Leslie J. Caplan

Category representations and their implications for category structure

In a series of experiments and reanalyses of previous research, we tested the hypothesis that categories that are primarily represented by extrinsic features (i.e., those that are relations between two or more entities) would yield more graded structures than would categories primarily represented by intrinsic features (i.e., those features true of an item considered in isolation). These predictions were confirmed. Extrinsically represented categories showed (1) less agreement across subjects on membership judgments, (2) more graded membership in a membership judgment task, and (3) smaller differences between gradients of typicality and of membership judgments

The Structure of Postconcussive Symptoms in 3 Us Military Samples

Objective:To evaluate alternative models of symptom clusters for the 22-item Neurobehavioral Symptom Inventory. Participants:Three military samples, including 2 nonclinical samples (n = 2420, n = 4244) and 1 sample of individuals with recent head injury (n = 617). Methods:In the first sample, exploratory factor analysis of Neurobehavioral Symptom Inventory responses was performed with tests of significant factors and model fit. In the other 2 samples, confirmatory factor analysis evaluated the fit of 3 models: 2- and 3-factor models based on the initial exploratory factor analysis, and a 9-factor model based on prior research. Main Outcome Measures:The exploratory factor analysis used 2 tests for the number of factors: Parallel Analysis and Minimum Average Partial test. Confirmatory factor analysis models were evaluated using 2 measures of model fit, Root Mean Square Error of Approximation and Comparative Fit Index. Results:Postconcussive symptoms can be described accurately by the 9 factors. However, the model of 3 intercorrelated factors, reflecting cognitive, affective, and somatic/sensory symptoms, fits the data more parsimoniously with little loss in model fit. Conclusion:Although the 9-cluster result from prior research provides a valid description of the relations among items of the inventory, a 3-factor model, consisting of somatic/sensory, affective, and cognitive factors, provides nearly as good a fit to the data, with greater parsimony. We encourage clinicians and researchers to conceptualize the Neurobehavioral Symptom Inventory in terms of 3 coherent clusters of symptoms rather than as 22 individual items.

A Time Course Analysis of Stroop Interference and Facilitation: Comparing Normal Individuals and Individuals With Schizophrenia

Using randomized stimulus onset asynchrony (SOAs), the authors traced the time course of Stroop interference and facilitation in normal participants and participants with schizophrenia. Unlike earlier findings using blocked SOAs, singular peaks in interference, facilitation, or both occurred at particular SOAs. The peaks of normal participants and participants with schizophrenia differed. Findings are congruent with a model of Stroop performance that posits individual differences in processing speeds of target and nontarget stimulus dimensions, coupled with critical points in response selection. Participants with schizophrenia also showed more overall interference than normal control participants. A second experiment that added a temporal gap between the distractor word and target color obliterated Stroop effects only for individuals with schizophrenia. These findings provide a new empirical basis for models of Stroop effects. They are also consistent with hypotheses about the importance of the prefrontal cortex for working memory and prefrontal dysfunction in schizophrenia.

Adult age differences in memory for routes : effects of instruction and spatial diagram

Free-recall and multiple-choice measures of memory for landmarks, sequential order, turns, and route configurations were obtained from younger and older adults after they viewed slides of 2 overlapping routes. Instructions focused attention on either the contents of the slides or on the course of the path; a control condition provided no orientational instructions. Half the subjects viewed maplike diagrams of the joint spatial configuration. Age interacted with instruction only for multiple-choice tests of landmark memory. Age interacted with diagram for each of the other 3 route memory components, although the generality of this interaction across instruction condition depended on whether free-recall or multiple-choice tests were used. The results suggest that route memory may involve both scene and layout representation, which may be differentially sensitive to age and presentational variables.

Socioeconomic status and financial coping strategies : The mediating role of perceived control

We examine the relations among socioeconomic status, control beliefs, and two coping styles (problem-focused vs. emotion-focused) in the context of financial stress. Findings indicate that low socioeconomic status (SES) is linked to greater use of emotion-focused financial coping and lesser use of problem-focused financial coping. The effects of SES on the use of problem-focused financial coping appear to be entirely mediated by two measures of perceived control: self-confidence and fatalism. In contrast, the effects of SES on emotion-focused financial coping are not mediated in this way. Results also indicated that problem-focused and emotion-focused financial coping are differentially related to financial stress and to general psychosocial distress. These results suggest that low SES may decrease ones control beliefs, which in turn decrease the likelihood of choosing effective financial coping processes, resulting in double disadvantage.

Continued inhibitory capacity throughout adulthood : Conceptual negative priming in younger and older adults

Two negative priming experiments in older and younger adults are reported. Participants in Experiment 1, involving both positive and negative priming conditions, showed both types of priming. There were no significant differences between age groups. If anything, older participants showed more negative priming. In Experiment 2, involving only negative priming conditions, similar results were obtained. Our findings rule out possible effects of experimental conditions that episodic retrieval theorists have suggested might account for negative priming in older adults. Although our results may be consistent with an explanation of negative priming in older adults by an expansively specified theory of episodic retrieval, they are at least as consistent with the view that inhibitory processes are intact in older adults. In light of these findings, conflicting empirical results and alternative views of negative priming in older adults are examined.

The effects of analogical training models and age on problem-solving in a new domain

Young and middle-aged adults learned a microcomputer drawing package either with or without an analogical model of the package. Following training, problem-solving flexibility was assessed. Although no age differences were obtained following no-model training, middle-aged subjects performed worse than young subjects following model-based training. These results support the hypothesis that model-based training encourages elaboration and abstraction processes, and that older adults are less likely or less able to engage in such processing.

Problem solving by reference to rules or previous episodes: the effects of organized training, analogical models, and subsequent complexity of experience.

Subjects learned a microcomputer drawing package under different conditions of training organization and practice complexity. Training instructions were presented in either a random or an organized order, and with or without an analogical model of the software package. Practice trials varied in visual and logical complexity. Performance on paper-arid-pencil and problem-solving tests was better following the model than following the no-model condition when practice trials were logically complex; the reverse was true when they were logically simple. Performance on the test of problem solving was also better following organized training than following randomly ordered training when practice trials were visually complex; the reverse was true following visually simple practice. We propose that the subjects performed the tasks by engaging in either episodebased or rule-based processing, and that performance was optimized when the processing used at encoding and retrieval was the same. The acquisition of skill in solving real problems is explained as procedural compilation.

The Latent Structure of Memory: A Confirmatory Factor-Analytic Study of Memory Distinctions

Confirmatory factor analysis was used to investigate the nature of memory distinctions underlying the performance of two samples: a sample of male Vietnam War veterans who had not received head injuries, and a second sample of male Vietnam War veterans who had suffered penetrating head injuries resulting in relatively small lesions (<10 cc volume loss). For these two groups, comparisons were made of the fit of seven theory-based memory models, comprising from one to four factors. The four-component model with a verbal-episodic component, a visual-episodic component, a semantic component, and a short-term memory component provided a significantly better account of memory performance than the others. The implications of these findings and some advantages of this approach as a supplement to a purely experimental approach to memory are discussed.

Brain lesion and memory functioning: short-term memory deficit is independent of lesion location.

We analyzed the effects of patterns of brain lesions from penetrating head injuries on memory performance in participants of the Vietnam Head Injury Study (Grafman et al., 1988). Classes of lesion patterns were determined by mixture modeling (L. K. Muthén & B. O. Muthén, 1998–2004). Memory performance was assessed for short-term memory (STM), semantic memory, verbal episodic memory, and visual episodic memory. The striking finding was that large STM deficits were observed in all classes of brain-injured individuals, regardless of lesion location pattern. These effects persist despite frequent concomitant effects of depressive symptomatology and substance dependence. Smaller deficits in semantic memory, verbal episodic memory, and visual episodic memory depended on lesion location, in a manner roughly consistent with the existing neuropsychological literature. The theoretical and clinical implications of the striking, seemingly permanent STM deficits in individuals with penetrating head injuries are discussed.