Dr. Levy reports his experiments in the use of play technic with children having younger siblings. The ten children studied had been referred for serious deviations in behaviour. The situations in the play were arranged to encourage the expression of sibling rivalry by the use of dolls representing those involved in the situation—namely, the mother, the baby and older child. Through playing a game of nursing of the baby by the mother, the child being examined identifies himself with the older doll and the expression of his hostility comes to light frequently in violent or destructive manifestations against the baby or the mother.

Dr. Levy quotes statistics to shew the frequency of sibling rivalry in normal groups, but concludes that in larger families there is a diminished percentage of rivalry frequency. Five cases are cited in which the play technic exerted favourable influence in the adjustment of the child's problems through offering opportunity to release the repressed hatred.