Base-rate effects in category learning: a comparison of parallel network and memory storage-retrieval models

Exemplar-memory and adaptive network models were compared in application to category learning data, with special attention to base rate effects on learning and transfer performance. Subjects classified symptom charts of hypothetical patients into disease categories, with informative feedback on learning trials and with the feedback either given or withheld on test trials that followed each fourth of the learning series. The network model proved notably accurate and uniformly superior to the exemplar model in accounting for the detailed course of learning; both the parallel, interactive aspect of the network model and its particular learning algorithm contribute to this superiority. During learning, subjects' performance reflected both category base rates and feature (symptom) probabilities in a nearly optimal manner, a result predicted by both models, though more accurately by the network model. However, under some test conditions, the data showed substantial base-rate neglect, in agreement with Gluck and Bower (1988b).     

Memory storage and retrieval processes in category learning

The detailed course of learning is studied for categorization tasks defined by independent or contingent probability distributions over the features of category exemplars. College-age subjects viewed sequences of bar charts that simulated symptom patterns and responded to each chart with a recognition and a categorization judgment. Fuzzy, probabilistically defined categories were learned relatively rapidly when individual features were correlated with category assignment, more slowly when only patterns carried category information. Limits of performance were suboptimal, evidently because of capacity limitations on judgmental processes as well as limitations on memory. Categorization proved systematically related to feature and exemplar probabilities, under different circumstances, and to similarity among exemplars of categories. Unique retrieval cues for exemplar patterns facilitated recognition but entered into categorization only at retention intervals within the range of short-term memory. The findings are interpreted within the framework of a general array model that yields both exemplar-similarity and feature-frequency models as special cases and provides quantitative accounts of the course of learning in each of the categorization tasks studied.     

SIGNIFICANCE TESTING IN PSYCHOLOGICAL RESEARCH:

Abstract— Empirical surveys show that reports of significance tests appear in the vast majority of articles in psychological research journals and are relied on by both investigators and journal reviewers when making decisions about replication of experiments and submission and acceptance of research reports Evaluation of claims by critics that significance testing is, nonetheless, counterproductive yields suggestions for improvements of prevailing practices, but also the recommendation that decisions about significance testing versus alternative procedures should remain the province of the individual investigator, unconstrained by mandates or prohibitions by publishers or officials of scientific associations. The prime focus for efforts toward improvement of research design and data analysis in psychology and other behavioral sciences should be upgrading the mathematical and general scientific preparation of students preparing for research careers in these fields     

Serial position functions for letter identification at brief and extended exposure durations

The properties of serial position functions for tachistoscopic report were investigated over a wide range of viewing times. Four-letter strings of random consonants were presented in varying display locations relative to the fixation point with the observers’ eye movements monitored to limit them to a single fixation for each display. Salient properties of the serial position curves include an overall central-peripheral gradient, higher performance at the ends than the interior of letter strings regardless of absolute location, and left-right asymmetry in the visual field, all of these being largely independent of viewing time. Errors reflecting loss of positional information are prominent even at extended viewing times, are more nearly symmetrical in the left and right visual fields than other types of errors, and, in contrast to item errors, occur less frequently in letter sequences that have high frequencies in English. Further, transposition errors exhibit a pronounced peripheral-to-central drift, possibly reflecting gradients of positional uncertainty. Such gradients may be implicated in the peripheral-central asymmetry of the lateral interference effects exerted by other letters on a target letter in a nonfoveal location.     

The importance of being nonalignable: a critical test of the structural alignment theory of similarity

The structural alignment theory of similarity distinguishes 2 types of difference that may occur between stimuli: Alignable differences are those related to a commonality, whereas nonalignable differences are not related to a commonality. Alignment theory predicts that alignable differences should be more heavily weighted than nonalignable differences in similarity judgment. Experiments 1 and 2 demonstrate that, contrary to this prediction, nonalignable differences exerted a greater impact than alignable differences in similarity and difference judgments of geometric stimuli. Experiment 3 revealed that the relative weight accorded a given difference was also affected by contextual constraints. Thus, although the experiments supported the validity of the distinction between alignable and nonalignable differences, results were discordant with the specific prediction of structural alignment theory.     

Age-Related Differences in Lay Conceptions of Well-Being and Experienced Well-Being

Conceptions of well-being are defined as a system of beliefs concerning the nature and experience of well-being and can be described generally by the degree to which four dimensions, representing (1) the experience of pleasure, (2) avoidance of negative experience, (3) selfdevelopment, and (4) contribution to others, are emphasized. A first main objective of the current study was to investigate age-related differences in younger and older adults’ conceptions of well-being. A second main objective was to address whether conceptions of well-being are differentially associated with experienced well-being in younger and older adults. Results indicated several age-related differences in conceptions of well-being, with younger adults reporting more emphasis on the experience of pleasure and self-development, older adults reporting more emphasis on avoidance of negative experience, and younger and older adults reporting similar levels of emphasis on contribution to others. Results further indicated several age-related differences in associations between the experience of pleasure and avoidance of negative experience dimensions and well-being, with these two dimensions being more strongly and positively associated with well-being in older adults. Self-development and contribution to others were found to be positively associated with well-being regardless of age.     

The Gender Gap on Wall Street: An Empirical Analysis of Confidence in Investment Decision Making

We attempted to identify the personal characteristics that influence confidence in an investment decision in an experiment administered to 1,359 subjects nationwide. Multiple regression was used to control statistically for variation among subjects and to develop a model of investment decision confidence. The most striking finding was that women had significantly lower confidence in an investment task than men, after controlling for all other relevant variables and characteristics including the amount of the investment decision itself. Familiarity with and present attitude about investing in the stock market, college credit hours in accounting and finance, experience in evaluating common stocks, the current level of the stock market, and the investment decision itself (the amount to be invested) were also found to be significant. Age, value of personal portfolio, years of college, and years of business experience were not significant characteristics.     

Convergent and divergent thinking in verbal analogy

Individual differences in convergent and divergent thinking may uniquely explain variation in analogical reasoning ability. Across two studies we investigated the relative influences of divergent and convergent thinking as predictors of verbal analogy performance. Performance on both convergent thinking (i.e., Remote Associates Test) and divergent thinking (i.e., Alternative Uses Task) uniquely predicted performance on both analogy selection (Studies 1 and 2) and analogical generation tasks (Study 2). Moreover, convergent and divergent thinking were predictive above and beyond creative behaviours in Study 1 and a composite measure of crystallised intelligence in Study 2. Verbal analogies in Study 2 also varied in semantic distance, with results demonstrating divergent thinking as a stronger predictor of analogy generation for semantically far than for semantically near analogies. Results thus further illuminate the link between analogical reasoning and creative cognition by demonstrating convergent and divergent thinking as predictors of verbal analogy.