Feedback during exposure to inescapable shocks and subsequent shock-escape performance

In two experiments, we assessed the ability of a feedback stimulus during helplessness training to reduce the performance deficits common to inescapable shock. In each experiment, four groups of rats were exposed to either escapable shock (E), inescapable shock with a feedback stimulus following shock termination (Y-FS), inescapable shock with no feedback stimulus (Y-NFS), or no shock (N). The feedback stimulus eliminated the interference effects of inescapable shock when tested with an FR-3 lever press escape task (Experiment 1) or on an FR-1 task with a 3-s delay between the response and shock termination (Experiment 2). These results suggest that stress-induced biochemical changes may mediate the interference effects seen in inescapably shocked rats.     

Tokens for stuttering

Four young stutterers were observed during 10 weekly sessions. Each session was divided into pretreatment, treatment, and posttreatment segments. Redeemable tokens were administered contingent upon stuttering behaviors in the treatment segment of the Experimental condition. In a Parallel Control condition, no tokens were administered during the entire session. The differences between the pretreatment and treatment segments were compared for the two conditions. Three subjects had dramatically fewer stuttering behaviors when tokens were being administered, while the fourth had more stuttering under the same condition. The subject whose stuttering increased had a history of therapy in which voluntary, “faked” stuttering had been called for, and the behaviors that increased were judged to be of this type. The decreases were interpreted as suggesting that the contingent tokens acted to countercondition the aversiveness of the stuttering experience, which reduced the anticipation of stuttering and hence the stuttering itself. The increase was felt to be simple reinforcement. The counterconditioning interpretation was borne out in two clinical applications in which money was presented contingent on stuttering behaviors judged to be aversive to the stutterer, and in which dramatically sudden, but long-lasting, improvement was seen.     

Cognitive task effects on hemispheric blood flow in humans: Evidence for individual differences in hemispheric activation

Evidence from two indirect measures of hemispheric activity, EEG α and conjugate lateral eye movements, has pointed to the existence of individual differences in hemispheric activation. Results from a more direct indicator of hemispheric activity, regional cerebral blood flow as measured by the ¹³³Xe inhalation method, show that such individual differences can be detected in the distribution of blood in the two hemispheres and that the amount of increase in blood flow in the right relative to the left hemisphere is correlated with performance on a spatial task. These results corroborate and extend the findings from the EEG and eye movement studies and suggest that the dimension of individual differences in hemispheric activation may exert significant influence on cognitive performance and on problem-solving strategies.     

Sensitivity to grammatical structure in so-called agrammatic aphasics

Comprehension failures in agrammatic aphasics, as well as their difficulties in sentence construction, have been attributed to an underlying deficit involving the retrieval of syntactic structure. In this study we show that four agrammatic patients display a remarkable sensitivity to structural information, as indicated by their performance on a grammaticality judgment task. These results indicate significant sparing of syntactic knowledge in agrammatism, and suggest that the sentence comprehension disturbances in these patients do not reflect loss of the capacity to recover syntactic structure. In particular, accounts of the comprehension deficit in agrammatism that implicate a failure to exploit information carried by the closed class (function word) vocabulary are called seriously into question. Alternative explanations of the comprehension problem in agrammatism are explored.     

Probabilistic contingency theories of animal conditioning: A critical analysis

Seven contingency theories of classical and instrumental conditioning were defined in relation to the contingency matrix and to six separate probabilities which can be derived from this matrix. These theories were compared on the basis of formal similarities and differences, and were judged against three separate empirical variables which have been discussed in the contingency literature: the duration of the intertrial interval, partial reinforcement, and negative contingencies between the two events of conditioning. All previous theories had some difficulty predicting the effects of one or more of these variables upon animal conditioning. Also, some formulas make the unusual prediction that there will be less conditioning when there is more than one conditioning trial. The paper concluded with an extensive discussion of the problems that are created by conditioning events with temporal extension; events which are then categorized by a contingency matrix which has no temporal character. Some possible solutions to the problems were discussed.     

The sources of developmental differences in children's incidental processing during discrimination trials

Crane and Ross reported that second graders learned more than sixth graders about attributes made relevant after solution of a discrimination task. Here two experiments are reported that enlighten the sources of this developmental difference. Both make use of an experimental technique whereby children verbalize their hypotheses during solution of a discrimination problem. The results indicate that ten-year-olds do not learn about incidental attributes that they tested while irrelevant in the pre-solution period, but that five-year-olds and seven-year-olds do. Children of all three ages process incidental information about attributes that they did not sample pre-solution. With some qualification, the incidentally processed information is retained throughout a five-minute delay interval. The results bear on developmental trends in the distribution of attention and on theoretical accounts of incidental learning in discrimination tasks.     

Individual differences in speed of phonemic analysis, visual analysis, and reading.

College student subjects (Ss) classified phrases as making sense or not according to sound in one condition, according to visual appearance in another, and in abasic task in which either strategy would yield right answers. Ss who were relatively fast in the visual condition were faster at the basic task than Ss who were relatively fast in the sound condition. Other results suggested that the former Ss used a visual strategy in the basic task while the latter used a phonemic strategy.