5 albino rats (adjusted percentage: AP) held at 80% of normal body weight of 25 Ss maintained on ad-lib, food and water (criterion) were compared with 5 Ss maintained at 80% of their individual predeprivation weight (fixed percentage: FP) and 5 Ss fed for 30 min. every 24 hr. (fixed interval: FI). Predictions based on an assumed artifact due to failure to account for normal body growth under FP and FI were confirmed. Lever-press rates under a VI-2-min. reinforcement schedule gradually increased under FP and FI as body weight (percentage of criterion Ss) decreased, whereas AP Ss maintained constant-response rates. Interchanging AP and FP deprivation schedules resulted in response rates consistent with weight levels assumed under new schedules.

Current research in verbal learning is reviewed in terms of its implications for developmental research. Suggestions are provided which relate to the methodology of research incorporating age as a treatment variable in addition to highlighting the analytical utility of verbal learning paradigms in the study of developmental learning processes. The similarities of theory and data relating to nonverbal tasks (e.g., probability-learning, transposition, reversal-shift, and discrimination-learning paradigms) and to theory concerning the interaction of verbal learning and development are also discussed.

The methodological adequacy of the work considered as experimental tests of the Taylor-Spence drive theory is examined. Pertinent research involving verbal learning (serial, paired-associate, and transfer) paradigms is reviewed in the context of recent methodological and theoretical developments in verbal learning. Sources of potential confounding are highlighted in addition to suggested refinements in methodology which permit more adequate tests of the Taylor-Spence theory.

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