On adaptation, maximization, and reinforcement learning among cognitive strategies

Analysis of binary choice behavior in iterated tasks with immediate feedback reveals robust deviations from maximization that can be described as indications of 3 effects: (a) a payoff variability effect, in which high payoff variability seems to move choice behavior toward random choice; (b) underweighting of rare events, in which alternatives that yield the best payoffs most of the time are attractive even when they are associated with a lower expected return; and (c) loss aversion, in which alternatives that minimize the probability of losses can be more attractive than those that maximize expected payoffs. The results are closer to probability matching than to maximization. Best approximation is provided with a model of reinforcement learning among cognitive strategies (RELACS). This model captures the 3 deviations, the learning curves, and the effect of information on uncertainty avoidance. It outperforms other models in fitting the data and in predicting behavior in other experiments.     

AMPA/kainate, NMDA, and dopamine D1 receptor function in the nucleus accumbens core: a context-limited role in the encoding and consolidation of instrumental memory

Neural integration of glutamate- and dopamine-coded signals within the nucleus accumbens (NAc) is a fundamental process governing cellular plasticity underlying reward-related learning. Intra-NAc core blockade of NMDA or D1 receptors in rats impairs instrumental learning (lever-pressing for sugar pellets), but it is not known during which phase of learning (acquisition or consolidation) these receptors are recruited, nor is it known what role AMPA/kainate receptors have in these processes. Here we show that pre-trial intra-NAc core administration of the NMDA, AMPA/KA, and D1 receptor antagonists AP-5 (1 microg/0.5 microL), LY293558 (0.01 or 0.1 microg/0.5 microL), and SCH23390 (1 microg/0.5 microL), respectively, impaired acquisition of a lever-pressing response, whereas post-trial administration left memory consolidation unaffected. An analysis of the microstructure of behavior while rats were under the influence of these drugs revealed that glutamatergic and dopaminergic signals contribute differentially to critical aspects of the initial, randomly emitted behaviors that enable reinforcement learning. Thus, glutamate and dopamine receptors are activated in a time-limited fashion-only being required while the animals are actively engaged in the learning context.     

Evidence for holistic representations of ignored images and analytic representations of attended images

According to the hybrid theory of object recognition (J. E. Hummel, 2001), ignored object images are represented holistically, and attended images are represented both holistically and analytically. This account correctly predicts patterns of visual priming as a function of translation, scale (B. J. Stankiewicz & J. E. Hummel, 2002), and left-right reflection (B. J. Stankiewicz, J. E. Hummel, & E. E. Cooper, 1998). The model also predicts that priming for attended images will generalize over configural distortions (split images), whereas priming for ignored images will not. Three experiments tested and confirmed this prediction. Split images visually primed their intact and split counterparts when they were attended but not when they were ignored, whereas intact images primed themselves whether they were attended or not. The data contribute to the growing body of evidence that 1 function of visual attention is to permit the generation of explicitly relational representations of object shape.     

Using talking computers to remediate reading and spelling disabilities: The critical role of the print-to-sound unit

Talking computers employing computer-generated speech feedback have been used to remediate the literacy skills of dyslexic readers. A computer program is described that employs DECtalk, a highlevel speech synthesizer, to narrate instruction involving intensive training in identifying whole words or in identifying and blending word segments corresponding to onsets, rimes, and phonemes. Procedures for developing individualized instruction are described as well as for constructing and editing the speech and graphics features of the program. Neurologically impaired dyslexic children trained with this program achieved greater acquisition and transfer of word recognition skill when their training involved segmented rather than whole word feedback.     

SMARTS and SMARTER: Improved Simple Methods for Multiattribute Utility Measurement

This paper presents two approximate methods for multiattribute utility measurement, SMARTS and SMARTER, each based on an elicitation procedure for weights. Both correct an error in SMART, originally proposed by Edwards in 1977, and in addition SMARTER is simpler to use. SMARTS uses linear approximations to single-dimension utility functions, an additive aggregation model, and swing weights. The paper proposes tests for the usability of these approximations. SMARTER, based on a formally justifiable weighting procedure developed by Barron and Barrett, uses the same procedures as SMARTS except that it omits the second of two elicitation steps in swing weights, substituting calculations based on ranks. It can be shown to perform about 98% as well as SMARTS does, without requiring any difficult judgments from elicitees.     

Local homogeneity in latent trait models. A characterization of the homogeneous monotone irt model

The stochastic subject formulation of latent trait models contends that, within a given subject, the event of obtaining a certain response pattern may be probabilistic. Ordinary latent trait models do not imply that these within-subject probabilities are identical to the conditional probabilities specified by the model. The latter condition is called local homogeneity. It is shown that local homgeneity is equivalent to subpopulation invariance of the model. In case of the monotone IRT model, local homogeneity implies absence of item bias, absence of item specific traits, and the possibility to join overlapping subtests. The following characterization theorem is proved: the homogeneous monotone IRT model holds for a finite or countable item pool if and only if the pool is experimentally independent and pairwise nonnegative association holds in every positive subpopulation.This research was supported by the Dutch Interuniversity Graduate School of Psychometrics and Sociometrics. The authors wish to thank two reviewers for their thorough comments.     

What's in a name: what analyst and patient call each other

Awkward moments often arise between patient and analyst involving the question, "What do we call each other?" The manner in which the dyad address each other contains material central to the patient's inner life. Names, like dreams, deserve a privileged status as providing a royal road into the paradoxical analytic relationship and the unconscious conflicts that feed it. Whether an analyst addresses the patient formally, informally, or not at all, awareness of the issues surrounding names is important.     

Development of animal recognition: a difference between Parts and Wholes

A series of experiments examined children's recognition of animals by their features (Parts) and by the relative scale of the parts (Wholes). They were asked to identify the correct picture of an animal they could name from the original plus two computer-generated alternatives. We examined the developmental trends associated with upright (Studies 1 and 3) and inverted presentations (Study 3). Both experiments confirmed children's superior ability in dealing with the recognition of animal Parts over animal Wholes, especially for the younger ages tested (6- and 10-year-olds). It was not until the ages of 15-16 that children demonstrated equal performance on Whole and Part items. The late acquisition of animal Whole recognition is compared to the late acquired configural skills proposed for face recognition.