On the study of statistical intuitions

The study of intuitions and errors in judgment under uncertainty is complicated by several factors: discrepancies between acceptance and application of normative rules; effects of content on the application of rules; Socratic hints that create intuitions while testing them; demand characteristics of within-subject experiments; subjects' interpretations of experimental messages according to standard conversational rules. The positive analysis of a judgmental error in terms of heuristics may be supplemented by a negative analysis, which seeks to explain why the correct rule is not intuitively compelling. A negative analysis of non-regressive prediction is outlined.     

The development of alertness

Two experiments explored variation in the alerting process across age and warning interval as well as the effects of alertness on subsequent processing. Experiment 1 obtained alertness functions for a group of 5-year-olds, 8-year-olds, and adults. Results revealed strong age differences in speed of alerting and in maintenance of alertness over a 1-sec interval. Five-year-olds alerted more slowly than older groups and sustained optimal alertness less well. Both groups of children showed more variability in alerting functions compared with adults. Experiment 2 examined the degree to which age differences in processing speed were attributable to differential speed and maintenance of alerting. Masking functions obtained across variations in the alerting interval revealed that when level of alertness was optimal in both 5-year-olds and adults, minimal age differences in processing speed were observed. During short, nonoptimal alerting intervals, speed of processing in adults was faster than in 5-year-old children. The pattern of results across studies suggested that alertness can fluctuate over time in young children, that level of alertness affects subsequent perceptual processing speed, and that developmental variation in speed and maintenance of alertness can partly explain observed age differences in processing speed. The potential role of alertness in more complex cognitive tasks is discussed.     

The development of spatial understanding in infancy

This paper examines the development of spatial understanding between 8 and 24 months. In particular, it examines whether young infants code changes in the position of an object or themselves in geographic or egocentric terms. The infants sat in a baby chair which was attached to a circular table in such a way that either the infant could be rotated around the edge of the table or the table-top itself could be rotated. Rotation of infant or table could be performed independently or simultaneously. Infants were shown an object which was then hidden under one of either two or three identical cups sitting on the table. Before the infant was allowed to search for the toy, either the table, the infant, or both were rotated, a procedure which resulted in an invisible displacement of the object in terms of geographical and/or egocentric spatial position. Rotations of 60, 90, 120, and 180° were used. Three groups of infants were tested, one cross-sectional (12–24 months), one longitudinal (12–24 months), and one consisting of a group of infants already known to be accelerated in object concept development (8–20 months). The cross-sectional results indicated that egocentric responding continues well into the second half of the second year of life. Even with fortnightly exposure to the tasks, egocentric responding was still evident in some longitudinal babies as late as 19 months. The results of the accelerated group suggest that acceleration through the sequence of object concept development facilitates development of spatial understanding in a wider sense, that is, in the sense of understanding the interrelation of positions in space. The implications of these results for competing theories of the source of object concept errors are discussed.     

Communicative gestures of the hand and arm when 4-year-old sons and their mothers interact

This study investigated a wide range of communicative hand/arm gestures of 4-year-old males when interacting with their mothers. The types of gesture categories observed were in keeping with the predicted encoding ability of this aged child. Pantomimic and deictic gestures were observed in significantly greater numbers than semantic modifying and relational gestures. Although it was found that the mothers' gestural usage reflected the type of gesture categories seen in the children's group, no correlation was found between gesture usage of individual mother-child pairs.     

Alternate antagonism with paradoxical translation behavior in two bilingual aphasic patients

Two patients presenting a pattern of recovery yet unreported in the literature were observed, one in Paris, the other in Montreal. Both patients alternately suffered severe word-finding difficulties in one language while remaining relatively fluent in the other. They retained good comprehension in both of their languages at all times. They were able to translate correctly and without hesitation from the language they could speak well at the time into the language unavailable for spontaneous use, but were unable to translate from their temporarily poor language (which they understood well) into the language which they could speak quite well at the time.     

Developmental differences in the allocation of processing capacity

Recently psychologists have formulated a comprehensive view of attention involving allocation of processing capacity. Although developmental changes in processing capacity have been proposed as one source of age differences in certain cognitive skills, there has been little systematic investigation of this hypothesis. In the present study, second and sixth graders and adults (8, 12, and 20 years of age, respectively) performed a letter-matching task (primary task) concurrently with an auditory detection task (secondary task). Changes in reaction time in the secondary task as a function of manipulations of the primary task were used to estimate capacity allocation to the primary task. Primary task variables included stage of processing (alerting, encoding, rehearsing, responding) and matching condition (physical-identity vs name-identity matching). Age differences in secondary task performance were found to be related to stage of processing but not to matching condition. Earlier stages of the letter match task (alerting, encoding) required somewhat more capacity allocation in younger subjects. Later stages (rehearsing, responding) made substantially higher demands on capacity in children. Capacity allocation may be an important cognitive variable mediating developmental differences in basic information processing skills, and may underlie age trends found in performance of certain complex cognitive tasks.     

Levels in the identifying of orientation by preschool children

A new approach to understanding the perception of orientation proposes that the first level in the processing of orientation information results in perceiving whether a shape is upright or nonupright; nonupright orientations are not distinguished from each other. As predicted, children of 3 and 4 years discriminated upright from nonupright pictures more readily than they discriminated the nonuprights (upside down and sideways) from each other. The angular differences between the pairs of discriminanda (whether 90 or 180°) had no effect on performance. the difficulty of distinguishing between nonuprights could not be attributed simply to a lack of attention to the dimension of orientation. The theory appears to have considerable generality, and provides a basis for understanding (1) perception of the orientation of both realistic and geometric shapes, and (2) similarities in orientation perception observed between children and adults.     

Semantic aphasia: A neglected entity

Three cases of semantic aphasia are reported. Computerized brain tomography showed bilateral temporo-parieto-occipital junction hemorrhages in one patient, and left parieto-occipital junction infarctions in the other two patients. The auditory comprehension defect of the three patients was characterized by preserved understanding of single words and impaired understanding of grammatically complex constructions. It is suggested that this comprehension defect reflects an inability to fully grasp the meaning of words and grammatical constructions imbued with spatial or quasi-spatial significance. Each of the three patients showed a complex spatial disorder that included constructional apraxia, spatial agnosia, and elements of Gerstmann's syndrome. The aphasic as well as the spatial disorder of semantic aphasics may be manifestations of a common defect in the perception of spatial relationships produced by left temporo-parieto-occipital region damage.