In Bandura, Ross and Ross's (1961) study on the transmission of aggression, how did the researchers control for the potential confounding variable of individual differences in the children's baseline aggression levels?
They used a repeated measures design where every child was exposed to both the aggressive and non-aggressive models, separated by a one-week delay to allow aggression to return to baseline.
They matched the children in triplets based on ratings of pre-existing aggression by a teacher and an experimenter, then randomly allocated one child from each triplet to each condition.
They recruited a very large sample of 720720720 children to ensure that individual differences in baseline aggression would naturally balance out across groups via simple random allocation.
They pre-screened the children using parental self-report questionnaires and excluded any children who scored exceptionally high or low in baseline aggression.
