title: A quantitative review of overjustification effects in persons with intellectual and developmental disabilities.
abstract: The overjustification hypothesis suggests that extrinsic rewards undermine intrinsic motivation. Extrinsic rewards are common in strengthening behavior in persons with intellectual and developmental disabilities; we examined overjustification effects in this context. A literature search yielded 65 data sets permitting comparison of responding during an initial no-reinforcement phase to a subsequent no-reinforcement phase, separated by a reinforcement phase. We used effect sizes to compare response levels in these two no-reinforcement phases. Overall, the mean effect size did not differ from zero; levels in the second no-reinforcement phase were equally likely to be higher or lower than in the first. However, in contrast to the overjustification hypothesis, levels were higher in the second no-reinforcement phase when comparing the single no-reinforcement sessions immediately before and after reinforcement. Outcomes consistent with the overjustification hypothesis were somewhat more likely when the target behavior occurred at relatively higher levels prior to reinforcement.
authors.affiliation: The Kennedy Krieger Institute and University of Maryland, Baltimore County.
authors.forename: Allison
authors.initials: A
authors.lastname: Levy
authors.affiliation: University of Florida.
authors.forename: Iser G
authors.initials: IG
authors.lastname: DeLeon
authors.affiliation: University of Florida.
authors.forename: Catherine K
authors.initials: CK
authors.lastname: Martinez
authors.affiliation: University of Florida.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fernandez
authors.affiliation: University of Florida.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Gage
authors.affiliation: The Icelandic Centre for Research - RANNÍS.
authors.forename: Sigurdur Óli
authors.initials: SÓ
authors.lastname: Sigurdsson
authors.affiliation: The Kennedy Krieger Institute and University of Maryland, Baltimore County.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Frank-Crawford
mesh_terms: D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D002658:Developmental Disabilities / Q000523:psychology*; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000523:psychology*; D007389:Internal-External Control; D008297:Male; D009042:Motivation / Q000502:physiology*; D012054:Reinforcement, Psychology
keywords: extrinsic reinforcement; intellectual and developmental disabilities; intrinsic motivation; overjustification effect