Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Frank J. Floyd, Ph.D. - Chair


This study examined mechanisms by which sibling relationships may buffer the harmful effects of negative peer experiences on the psychological adjustment of children with mental retardation (MR) or learning disabilities (LD). The study broadened existing findings with typically developing children and examined the effects of sibling social competency training on peer experiences and the impact of sibling relationship qualities, including warmth and positivity, supportiveness, conflict, and negativity, on children’s loneliness, internalizing, and delinquent behavior problems. The participants included 100 families with children who were between 8 and 10 years old. The families had a sibling dyad in which the target child had MR (n = 36), an LD (n = 43), or was typically developing (n = 21), while siblings were typically developing. Parents, target children, and siblings completed questionnaires and interviews assessing family and peer relationships. Sibling dyads completed a video-taped interaction. Results indicated that, as predicted, children with an LD or MR experienced significantly lower rates of positive peer experiences and significantly higher rates of negative peer experiences than did typically developing children. They exhibited significantly higher rates of loneliness and internalizing, but not delinquent, behavior problems than typically developing children. There was only partial support for the hypothesized protective effects of siblings on children’s development of adverse peer experiences. In particular, there was an indirect effect of one form of social competency training: social involvement mediated the effect of learning disabilities on adverse peer experiences. As predicted by the buffering hypothesis, emotional supportiveness by siblings moderated the impact of negative peer experiences on children’s internalizing and delinquent behavior problems. In addition, negativity within the sibling relationship moderated the effect of negative peer experiences on children’s internalizing problems while sibling conflict moderated the effect of positive peer experiences on loneliness. There were no significant effects for sibling warmth and positivity. Findings that siblings of children with MR or an LD can buffer some of the harmful effects of adverse peer experiences on psychological well being in specific instances suggest that including siblings in interventions aimed at improving peer experiences and psychological functioning may be relevant under certain circumstances.


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Psychology Commons