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6 MILLET ET AL.Downloaded By: [Millet, Xavier] At: 10:57 4 November 2009Figure 2. Estimated effect sizes (and 95% CIs) of priming scores between Alzheimer’s disease (AD) patients and elderly control groups.Note: Area of the squares is proportional to the study statistical weight in the overall effect size.Comparison of word-stem priming between ADpatients and elderly controls for each encodingconditionIn the third set of analyses, we were interested in comparingword-stem completion priming performancesbetween AD patients and elderly controls within eachencoding condition. Several subsets of studies were consideredaccording to the encoding instructions providedto participants. Significant heterogeneity between thestudies was encountered for each analysis (Q values arereported Table 2). For each encoding condition, we estimatedthe effect size between priming performances of ADpatients and those of elderly controls groups (Table 2).Forest plots showing the effect sizes and 95% CIs foreach encoding condition are displayed in Figure 3.For the studies involving an encoding conditionrequiring participants to generate a word (Fleischmanet al., 1999; Fleischman et al., 1997; Grosse et al., 1990),the meta-analysis was conducted on a total of 131 ADpatients and 96 elderly controls and yielded a trivialeffect size (–0.06, CI 95% [–0.51; 0.40]). Priming performanceswere not significantly different between thetwo groups.A single study involved an encoding condition requiringparticipants to make semantic judgments (BeauregardTABLE 2Effect sizes and 95% confidence intervals between AD and elderly participants’ primingperformances for each encoding conditionStudies(n)Pooledeffect sizes Q 95% CI p valueRead 7 −0.45 9.50 −0.75 −0.16