Emphasis as a prompt for verbal imitation

Four- and five-yr-old disadvantaged children were read sentences composed of varying numbers of short phrases. The children were asked to repeat each sentence, but the accuracy of their imitations was not differentially reinforced. The teacher stressed (emphasized) certain words as she read each sentence. The proportion of words that were stressed was systematically varied. In general, the children imitated only parts of most sentences. Stress was effective in influencing which parts of a sentence the children would imitate, but only when relatively few words were stressed. Stressing a word increased the probability of a child's imitating that word (and, to a large extent, the entire phrase containing that word) as an inverse function of the proportion of the words that were stressed.     

Effect of contingent and non-contingent social reinforcement on the cooperative play of a preschool child

The effect of adult social reinforcement on the cooperative play of a five-year old girl in a preschool setting was assessed under two conditions: (1) presented randomly throughout the school day, and (2) presented contingent on cooperative play. Only in the latter condition was a significant change in cooperative play observed.     

On some determinants of choice in pigeons

A pigeon's pecking at each of two or three simultaneously available red keys was reinforced at different frequencies with a conditioned reinforcer, an orange key, on which 25 pecks resulted in a presentation of grain. Pecking was occasionally punished with a period of no reinforcement during which each key was dark. Both with two and with three keys, the relative frequency of pecking on a key was equal to the relative frequency of reinforcement obtained by pecks on that key. Also, the absolute frequency of pecking on each key was a linear function with zero intercept of the absolute frequency of reinforcement associated with that key. The slope of this function varied with the number of available keys; it was steeper with two than with three. The relative frequency of switching from any key (two successive pecks on different keys) approximated a linear function with zero intercept and slope slightly greater than 1.0 of the total relative frequency of reinforcement associated with the keys to which the bird could switch. However, the relative frequency of switching to a particular key often showed systematic irregularities. The invariance in these data is the equality between the relative frequency of pecks on one of two or three keys and the relative frequency of reinforcement associated with that key.     

Moral absolutism and abortion: Alan Donagan on the hysterectomy and craniotomy cases

Reynolds argues that the nonconsequentialist moral theory proposed by Alan Donagan in his book The Theory of Morality (University of Chicago Press; 1977) does not resolve the cases in which craniotomy or removal of a cancerous uterus appears necessary to save the life of a pregnant woman. Donagan's absolute prohibition against the murder of the innocent and his rejection of the principle of double effect have led him to view the fetus as a pursuer or assailant or to assert the theory of proleptic agreement--that in risk taking ventures the parties may agree that killing one person to save the lives of the others will be accepted. Reynolds holds these arguments to be inapplicable in therapeutic abortions involving craniotomy or hysterectomy and concludes that Donagan's absolutist theory must be reexamined.