A direct comparison of four methods for eliminating a response

Thirty-two rats pressed one lever (lever A) on a VI 30-sec schedule of food reinforcement and were then shifted to one of four procedures for eliminating the lever A response: extinction, differential reinforcement of other behavior, reinforcement of a different response (pole pushing), and reinforcement of a similar response (pressing lever B). Effectiveness of a response-elimination procedure was measured by (1) how quickly lever A response rate fell to a low level when the procedure was in effect, (2) how much lever A responding recovered when the procedure was discontinued, and (3) how resistant lever A responding was to reinstatement when the VI reinforcement schedule was reimposed. No one method was superior by all three measures. Extinction produced the most variable behavior, while differential reinforcement of other behavior produced the least. Reinforcing alternative behavior produced the greatest recovery in the original lever A response when the response-elimination procedure was discontinued.     

Encoding strategy and sensory and semantic interference

Studies were designed to compare the effects of encoding strategies on two types of interference, sensory and semantic. Paired-associate lists were learned under instructional sets encouraging interactive imagery or repetitious rehearsal. Sensory interference was created by mispairing rhymes and semantic interference was produced by mispairing associatively related words. In control lists word pairs were unrelated. The results indicated that encoding strategy did not influence amounts of sensory and semantic interference. Mispairing rhymes produced the same amount of confusion as mispairing associates whether pairs were encoded through interaction imagery or through repetitious rehearsal. These effects were found with both short and long encoding intervals. The findings are inconsistent with the idea that encoding operations or strategies applied to word pairs completely determine the type of code activated for those pairs. Both sensory and semantic codes appear to be activated under each kind of encoding strategy.     

Alleviation of narcotic withdrawal syndrome by conditional stimuli

We systematically paired auditory, olfactory, and social stimuli with each injection of morphine in rats. We found that, when morphine was kept constant at a low dose, the external stimuli acquired the property of a conditional stimulus (CS) to cause hyperthermia which was antagonized by naloxone. In rats in which morphine doses were regularly increased to cause morphine dependence, the CS presented during withdrawal, caused reduction in withdrawal signs (wet shakes, hypothermia, aggression) and produced hyperglycemia as well as elevation of striatal homovanillic acid. CS-induced alleviation of withdrawal hypothermia was blocked by mecamylamine, phenoxybenzamine, haloperidol, benztropine or naloxone but not by cyproheptadine or propranolol.     

Some attributes of adjectives used by young children

Analysis of 24 spontaneous speech samples from children at 24 and 30 months revealed a correlated progression in the form, function and meaning of modifiers used with increased language development. Predicate adjectives were used to comment on transitory states of objects and predominated in the early speech samples. Attributive adjectives were used to subdivide classes or to specify among particular instances within classes on the basis of physical characteristics such as size, by use of a conventional type name, or by use of a possessive. Attributives predominated in the later speech samples. Differential use of a particular form appears to be a function of its cognitive and communicational usefulness rather than its syntactic derivation.