Biological implementation of the temporal difference algorithm for reinforcement learning: Theoretical comment on O'Reilly et al. (2007).

The ability to survive in the world depends critically on the brain's capacity to detect earlier and earlier predictors of reward or punishment. The dominant theoretical perspective for understanding this capacity has been the temporal difference (TD) algorithm for reinforcement learning. In this issue of Behavioral Neuroscience, R. C. O'Reilly, M. J. Frank, T. E. Hazy, and B. Watz (2007, see record 2007-02025-004)) propose a new model dubbed primary value and learned value (PVLV) that is simpler than TD, and they claimed that it is biologically more realistic. In this commentary, the author suggests some slight modifications of a previous biological implementation of TD instead of adopting the new PVLV algorithm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The nature and processes of preverbal learning: implications from nine-month-old infants' discrimination problem solving

Nine-month-old infants' performance on discrimination-learning problems was investigated in four experiments using the synchronous reinforcement paradigm. These experiments were organized around basic theoretical postulates concerning the relation between attention and learning. In each of the experiments, infants were trained to respond differentially to a particular stimulus feature, with the goal of establishing whether they could learn to respond to a particular stimulus feature under conditions where other stimulus dimensions were present and varying. In the first experiment, 48 infants were trained to fixate visually on a particular feature in a pair of stimuli that varied in color, form, and position dimensions. Contingencies for responding were then shifted either within a dimension (reversal shift) or across dimensions (nonreversal shift). Infants learned to respond to the reinforced feature during initial training; moreover, infants assigned to a reversal shift condition showed a higher level of transfer of learning during the test phase than those assigned to a nonreversal shift condition. The second experiment extended the results of Experiment 1 by testing 48 additional infants under conditions in which the number of varying irrelevant dimensions was increased during the shift phase. Although the difficulty added to this task by this manipulation made transfer more difficult for all infants, results again indicated that transfer of learning was more evident for infants in a reversal shift than a nonreversal shift condition. In the third experiment, 64 infants were trained in a similar manner, except that completely new values were substituted during shift phases on the color and form dimensions. This manipulation was meant to probe whether infants were formulating a dimension response from previous training and to test the predictions of such dimension processing for transfer of learning to a functionally new problem. Infants were reinforced for fixating on a new feature either within the same dimension as during training (intradimension shift) or within the dimension that was not originally trained (extradimension shift). Transfer of learning was clearly superior in the intradimension shift condition. The findings of the first three experiments suggested that, during discrimination-learning problems, infants selected and tested individual stimulus features and dimensions from an array of potential solutions to the problem until discovering the one that was consistently associated with reinforcement.(ABSTRACT TRUNCATED AT 400 WORDS)     

The subgoal learning model: Creating better examples so that students can solve novel problems.

Learners have great difficulty solving problems requiring changes to solutions demonstrated in examples. However, if the solution procedures learners form are organized by subgoals, then they are more successful. Subgoal learning is hypothesized to be aided by cues in example solutions that indicate that certain steps go together. These cues may induce a learner to attempt to self-explain the purpose of the steps, resulting in the formation of a subgoal. Across 4 experiments it was found that a label for a group of steps in examples helped participants form subgoals as assessed by measures such as problem-solving performance and talk aloud protocols. Abstract labels were more likely than superficial labels to lead participants to form subgoals with fewer ties to surface features. Subgoals guide problem solving by helping learners focus on the steps to modify in novel problems that involve the same subgoals but require new steps to achieve them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cumulative damage and the response of human bone in two-step loading fatigue

It has already been shown that in fatigue tests in vitro human cortical bone accumulates damage in the form of microcracks and that the total number of microcracks generated prior to the creation of the fatal macrocrack, and their effect (softening) on the material properties, depends on the level of applied stress. At each stress level the amount of accumulated damage has also been shown to be a non-linear function of the cycle number (Zioupos et al., 1996a, b; Pattin et al., 1996). The theoretical implications of the previous findings and two possible models for cumulative damage were put to the test here by performing tensile fatigue tests in two-step level (high/low or low/high) loading on human cortical bone specimens. The results indicate that the accumulation of damage in-vitro is highly dependent on the level of stress and the stress history. Usual linear expressions for fatigue lifetime predictions, like the Palmgren-Miner rule, substantially over or underestimate the outcome depending on whether the stress was applied in a high/low or a low/high sequence, respectively. In view of these discrepancies we conclude that predicting the fatigue lifetime of any bone in vivo under variable loading and complex history regimes is an extremely difficult task to which the study of accumulation of damage can offer a significant but, perhaps, still limited contribution.     

Integrated Storm-Water Management for Watershed Sustainability

One aspect of integrated watershed management evaluates the impact of development on the local hydrologic cycle and, in particular, drinking water, wastewater, and storm-water infrastructure. Sustainable storm-water management focuses on selecting storm-water controls based on an understanding of the problems in local receiving waters that result from runoff discharges. For example, long-term problems associated with accumulations of pollutants in water bodies include sedimentation in conveyance systems and receiving waters, nuisance algal growths, inedible fish, undrinkable water, and shifts to less sensitive aquatic organisms. Short-term problems associated with high pollutant concentrations or frequent high flows (event-related) include swimming beach closures, water quality violations, property damage from increased flooding, and habitat destruction. A wide variety of individual storm-water controls usually must be combined to form a comprehensive wet weather management strategy. Unfortunately, combinations of controls are difficult to analyze. This will require new modeling techniques that can effectively evaluate a wide variety of control practices and land uses, while at the same time ensure that the flood-control objectives also are met. The results of these new models and novel techniques used for storm-water control then can be incorporated into an evaluation of the urban water cycle for a specific service area to determine whether storm-water controls can provide additional benefits such as reduction of potable water use and reduction of sanitary sewer overflow events.     

A model of dual attitudes.

When an attitude changes from A? to A?, what happens to A?? Most theories assume, at least implicitly, that the new attitude replaces the former one. The authors argue that a new attitude can override, but not replace, the old one, resulting in dual attitudes. Dual attitudes are defined as different evaluations of the same attitude object: an automatic, implicit attitude and an explicit attitude. The attitude that people endorse depends on whether they have the cognitive capacity to retrieve the explicit attitude and whether this overrides their implicit attitude. A number of literatures consistent with these hypotheses are reviewed, and the implications of the dual-attitude model for attitude theory and measurement are discussed. For example, by including only explicit measures, previous studies may have exaggerated the ease with which people change their attitudes. Even if an explicit attitude changes, an implicit attitude can remain the same. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning-forgetting rate independence defined by forgetting function parameters or forgetting function form: Reply to Loftus and Bamber and to Wixted.

This article is a reply to the comments of G. R. Loftus and D. Bamber (see record 1991-06492-001) and J. T. Wixted (see record 1991-06505-001) on a recent article of mine (R. S. Bogartz, see record 1990-09037-001). Various errors and misunderstandings of my approach in those comments are corrected and clarified. It is argued that the question of whether or not forgetting rate depends on the amount of initial learning is best answered by first providing a theoretical definition of forgetting, specifying a forgetting function, defining a rate of forgetting in terms of that function, and then determining whether the initial level of learning appears as a parameter influencing the value of the rate of forgetting. This view opposes that of Loftus and Bamber, who define the learning–forgetting rate issue in terms of the form of the forgetting function itself, and maintain that forgetting rate is independent of rate of learning only if the retention function is a monotone transformation of an exponential function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vision in repetitive circle drawing

Although most strategies of vaccination require immunopotentiation to induce efficient immune responses, the development of new adjuvants for human vaccines is highly limited by safety problems. In order to overcome this problem, we developed a new vaccine formulation based on the covalent linkage of protein or peptide to synthetic microspheres. In previous experiments performed in mice, we demonstrated that these particulate antigens induce strong antigen-specific CD4+ T cell proliferative responses in the absence of adjuvant. In the present study, we analyzed the immunogenicity in primate Saimiri sciureus monkeys of two different proteins linked to synthetic microspheres. Immune responses induced by these particulate proteins administered without adjuvant were compared to those stimulated by the soluble antigens injected with alum. We currently demonstrated that, in monkeys, particulate antigens administered without adjuvant, induced good PBMC proliferative response and antibody production. Furthermore, the analysis of antibody responses using mAbs specific for different Saimiri sciureus immunoglobulins showed that the antibody response profiles were different in monkeys immunized with soluble versus particulate form of antigens. Results of this study demonstrate that particulate form of antigen may stimulate qualitatively different immune responses as compared to alum and therefore suggest that this new antigen formulation could be an attractive candidate for the development of vaccines.     

Modality specificity of implicit memory for new associations.

In previous research we demonstrated that newly acquired associations between unrelated word pairs influence the magnitude of priming effects on word-completion tests. This phenomenon of implicit memory for new associations is observed only following semantic study elaboration. The present experiments reveal that implicit memory for new associations, though elaboration dependent, is also modality specific: Associative effects on a visual word-completion test were consistently reduced by study-test modality shifts. In contrast, explicit memory for new associations, as indexed by cued-recall performance, was uninfluenced by modality shifts. The modality effect on completion performance was eliminated when subjects were given brief visual preexposures to, or were required to construct visual images of, word pairs presented in auditory study conditions. The results pose a theoretical puzzle insofar as they indicate that within the domain of implicit memory, access to the products of elaborative processing depends on modality-specific, sensory-perceptual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Post and core reconstruction for fixed prosthodontic restoration

If the previous restorative therapy or dental caries has resulted in substantial loss of tooth structure, the abutment teeth for fixed prosthodontic restorations require a core reconstruction or a post and core. Small dentin defects can be restored with bonded cores; more extensive dentin defects that are often accompanied by previous endodontic treatment generally require additional support for the core material. A direct procedure with a bonded post is a viable treatment method. The decision to use either light-conducting all-ceramic zirconium or titanium as a post material depends on the aesthetic requirements present. The indications for a cast post and core as an indirect procedure for prosthodontic reconstructions appear to be decreasing. The learning objective of this article is to review the past and current post and core materials and techniques. Indications for core reconstruction with vital teeth and posts and cores for pulpless teeth are discussed.     

On the social psychology of the stock market: Aggregate attributional effects and the regressiveness of prediction.

The expectation that changes will either persist or regress to previous levels depends in large part on whether causal attributions are provided to explain recent changes. If these attributions are provided, then the tendency to make regressive predictions is diminished. It is argued that the news media provide such attributions and so cause aggregate-level changes in the predictions of those who receive these communications and thereby in receivers' subsequent behaviors. Causal attributions by members of the media should be expected to be more frequent and more extreme than those that would be generated by individuals who do not expect to communicate information to others. This aggregate attributional process, whereby one group acts on the attributions provided by another, is illustrated in financial markets. First, this research shows that the financial press explains recent changes in stock prices with good news after price rises and with bad news after price falls. In an experimental study, such news is shown to lead to less regressive predictions. The normative and theoretical implications of the results for economic and psychological processes are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variable Material Length Scale Associated with Nanoindentation Experiments

Material length scale that can be used in nonlocal gradient theories is obtained in this work based on experimental observations for two metals using nanoindentation experiments. The materials are cold rolled 1018 steel and oxygen free high conductivity copper. A fixed value of the material length scale is not always realistic and different problems under various conditions could require different values. Therefore, two models are proposed for a dynamic length scale that depends on strain rates and temperature. First the model is physically based, with parameters related to dislocation densities. This model introduces strain rate and temperature dependency in a coupled form. The second model is a phenomenological one that is based on hardness tests. Both models show that length scale decreases with increasing equivalent strain rate. The temperature effects are not studied in this work.     

The developmental relations between conceptual and procedural knowledge: A multimethod approach.

Interactions between conceptual and procedural knowledge influence the development of mathematical competencies. However, after decades of research, these interrelations are still under debate, and empirical results are inconclusive. The authors point out a source of these problems. Different kinds of knowledge and competencies only show up intertwined in behavior, making it hard to measure them validly and independently of each other. A multimethod approach was used to investigate the extent of these problems. A total of 289 fifth and sixth graders’ conceptual and procedural knowledge about decimal fractions was measured by 4 common hypothetical measures of each kind of knowledge. Study 1 tested whether treatments affected the 2 groups of measures in consistent ways. Study 2 assessed, across 3 measurement points, whether conceptual and procedural knowledge could be modeled as latent factors underlying the measures. The results reveal substantial problems with the validities of the measures, which might have been present but gone undetected in previous studies. A solution to these problems is essential for theoretical and practical progress in the field. The potential of the multimethod approach for this enterprise is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Methods of theoretical psychology.

Reviews the book, Methods of theoretical psychology by André Kukla (see record 2001-18914-000). This comprehensive survey of the tools of theoretical psychology is the culmination of the author's previous writings (e.g., Kukla 1989, 1995) wherein he tried to "convince psychologists that our discipline had suffered from a gross and systematic underestimation of the scope, variety, and import of theoretical work" and "persuade my colleagues that there are many important theoretical issues the resolution of which does not call for empirical research" (p. xi). This is not a book in theoretical psychology (the author cites as examples the volumes by Marx and Hillix, and Wolman), but a book about theoretical psychology, the "types of theoretical activities" that "require nothing but thinking" (p. xi). Notable is the book's epigraph, a quotation from Jerry Fodor claiming that the distinction between psychological and philosophical theorizing is merely heuristic, and issuing the moral challenge for a plurality of argument styles that transcends disciplines. For Kukla has written a book about the logic of science, or what was traditionally referred to as the philosophy of science, and, as might be expected, examples are strewn throughout from the natural sciences as well as some classic theoretical problems in psychology, most notably, cognitive science. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Validity" of short-form intelligence tests.

A short-form intelligence test is commonly "validated" by demonstrating a high correlation between it and the full scale from which it is taken. It has been argued, however, that the correlation between the short form and the full scale is less meaningful than the extent to which they agree in classifying individuals as to intellectual level; the latter depends in part upon the width of the categories in the classification system. A table is provided which shows the theoretical agreement between the short form and the full scale as a function of their correlation and category width. Empirical values from two studies approximate fairly closely the values given in this table. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Herpes management and prophylaxis

In summary, clinical management of HSV infection depends on an individual having an appropriate diagnosis and receiving proper counseling, follow-up of both themselves and their sexual partners, as well as having an opportunity to discuss with more knowledgeable physicians, the options for antiviral management should their individual problems and sequelae of genital HSV infection require it. Although some of the aspects of management such as HSV type 2 serology testing or continuous antiviral therapy will be limited in their availability to individuals worldwide because of cost, it is possible to improve knowledge among physicians about diagnosis. Furthermore, it is necessary to ensure that facilities for patient information and counselling are available. These latter facilities are often provided extremely efficiently by self-help or voluntary groups so it is vital that physicians understand and ensure that they obtain details of such groups to pass on to their patients.     

Interference between cognitive skills.

This study used a novel task, clock arithmetic, and a classic A–B/A–Br transfer design to investigate the presence of interference between cognitive skills. The A–B/A–Br design required participants to first learn problem-to-answer associations during training and then to learn new pairings between the same problems and answers during transfer. The associations learned during training interfered with those learned during transfer, as measured by slowed reaction times to emit the correct response, failures to retrieve any response, and intrusion errors. Interference persisted even after a 1-week retention interval and was especially prevalent during the warm-up period at the beginning of the retention test. The use of the A–B/A–Br design indicates that whether an incorrect answer retrieved from memory is emitted as a response depends on whether the intrusion is recognized as inappropriate for the current task. The long-term memory for cognitive skills means that attempts to learn new responses to old stimuli will be plagued by persistent intrusion errors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cumulative radiation effect. Part VI: simple nomographic and tabular methods for the solution of practical problems

In five previous papers, the concept of the Cumulative Radiation Effect (CRE) has been presented as a scale of accumulative sub-tolerance radiation damage. The biological effect generated in normal connective tissue by fractionated or continuous radiation therapy given in any temporal arrangement is described by the CRE on a unified scale of assessment, so that a unique value of the CRE describes a specific level of radiation effect. The basic methods of evaluating CREs were shown in these papers to facilitate a full understanding of the fundamental aspects of the CRE-system, but these methods can be time-consuming and tediuous for complex situations. In this paper, simple nomographic and tabular methods for the solution of practical problems are presented. An essential feature of solving a CRE problem is firstly to present it in a concise and readily appreciated form, and, to do this, nomenclature is introduced to describe schedules and regimes as compactly as possible. Simple algebraic equations are derived to describe the CRE achieved by multi-schedule regimes. In these equations, the equivalence conditions existing at the junctions between schedules are not explicit and the equations are based on the CREs of the constituent schedules assessed individually without reference to their context in the regime as a whole. This independent evaluations of CREs for each schedule results in a considerable simplification in the calculation of complex problems. The calculations are further simplified by the use of suitable tables and nomograms, so that the mathematics involved is reduced to simple arithmetical operations which require at the most the use of a slide rule but can be done by hand. The order of procedure in the presentation and calculation of CRE problems can be summarised in an evaluation procedure sheet. The resulting simple methods for solving practical problems of any complexity on the CRE-system are demonstrated by a number of examples.     

When can information from ordinal scale variables be integrated?

Many theoretical constructs of interest to psychologists are multidimensional and derive from the integration of several input variables. We show that input variables that are measured on ordinal scales cannot be combined to produce a stable weakly ordered output variable that allows trading off the input variables. Instead a partial order is obtained in which the amount of ordering depends on the number and nature of the input variables and the relationship between them. However, if trade-offs are excluded, it is still possible to obtain a weak order using lexicographic ordering of the input variables. An implication is that psychological processes that integrate information from different input variables and that produce consistent output require that the input variables be measured on more than ordinal scales. A further implication is that the level of measurement of the input variables affects the kind of psychological model that can be applied to the process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Covert focussing of the attentional gaze.

Developed and tested a binary mixture model to describe the level of detail of a visual form that is processed most quickly and is influenced both by volitional emphasis and by the level that most recently contained relevant information. The interaction of these 2 factors in controlling covert attentional focus is described in a model in which level emphasis depends on the entries in a Markov-like transition matrix. In a test with 5 undergraduates, the model outlined the major features of attention operating characteristic curves produced in a target discrimination paradigm requiring 2 successive judgments per trial; but it could not handle all of the details of individual Ss' data. In general, volition and previous processing had separate effects on covert attentional focus, but some Ss achieved quicker responding at an emphasized level of detail by relaxing on the nonemphasized level. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)