Extracting thresholds from noisy psychophysical data.

Psychophysical studies with infants or with patients often are unable to use pilot data, training, or large numbers of trials. To evaluate threshold estimates under these conditions, computer simulations of experiments with small numbers of trials were performed by using psychometric functions based on a model of two types of noise: stimulus-related noise (affecting slope) and extraneous noise (affecting upper asymptote). Threshold estimates were biased and imprecise when extraneous noise was high, as were the estimates of extraneous noise. Strategies were developed for rejecting data sets as too noisy for unbiased and precise threshold estimation; these strategies were most successful when extraneous noise was low for most of the data sets. An analysis of 1,026 data sets from visual function tests of infants and toddlers showed that extraneous noise is often considerable, that experimental paradigms can be developed that minimize extraneous noise, and that data analysis that does not consider the effects of extraneous noise may underestimate test-retest reliability and overestimate interocular differences.     

What learning-disabled readers fail to retrieve on verbal dichotic tests: A problem of encoding,retrieval, or storage?

Three theoretical models were assessed as a framework for capturing learning-disabled readers' faulty word retrieval. To this end, learning-disabled and skilled readers were compared on verbal dichotic listening tasks for free recall and cued recall of word lists organized by semantic, phonemic, and structural features. The results indicated that disabled readers were comparable on free recall but were inferior to skilled readers on cued recall. No ability group differences were found for categorical and noncategorical recall intrusions during the cued recall phase. Cued recall performance was further analyzed for individual differences in memory trace structure (via the Tulving & Watkins, 1975, reduction method), ear asymmetry, and the allocation of attention to word features prior to cuing. Results indicated that during the cued recall phase, disabled readers' memory traces were inferior in structure to those of skilled readers, even though the two ability groups produced comparable symmetrical recall patterns for the ear presentations. Further, disabled readers had lower selective attention scores for the interhemispheric processing of information prior to cuing than did skilled readers. Taken together, the results suggest that, prior to cued recall, disabled readers suffer from attentional difficulties during interhemispheric processing, which in turn influences the structural formation of their memory trace.This research was supported by a grant from the U.S. Office of Special Education and Rehabilitative Services. Special appreciation is given to Greelley District IV schools for providing subjects, to Missy Reda and Stephanie Contros for the data collection, and to two anonymous reviewers for their critical comments on a draft of this article.     

Adjustment to hemodialysis treatment through behavioral controls

The present study was conducted to examine the hypothesis that compliant chronically ill patients, typically described as adjusted, reinforce more positive social environments using behavioral controls than noncompliant patients, typically described as maladjusted. Specifically, it is hypothesized that diet-compliant chronic hemodialysis patients emit significnatly more active involvement-in-treatment behaviors and more social behaviors than diet-noncompliant chronic hemodialysis patients. Subjects, who ranged in age from 30 to 77 years, were outpatients at a kidney center. Behavioral observations were conducted to assess the occurrence or frequency of (1) four involvement-in-treatment behaviors that are routinely taught to all patients and (2) two social behaviors, which were patient verbalizations and smiles. The results showed that compliant patients emitted significantly more involvement-in-treatment behaviors and smiles than noncompliant patients. Results support the proposed control framework that compliant, in contrast to non-compliant, chronically ill patients have recourse through positive behavioral controls when adjusting to the stresses of illness. It was proposed that through these controls, compliant patients reinforce positive environments rather than simply respond to life circumstances as given.     

Do semantic memory deficiencies underlie learning disabled readers' encoding processes?

This study investigates the extent to which learning disabled readers' atypical encoding relates to their deficiencies in semantic memory. Inferences related to ability group performance were based on the assumption that encoding involves the matching of incoming information against a featural representation of that information in semantic memory. To this end, learning disabled and nondisabled readers in two age groups were compared on dichotic listening recall tasks that included orienting and nonorienting instructions. Orienting instructions directed children's attention toward semantic, phonemic, or structural word features. Dependent measures were lateralization, free recall, retrieval organization, and selective attention. The efficiency of allocating attentional resources was inferred from correlations between central and incidental recall. Primary results included the following: Disabled and nondisabled readers' ear asymmetry differences were dependent upon age, orienting instructions, and type of word list; disabled readers' recall and organization scores were lower than skilled readers'; however, both ability groups benefitted from orienting instructions compared to nonorienting instructions; during orienting instructions, disabled readers were less able than skilled readers to divide their attention between target and nontarget word features, especially during interhemispheric processing conditions; and the relative efficiency of allocating attentional resources differed qualitatively between the two ability groups. The results suggest that ability group variations reflect the structure of the memory trace in interaction with ear presentation and encoding processes. It is inferred that disabled readers' inferior memory traces reflect the quantity and internal coherence of information stored in semantic memory as well as the means by which such information is accessed.     

Semantic and visual memory codes in learning disabled readers

Two experiments investigated whether learning disabled readers' impaired recall is due to multiple coding deficiencies. In Experiment 1, learning disabled and skilled readers viewed nonsense pictures without names or with either relevant or irrelevant names with respect to the distinctive characteristics of the picture. Both types of names improved recall of nondisabled readers, while learning disabled readers exhibited better recall for unnamed pictures. No significant difference in recall was found between name training (relevant, irrelevant) conditions within reading groups. In Experiment 2, both reading groups participated in recall training for complex visual forms labeled with unrelated words, hierarchically related words, or without labels. A subsequent reproduction transfer task showed a facilitation in performance in skilled readers due to labeling, with learning disabled readers exhibiting better reproduction for unnamed pictures. Measures of output organization (clustering) indicated that recall is related to the development of superordinate categories. The results suggest that learning disabled children's reading difficulties are due to an inability to activate a semantic representation that interconnects visual and verbal codes.     

Preprocessing on the basis of frequency of occurrence

The release from PI methodology was used to test Oldfield's (1966) suggestion that human memory is organized in part on the basis of frequency of occurrence. An observed release from PI identified frequency of occurrence as an encoding category and provided support for the underlying assumptions of Oldfield's model.     

Retrieval time as a function of memory ensemble size

A direct test was performed of Oldfield's (1966) derivation of the relationship between naming response latency and memory ensemble size. The results confirmed Oldfield in every particular. Further, the results support Sperling's (1967) suggestion of a recognition buffer-memory mechanism between the initial stimulus-encoding stage and the long-term memory stage of human information processing.     

Willingness to Seek Help as a Function of Self-Disclosure and Problem Severity

In this study the authors examined the effects of problem severity, amount of self-disclosure, and self-disclosure flexibility on willingness to seek help for a problem. The participants were 101 midwestern university students enrolled in an introductory psychology course who had not had previous counseling experience. The participants completed the Jourard Self-Disclosure Questionnaire (SDQ), the Chelune Self-Disclosure Situations Survey (SDSS), and responded to questions after reading a scenario depicting a personal problem of either high or low severity. The results indicated that the factors that predicted the greatest amount of variance in willingness to seek help were the interaction of problem severity with willingness to self-disclose to a counselor, followed by problem severity; no gender differences were found. Implications for counseling and further research are discussed.     

Opportunities For Learning: Course Sequences and Positional Advantages

Course sequences are strands of courses in particular content areas that span a student's educational career. Courses that are differentiated and sequentially organized, such as mathematics and science course sequences, create opportunities for positional advantages in a school's curricular structure. When students make a nonroutine change of schools – that is, transferring to a school outside of the regular attendance zone – they are at risk of changing their positional advantage. Using data from the National Education Longitudinal Study of 1988–94 (NELS:88–94), we examine the educational outcomes of sequences and explore curricular dislocations within the context of school choice. We find that the strongest predictors of 12th-grade mathematics and science course sequences are a student's course sequences at 10th grade. With regard to outcomes, students in higher mathematics and science sequences show greater achievement gains. Furthermore, students in higher mathematics sequences are less likely to have behavior problems and are more likely to graduate from high school and attend college. Students who make a nonroutine change of schools are more likely to be in lower course sequences than students who do not transfer. Thus, course sequences in mathematics and science are tangible experiences with real consequences for students' lives during and beyond high school and are sensitive to transitions which disrupt the continuity of students' high school careers.     

Individual and age-related differences in children’s working memory

The purpose of this study was to investigate the degree to which age-related and individual differences in children’s working memory (WM) are due to a general or task-specific capacity system. Experiment 1 correlated children’s (N=146; age range 5–19 years) verbal and visual-spatial working memory performance with various intelligence and achievement measures. The results supporting a general system were that (1) visual-spatial and verbal WM measures were significantly intercorrelated with and without age partialed out and (2) both verbal and visual-spatial WM measures were significantly correlated with diverse achievement and intelligence measures. Experiment 2 compared three age groups (N=192; 7-, 10-, and 13-year-olds) on working-memory performance tasks under initial, enhanced (cued), and maintenance conditions. The results supporting a general capacity system were that (1) age-related performance differences in WM were found on all conditions and not isolated to specific processes, (2) the maintenance measures (high-load condition) predicted the variance better in age-related performance than process measures, and (3) although individual differences in WM performance reflected two independent operations, these operations produced similar correlations to achievement within age groups. Overall, the results support a general capacity explanation of age-related and individual differences in children’s WM performance.