A Piagetian perspective on mathematical construction

In this paper, we offer a Piagetian perspective on the construction of the logico-mathematical schemas which embody our knowledge of logic and mathematics. Logico-mathematical entities are tied to the subject's activities, yet are so constructed by reflective abstraction that they result from sensorimotor experience only via the construction of intermediate schemas of increasing abstraction. The ‘axiom set’ does not exhaust the cognitive structure (schema network) which the mathematician thus acquires. We thus view ‘truth’ not as something to be defined within the closed ‘world’ of a formal system but rather in terms of the schema network within which the formal system is embedded. We differ from Piaget in that we see mathematical knowledge as based on social processes of mutual verification which provide an external drive to any ‘necessary dynamic’ of reflective abstraction within the individual. From this perspective, we argue that axiom schemas tied to a preferred interpretation may provide a necessary intermediate stage of reflective abstraction en route to acquisition of the ability to use formal systems in abstracto.     

Converging operations on a basic level in event taxonomies

Research on object concepts has identified one level of abstraction as "basic" in cognition and communication. We investigated whether concepts for routine social events have a basic level by replicating the converging operations used to investigate object concepts. In Experiment 1, subjects were presented with event names from a taxonomy and were asked to list the actions comprising the event. Many more actions were listed at the middle than at the highest taxonomic level, without a further increase at the most specific level, paralleling the pattern of superordinate-, basic-, and subordinate-level object concepts. From these action lists, brief stories were composed for each event. In Experiment 2, subjects made pairwise similarity judgments on the stories. The mean similarity of events increased with specificity, as expected. But differentiation of categories (within-category similarity compared to between-category similarity) was highest for super-ordinates, contrary to results with object categories. In Experiment 3, subjects were fastest in recognizing actions as belonging to events named at the basic level. In Experiment 4, subjects predominantly chose basic-level terms to name stories. We conclude that event taxonomies do show basic-level structure, albeit a less sharply defined and less stable structure than in object taxonomies. The benefits and hazards of extending models of object concepts to other entities, such as social events, are discussed.     

Affective influences on individual and group judgments

Do emotional states influence the social judgments made by groups and individuals? Based on affect-cognition theories and research on group judgmental shifts, we predicted that group discussion will enhance positive mood effects on judgments, but inhibit affectively-based distortions in dysphoric moods. Positive, neutral and negative moods were induced using audiovisual presentations. Individual and group consensus judgments of nine person categories on three judgmental dimensions (evaluation, competence and self-confidence) were obtained in two experimental sessions separated by a two-week interval. Results showed that individuals made more positive judgments when happy, and more negative judgments when sad than did controls. Group discussion resulted in a further polarization of positive judgments, and the attenuation of negative judgments. The findings are interpreted as evidence for the important role affect plays in mediating both individual cognitive processes and interactive social behaviours. The implications of the results for contemporary affect-cognition theories and models of group behaviour are considered.     

An on-line assessment of causal reasoning during comprehension

Fletcher and Bloom (1988) have argued that as readers read narratives, clause by clause, they repeatedly focus their attention on the last preceding clause that contains antecedents but no consequences in the text. This strategy allows them to discover a causal path linking the text's opening to its final outcome while minimizing the number of times long-term memory must be searched for missing antecedents or consequences. In order to test this hypothesis, we examined the reading times of 25 subjects for each clause of eight simple narrative texts. The results show that: (1) causal links between clauses that co-occur in short-term memory (as predicted by the strategy) increase the time required to read the second clause; (2) potential causal links between clauses that never co-occur in short-term memory (again as predicted by the strategy) have no effect on reading time; and (3) reinstatement searches are initiated at the end of sentences that are causally unrelated to the contents of short-term memory or that contain clauses that satisfy goals no longer in short-term memory. These results support the claim that subjects engage in a form of causal reasoning when they read simple narrative texts.     

The role of compliance in hypnotic and nonhypnotic analgesia

We modified the standard procedure for administering finger pressure pain in order to assess the extent to which subjects biased their reports of pain reduction when exposed to compliance-inducing instructions. Experiment 1 used only highly hypnotizable subjects and found that compliance-induced reductions in reported pain were about half as large as the reported reductions produced by hypnotic analgesia suggestions. Experiment 2 used low as well as high hypnotizables and administered hypnotic or nonhypnotic analgesia instructions and compliance instructions to the same subjects on separate pain trials. Reported pain reductions produced by hypnotic and nonhypnotic analgesia suggestions and those produced by compliance instructions were substantially and significantly correlated. Furthermore, hypnotizability correlated with compliance-induced reported pain reductions as highly as it correlated with the reported reductions produced by hypnotic analgesia suggestions. Among high hypnotizables (but not low hypnotizables) compliant responding was predicted by social desirability. The findings of both studies indicate that compliance strongly influences the reports of hypnotic and nonhypnotic analgesia proffered by high hypnotizables. The role of compliance in the pain reductions reported by low hypnotizables is less clear-cut.     

Bilingual language processing after a lesion in the left thalamic and temporal regions. A case report with early childhood onset.

This case study concerns an 18-year-old bilingual girl who suffered a radiation lesion in the left (dominant) thalamic and temporal region when she was 4 years old. Language and memory assessment revealed deficits in auditory short-term memory, auditory word comprehension, nonword repetition, syntactic processing, word fluency, and confrontation naming tasks. Both languages (English and Dutch) were found to be affected in a similar manner, despite the fact that one language (English) was acquired before and the other (Dutch) after the period of lesion onset. Most of the deficits appear to be related to verbal (short-term) memory dysfunction. Several hypotheses of subcortical involvement in memory processes are discussed with reference to existing theories in this area.     

Pattern of language impairment is different in Alzheimer's disease and multi-infarct dementia.

Language impairment was assessed in 33 patients with Alzheimer's disease (AD), in 52 patients with multi-infarct dementia (MID), and in 86 elderly community residents. The investigation included the D-Test Battery based on the Luria's Neuropsychological Investigation for all subjects. An extended battery of Luria's language items was used for 30 demented patients (11 AD and 19 MID patients) and 86 controls. The changes in language functions in normal subjects could be clearly differentiated from those seen in patients with mild dementia. The patients with different degrees of dementia differed also significantly from each other in regard to language impairment. Moreover, patients with AD and MID appeared to have different patterns of language impairment although the severity of dementia and the levels of orientation, mnestic, and conceptual functions were equal. AD was associated especially with a defect in understanding of grammatical structures and MID with disorders in recognition of words, naming, and repetition. The differential diagnostic capacity of 23 selected language items proved to be 97% between AD, MID, and control subjects. The results indicate that the examination of language functions is valuable in the differential diagnosis of dementia.     

Aphasia in left-handers. Comparison of aphasia profiles and language recovery in non-right-handed and matched right-handed patients.

The present retrospective analysis reports two studies. In Study 1, clinical aspects of aphasia are compared in right-handed (RH) and non-right-handed (NRH) patients; in Study 2, recovery from aphasia is compared in RH and NRH aphasic patients with a minimum of 5 months of daily language rehabilitation. From a continuous series of 1200 brain-damaged subjects, 24 NRH patients with a vascular lesion documented by computerized tomography were selected. In 19 cases the lesion was in the left hemisphere and in 5 cases in the right hemisphere. For 14 NRH patients, a RH subject with similar lesion, matched for age, education, length of illness, etiology (ischemic vs. hemorrhagic), and, when possible, sex was found. Presence and type of aphasia were compared in the two patients of the same pair and were found similar except for Pair 14; the RH subject had global aphasia and the NRH had conduction-like aphasia. Fifteen NRH patients were rehabilitated and reexamined at least 5 months after the first examination. Recovery of the 12 patients with a left-hemisphere lesion was compared with recovery of a group of RH subjects and no significant differences were found. Recovery of the three patients with right-hemisphere lesions is described. It is concluded that differences in type of aphasia and recovery between RHs and NRHs have been overemphasized in the past and must be reconsidered.     

Changes in information as a function of a culturally appropriate smoking cessation community intervention for Hispanics

Tested a 7-month, media-based, community intervention among Hispanics in San Francisco designed to change levels of information on the damaging effects of cigarette smoking and on the availability of culturally appropriate cessation services. Three community-wide surveys of Hispanics were conducted with independent random samples, two as baselines (n = 1,660 and 2,053) and one postintervention (n = 1,965). Results showed that changes in the level of awareness of cessation services had taken place after implementation of the intervention. Furthermore, those changes took place primarily among the less acculturated Spanish-speaking Hispanics who were the target of the intervention. The changes in information reported here demonstrate that a culturally appropriate information dissemination campaign that utilizes multiple channels can produce changes in a community's level of information even when the campaign is implemented for a relatively short period.     

The predictive validity of teacher nominations: A five-year followup of at-risk youth

The purpose of this study was to examine the predictive validity of a teacher nomination procedure for identifying at- risk children. Two hundred and twenty-five children were nominated by their teachers as well- adjusted (n= 75), socially withdrawn (n=76), or socially aggressive (n=74) during the fourth grade. Five years later, 198 of these children (88%) were located and their adjustment evaluated. Significant differences among the nominated children were found on a variety of measures, including academic grades, sociometric status, and social behavior. In addition, differences in school dropout and delinquent offenses were noted. Results are discussed in terms of the validity of teacher nomination procedures and their utility in identifying at- risk youth.