The study, published in the September issue of Family Psychology, detailed several aspects of how preferential treatment involving parental control (being less strict or punitive with one child than with another) and affection (showing more interest or enjoyment in one child) may affect siblings.
Researchers, in general, found that when siblings perceive that such treatment of one of them is fair, each child is less prone to problems such as depression and anxiety and more likely to have higher self-worth. However, they noted, "enhanced socio-emotional well-being is not ensured by the perception that parental preferential treatment is fair."
"A lesson to be learned is that parents should seriously consider how children view the legitimacy of preferential treatment," said investigator Laurie Kramer, a professor in the department of human and community development at the University of Illinois at Urbana-Champaign. "Not only can parents simply believe their parenting behavior is warranted or fair, they need to make their reasoning clear to their children."
Researchers interviewed 135 children, about 12 years old, and their older siblings, about 15 years old, who were told there were no wrong or right answers to any of their responses. The children rated the degree to which their mothers and fathers treated them and their siblings preferentially or equally in terms of parental control and affection. They next rated whether they felt that each instance of preferential treatment was fair or unfair.
The children also completed a standard self-worth questionnaire, and mothers responded to a 118-item child-behavior checklist about each of their participating children.
The mothers' responses allowed researchers to measure depression, social withdrawal and somatic complaining, all internalizing behaviors, as well as the externalizing behaviors of aggressiveness, delinquency and hyperactivity of the children.
Children agreed that younger siblings are more likely to get preferred maternal affection and preferred maternal and paternal control. In 78 percent of the cases of preferential treatment, the children said it was fair. Children did not simply consider parental behaviors in their favor as fair and those favoring their sibling as unfair.
"The key idea is that -- contrary to the common assumption that children and adolescents suffer when they receive poorer treatment from a parent than a sibling and thrive when they receive preferred treatment -- what's really important is whether children believe the parental treatment is fair or not," Kramer said. "Children receiving better treatment than a sibling may have difficulties if they don't believe they are entitled to it."
The study helps provide a broader picture to the issue of unequal parental treatment. In 1997, Kramer and then Illinois doctoral student Amanda Kowal looked at differential treatment of siblings, considering such issues as parental strictness, punishment and blame, along with the quality of relationships. In the journal Child Development, they reported that when older children understood why differential treatment was occurring they perceived it as fair and had warmer and closer relationships with younger siblings.
"The major difference is that the earlier paper focused on the effects of the fairness of differential treatment on the quality of the sibling relationship, whereas this one has the personal well-being of individual siblings as the outcome," Kramer said. "The current paper also focuses on preferred treatment rather than differential treatment -- a subtle difference. The story line is similar; perceptions of fairness matter."
In addition to Kramer, authors of the new paper were Kowal, now a professor at the University of Missouri at Columbia; Jennifer L. Krull, also of Missouri; and former Illinois professor Nicki Crick of the University of Minnesota. The U.S. Department of Agriculture and the Fahs-Beck Fund for Research and Experimentation funded the study.
Journal of Family Psychology