The influence of reward on comprehension testing of 2-year-old children.

A procedure was devised in which a reward was hidden under the stimulus picture representing the correct answer to a comprehension task. Both accuracy and test-retest reliability of the responses of 34 2-yr-old children were measured. Eight items tested comprehension of plural allomorphs /s/ and /z/, and eight evaluated the comprehension of word order in reversible subject-verb-object active sentences. The effects of the rewarded search procedure varied, depending on sex and the language structure that was tested. In those cases where the procedure significantly affected responses, the difference was in the direction of improved accuracy and reliability.