Retention of verbal information by rehearsal in relation to the fluency of verbal output in aphasia

The purpose of the present study was to determine if aphasic subject groups differentiated by the fluency of their verbal output employed rehearsal as a strategy for maintaining verbally coded information in primary memory. A task based upon the Brown-Peterson paradigm was administered to 10 fluent aphasic patients, 10 nonfluent aphasic patients, 10 right-brain-damaged patients, and 10 nonneurological patients. The findings indicate that the nonfluent aphasic patients did not rehearse the verbal information while the fluent aphasic, right-brain-damaged, and nonneurological patients did rehearse. In addition, both fluent and nonfluent aphasic patients encoded significantly less information into the memory system initially and performed worse on the task overall than right-brain-damaged and nonneurological patients.     

Concurrent validity of the WISC-R factor scores

This study investigated the efficacy of predicting academic achievement as measured by the Wide Range Achievement Test using the factor scores of the Wechsler Intelligence Scale for Children-Revised as potential predictors. Both instruments were administered to 200 school children referred for psychological evaluations. Factor scores for the WISC-R were computed according to equations provided by Gutkin (1978). These factor scores then were regressed in a stepwise manner on the Reading, Spelling, and Arithmetic standard scores from the Wide Range Achievement Test. Stepwise regressions also were performed using the traditional Verbal and Performance IQs as the potential predictors. A comparison was made between the results obtained by use of the factors or the more common scores. The results indicated that the Freedom From Distractibility factor score significantly aided in the prediction of Reading and Spelling achievement and was of primary importance in predicting Arithmetic achievement. When the stepwise results using the different scores were contrasted, the factor scores accounted for appreaciably more variance in Arithmetic than did the traditional Verbal and Performance IQs. Derived regression equations are reported along with a discussion of the interpretability of the Freedom From Distractibility factor.     

The development of discourse mapping processes: the on-line interpretation of anaphoric expressions

The present research focuses on how children integrate the antecedent of different kinds of anaphor into their on-going interpretation of an utterance, and on the kinds of cues they use to help them to do this. These issues were studied by examining the on-line processing of three types of anaphoric devices—repeated noun phrases, general terms and pronoun anaphors. The data showed that by the age of five, anaphoric mapping processes in general are well-mastered, although all age-groups (5, 7, 10 year olds and adults) found general term anaphors more difficult to interpret. The major developmental differences concerned the processing of anaphoric pronouns. For five year olds, pronouns were primarily interpreted as devices which maintained the thematic subject of the discourse, but when there was no thematic subject they relied primarily on pragmatic plausibility in their assignment of pronominal co-reference. As children get older, they are able to take advantage of the lexical properties of pronouns and all three sources of information—lexical, pragmatic inference and the thematic structure of the discourse—play contributory roles in the assignment of reference to a pronoun.     

Discrete dynamic choice: An extension of the choice models of thurstone and luce

The present paper deals with the extension of two well-known static discrete choice theories to the dynamic situation in which individuals make choices at several points in (continuous) time. A dynamic version of Luce's Axiom, “independence from irrelevant alternatives”, is proposed and some of its implications are derived. In the static case Yellott (J. Math. Psych. 1977, 15, 109–146) and others have demonstrated that an independent random utility model generated from the extreme value distribution exp(?e^?ax?b) becomes equivalent to Luce's Axiom. Yellott also introduced an axiom called “invariance under uniform expansions of the choice set”, and he proved that within the class of random utility models with independent identically distributed utilities (apart from a location shift) this axiom is equivalent to Luce's Axiom. These results are extended to the dynamic situation and it is shown that if the utility processes are expressed by so-called extremal processes the corresponding choice model is Markovian. A nonstationary generalization is proposed which is a substantial interest in applications where the parameters of the choice process are influenced by previous choice experience or by time-varying exogenous variables. In particular, it is demonstrated that the nonstationary model is Markovian if and only if the joint choice probabilities at two points in time have a particular form. Thus, the paper provides a rationale for applying a specific class of Markov models as the point of departure when modelling mobility processes that involve individual discrete decisions over time.     

The effects of distributed training on retention of operant conditioning in human infants

Long-term retention of operant footkicking acquired in the mobile conjugate reinforcement paradigm was assessed as a function of the distribution of training time. In the first study, 3-month-old infants were trained for either one 18-min session or for two 9-min or three 6-min sessions separated by 24-hr intervals. All infants exhibited retention during a test administered immediately after training, but only those trained in a single session continued to perform the conditioned response during cued-recall tests 7 or 14 days later. Infants trained in three sessions showed no evidence of remembering the contingency even after a week. A warm-up decrement, seen in the day-to-day performance of infants in the distributed conditions, was eliminated in the second study by the interpolation of a nonreinforcement period at the outset of daily sessions. This procedure also enhanced long-term retention such that infants trained in three 6-min session now remembered the contingency for 14 days and did not differ from infants who had received a single 18-min session. Whether distributed training facilitates or impairs long-term retention appears to depend on the opportunity for infants to acquire a sufficient number (or kind) of effective retrieval cues during original learning.     

Discrimination and generalization by rats of temporal stimuli lasting for minutes

In three experiments, rats learned to respond differentially to reinforced and nonreinforced trials when the length of the intertrial interval (ITI) predicted the trial outcome (reinforcement or nonreinforcement). Rats in control groups, for whom the length of the ITI did not predict the outcome, did not show differential performance on nonreinforced and reinforced trials. Generalization gradients obtained following discrimination training were comparable to those obtained following discrimination training with other types of discriminative stimuli. That is, groups which had shown differential performance in discrimination training yielded generalization gradients with fastest speeds at the previously reinforced ITIs, slowest speeds at the previously nonreinforced ITIs, and intermediate speeds at ITIs of intermediate length. Control groups yielded flat gradients across all ITIs tested. These effects were shown for relative time discrimination (short time = reinforcement, long time = nonreinforcement, or the reverse) and also for an absolute time discrimination (long and short time = reinforcement, middle time = nonreinforcement or the reverse). This method was effective for time duration measured in minutes rather than seconds, as is more commonly the case.     

Stimulus control of responding by response-reinforcer temporal contiguity

The stimulus properties of brief disruptions in response-reinforcer temporal contiguity were investigated using a discrete trial conditional discrimination procedure. Key pecking (nondelay) or key pecking followed by a brief interval of nonpecking (delay) in the sample component produced a stimulus change (choice component). Pecks in the choice component to one of two alternatives resulted in food or blackout, conditional upon which response requirement was met in producing the choice component. A baseline condition, in which key pecking always produced the choice component and correct choices were arranged randomly, alternated with experimental conditions that included nondelay and delay values of either 0.2, 0.5, or 1.0 sec between the last key peck and the initiation of the choice component. All subjects accurately discriminated brief temporal delays between a response and stimulus change, with choice accuracy increasing for three of four subjects as the temporal disruption in contiguity increase. Implications of the research for the study of delayed reinforcement, response-independent reinforcement, and the discrimination of causality are discussed.     

Attentional biases and the right-ear effect in dichotic listening

Most dichotic listening experiments permit subjects to deploy attention in any way they choose. We argue that this adds uncontrolled variance to the observed right-ear advantage. In the first experiment, more robust laterality effects were obtained in an identification task with focused than with divided attention. Such differences were not found in the second experiment, when a detection procedure was used. Virtually all the laterality effect observed in the second study could be attributed to subjects who were biased attenders, in the sense that they exhibited more intrusions from the right ear to the left than vice versa. However, rather than indicating that laterality effects are simply attentional bias, this effect can be attributed to an asymmetry of perceptual discrimination.     

Aphasia following a right thalamic hemorrhage

A left-handed patient with a right thalamic hemorrhage and disordered speech is described. Sequential examinations and aphasia testing were done during a 1-year follow-up period and the results are reported. This case supports those authors who have described characteristics they feel are helpful in diagnosing disordered speech associated with thalamic lesions. Paucity of speech, reduced voice volume, anomia, some paraphasia, and severe dysgraphia were present, but comprehension and repetition were relatively preserved. She showed modest improvement with time. This case also confirms that thalamic involvement in speech is a dominant, rather than a specifically left hemispheric function.     

An observational case study of failure in social problem-solving

An observationally based assessment of social problem-solving skill was contrasted with more traditional testing methods. A preschool child with low social success was chosen for a demonstration profile analysis. The relative frequencies of the social goals, strategies, and targets shown by this child during free play were plotted in relation to that of his same-sex peer group. Parallel profiles of his relative success with specific goals, strategies, and targets were also constructed and compared to relevant group means and standard deviations. Specific social problem-solving strengths and weaknesses were identified from these profiles, using both intra- and interindividual analyses. The benefits and limitations of this approach for measurement and treatment of social problem-solving deficits were discussed.