In any case, aggression and violence in children may well be innate. They typically are aggressive towards their carer or towards other children, or throw tantrums in public, all ways of testing the carer's boundaries and through which they learn to contain their aggression. The explicit demonstration of violence and aggression by a filmed adult seems under these circumstances bound to lead to aggressive behaviour on the part of the child, the experimenters thereby succeeding in confirming their original hypothesis. In fact, the children who had not seen the film also knocked the doll around. Another criticism is that the laboratory environment is not real life.
People behave differently in a laboratory environment.
Some studies appear to have shown that the kind of behaviour imitated in the laboratory is in fact subject to controls outside the laboratory. One of the reasons that field studies generally show less effect than laboratory studies is almost certainly that the normal constraints and controls as to what is acceptable behaviour are suspended in the artificial laboratory environment. Another is the relative absence of experimenter demand. In Bandura's experiment the sample sizes have been matched, as have the methods of selection of the experimental group and the control group. In effect, it becomes impossible to draw any firm conclusions because we don't know how representative they were.