Comparison of the performances of a fluent and a nonfluent aphasic on a pantomimic referential task

The pantomimic performances of a typical Broca's (nonfluent) and Wernicke's (fluent) aphasic were compared with each other and with four normal control subjects on a simple task of nonverbal referential communication. Both aphasic subjects demonstrated only about 50% accuracy in their pantomimic communication. Also, measures were obtained of the motoric fluency of the pantomimes of all subjects and comparisons were made between the fluent and nonfluent aphasics. These measures demonstrated distinct differences in the fluency patterns of the pantomimes of the two aphasic subjects similar to the differences in speech fluency which distinguish and characterize these two types of aphasia; that is, the fluent aphasic pantomimed fluently and like the control subjects and the nonfluent aphasic pantomimed nonfluently. The quantitative and qualitative similarities in the fluency patterns of the speech and the pantomimic behaviors of the aphasic subjects are discussed in terms of their implications for a definition of aphasia.     

The onset of stuttering following drug overdose

Recently, some attention has been focused on acquired stuttering, disfluencies that begin in adulthood. The nature of acquired stuttering differs in several respects from developmental stuttering. A case of acquired stuttering following drug overdose is presented and contrasted with previously reported cases. The case is noteworthy in that, while many characteristics of acquired stuttering are evidenced, several symptoms associated with developmental stuttering are also observed. The findings are discussed in terms of a possible link between developmental and acquired forms of stuttering.     

Facing up to the issues: Reply to Hellige (1983)

In a recent article in this journal, Hellige (Brain and Cognition, 2, 199-203, 1983) presented a critique of the chimeric-face technique that was used by us to validate a hand preference questionnaire. Data were presented by Hellige to show that the left visual field (LVF) bias that occurs on this task is due primarily to differences in detail in the features of the two faces and not because of right hemisphere dominance for face perception. In our rebuttal, we acknowledge that the two faces are not mirror-image duplicates of each other, but contend that this fact does not explain why differences between left-handers and right-handers have been observed on this task. Further data on the role of handedness as well as other variables impacting on this task are presented. A possible explanation is also offered for the rather small extent of LVF bias that Hellige obtained when he used corrected (i.e., true mirror-image) versions of Jaynes' chimeric faces.     

The development of procedural knowledge: An alternative explanation for chronometric trends of mental arithmetic

In a review of the Chronometrie literature, M. H. Ashcraft (Developmental Review, 1982, 2, 213–236) concluded that the development of number fact efficiency is due to a shift from relying on procedural knowledge such as counting to relying on declarative knowledge (a stored network of facts). This model assumes that all procedural processes are slow or remain slow, which is probably not the case. An alternative account posits that the key change in number fact efficiency involves a shift from slow counting procedures to principled procedural knowledge. As rules, heuristics, and principles become more familiar and interconnected, their use, for example, in producing the number facts becomes more automatic. The use of such procedural knowledge would be cognitively more economical than storing individual facts in long-term memory. Finally, existing Chronometric data can readily be interpreted in terms of this alternative model.     

Food-searching behavior of cats in a multiple-choice elimination problem

Twelve cats were individually exposed to a four-point elimination problem for 50 consecutive days. The problem for the animals consisted of choosing a series of different points where they found, and were allowed to eat, a piece of meat, without returning to any previously visited point. The order of elimination was not controlled in any way by the experimenter. Results indicated that cats were able to solve this problem. All subjects showed a strong tendency to make successive runs toward points situated as far apart as possible. Moreover, a relation was shown between performance and the tendency to follow this high divergence principle. This result is discussed in terms of subjects' ability to process information about the spatial characteristics of the experimental situation. This ability might in fact be related to the behavioral plasticity of animals in spatial problems according to the difficulty of the task.     

Children's comprehension of complex sentences

Four tasks were given to children from 4–12 to test their comprehension of complex sentences containing main verbs taking underlying sentences as their complements (Sally knew that she was early). In an imperatives task, very young children interpreted only the complement verb and ignored the complex verb. In a short-term memory task, sentences with two negations usually lost the second not in recall. In direct questioning and anomaly-detection tasks, children tended to make pragmatic inferences and excessively depend on knowledge about the world, as opposed to linguistic information. Overall results showed that even sixth graders had not yet attained adult-level comprehension of complex sentences.     

Persistence of response prevention effects following retraining of escape behavior

This study evaluated the effects of response prevention procedures on the extinction of escape behavior following the reinstatement of shock-escape training prior to the start of extinction. Female hooded rats were assigned to four groups (N = 10) in a factorial design which orthogonally combined response prevention or pseudo-prevention procedures with escape retraining or no retraining procedures. Results showed that prevention reliably impaired shock-escape behavior on early retraining trials; but this effect dissipated completely by the end of retraining. In extinction, prevention reliably facilitated the extinction of escape behavior relative to that of pseudo-prevention controls; but the degree of facilitation was reliably attenuated by retraining procedures. These findings were related to the competing response interpretation of prevention effects.     

Nest material and food as reinforcers for fixed-ratio responding in mice

Three experiments investigated the importance of operant-reinforcer distance as a factor affecting continuous reinforcement (CRF) and fixed-ratio (FR) performance in mice, with nest material and food as reinforcers. In Experiment 1, nest material (paper strips) was presented on a series of FR schedules of increasing size, with the operandum located as close as possible to the reinforcer dispenser. Subjects compensated for increases in FR size by proportionately increasing their response output, but ratio strain occurred at low FR values. In Experiment 2, response rate was found to be inversely related to operant-reinforcer distance on a CRF schedule with nest material as reinforcer. In Experiment 3, food was presented on a series of FR schedules at two levels of deprivation, and with three operant-reinforcer distances. Operant-reinforcer distance was found to affect CRF response rate, degree of compensation for increases in FR size, and occurrence of ratio strain, but only when deprivation level was low. The results support the view that nest material and food share fundamentally similar reinforcing properties, but that nest material is a weaker reinforcer under normal test conditions.