This research synthesis examines 77 reports that have manipulated psycholinguistic variables across contrasting groups in word naming and/or lexical decision tasks. Studies using adult samples and child samples are compared for the generation of appropriate predictions and informative priors for a future study focussing upon unskilled young people and adults.

Using a random-effects model, meta-analysed effect sizes (Pearson’s r and odds ratios) for frequency, length, consistency, neighbourhood size, age-of-acquisition, imageability and concreteness range from moderate to large for response time and accuracy data. Ability and age measures were also collected as group contrast measures.

For lexical decision accuracy scores, the trend was for adults to show stronger effect sizes. In word naming tasks for accuracy, children tended to show stronger effect sizes. For response time data across both tasks, children also tended to show stronger effect sizes.
Adult accuracy appears to be more dependent upon phonological and orthographical properties than semantics properties, however, semantic properties appear to play a role in response times. Whereas semantic properties of words show a stronger effect in child samples for both accuracy and response time across word naming and lexical decision.

The results of this analysis need to be treated with caution: confidence intervals are wide and accompanying heterogeneity statistics show very high values. Differences in experimental design, sample selection and choices for statistical analysis may all serve to inflate the summary effect sizes. Going forward, methods for treating this inflation are suggested and protocols to systematically reduce the heterogeneity are discussed.