Three white rats, aftcr 50 continuous reinforcements, were exposed successively, under dim illumination, to reinforcement delays of 1, 3, 5, 7.5, 10, 15, and 20 sec, with prolonged training at the 20-sec level. Behavior was maintained at each level, and an increase in interval was accompanied by an increase in post-reinforcement pause. Subsequently, under both 20-and 30-sec delays, the animals were tested during half of each daily session to determine the effect of introducing darkness during each delay interval. The result of this stimulus "support" was to regularize and increase response rate for each animal at both interval values.

In a recent attempt to translate several papers for Brazilian publication, the present writers were confronted with the problem of selecting suitable Portuguese equivalents of terms commonly used in English-language studies of operant behavior. We felt a special responsibility in this task since, to our knowledge, there were no more than one or two instances of such terminology in this country (e.g., Rocha e Silva, 1961). We were bandeirantes (= pioneers) in the field! Many items in the present tentative list of translations were the result of our attempt. Others came after we had consulted the papers on French and German translations (Richelle, 1960;Schaefer, 1960)