until she was 13, and was unable to walk or talk when she was found). In one of the doentaries, one of the psychiatrists interviewed said that when young children (I'm guessing from ages 2-6?) are forced into social isolation for even an hour, the effects on their development can be devastating. I was just wondering if this was correct, and if so, what kind of effects would this have?