Surface dyslexia: A case report and some theoretical implications to reading models

This paper reports on the psycholinguistic investigation of a surface dyslexic aphasic patient's abilities to handle written material. The analysis of paralexic errors produced in reading aloud single words and nonwords classically suggested that the patient was using an analytical strategy parsing the letter string stimulus, from left to right, into graphemes, and assigning phonemic values to graphemes. The patient's results were found to be sensitive to irregularities in correspondence between graphemes and phonemes not only in reading aloud but in lexical decisions, writing on dictation, rhyming, and written-word comprehension. Moreover, the patient's linguistic behavior brought out the reverse pattern observed in deep-dyslexic performances within word/nonword and content/function word dimensions. It was found that some semantic information about written words could be retrieved from both phonological and nonphonological processes presumably operating concurrently and both providing converging or conflicting pieces of meaning to the understanding of written words. Some considerations derived from the observation of this pathological reading behavior are discussed, contributing to a psycholinguistic model of normal reading.     

Fixed and optional stopping models for two-choice discrimination times

Several current models for choice- or discrimination-time experiments represent the stimulus as a sequence of independent and identically distributed observations. This paper develops and compares models based on two different stopping rules that a subject might use to terminate his sampling process and convert his perceptual evidence into an observable response. The fixed and optional stopping rules yield different predicted forms for the speed/accuracy tradeoff function and for the relation between mean and variance of response times. These predictions are developed in the general case and then specialized for certain conditions of symmetry, so that the expressions are easier to apply and to compare between models. A later section considers how changes in stopping criteria (either between or within experimental trials) affect predictions about mean response times for correct responses and errors, and then uses these ideas to relate the optional stopping rule for the Random Walk models to those of the Accumulator models. A final section considers specialized models for stimulus detection and intensity discrimination that assume Poisson-distributed sensory input, and relates these models to the present fixed stopping model.     

Counting models of temporal discrimination

A three-category task was employed to test counting models for temporal discrimination. Unlike former approaches, the present one is not based on Weber functions. Specifically, the proposed test does not require the implicit but, nevertheless, debatable assumption that the pulse rate of the internal clock is constant for different durations of the standard interval. Furthermore, the present approach does not necessitate specific distributional assumptions about the interpulse times. An experiment was conducted to evaluate the predictions of this generalized counting model. The results are consistent with predictions of the generalized counting model. A further analysis suggests that the pulse rate decreases as the duration of the standard interval increases.     

Mathematical formulation of multivariate euclidean models for discrimination methods

Multivariate models for the triangular and duo-trio methods are described in this paper. In both cases, the mathematical formulation of Euclidean models for these methods is derived and evaluated for the bivariate case using numerical quadrature. Theoretical results are compared with those obtained using Monte Carlo simulation which is validated by comparison with previously published theoretical results for univariate models of these methods. This work is discussed in light of its importance to the development of a new theory for multidimensional scaling in which the traditional assumption can be eliminated that proximity measures and perceptual distances are monotonically related.     

Transfer of discrimination from solid objects to pictures by pigeons: A test of theoretical models of pictorial perception

Various authors have suggested that learning associations between objects and pictures is a necessary condition for the perception of pictures. If so, then animals, never exposed to situations in which those associations might be learned, should not show transfer between objects and pictures. In this investigation, pigeons trained to discriminate between two solid objects were retrained with reinforcement reversal on either the objects themselves or photographs, line drawings, or silhouettes of the objects. Significant negative transfer indicated object-photograph and object-silhouette equivalence, but no transfer was found to line drawings. Positive transfer to photographs was also demonstrated. Transfer did not appear to be a function of object-picture confusability.     

Chance results in utrocular discrimination

A review is made of studies on whether we know with which eye we are seeing. The almost total failure to achieve chance results is ascribed to lack of control of convergence and it is shown that such control completely eliminates discrimination.     

A theoretical comparison of list scanning models

Eight specific list scanning models are developed and relationships between predictions of contrasting models (serial versus parallel search, self-terminating versus exhaustive processing) are investigated. All models assume that items contained in a list are uniquely defined by specific features, and that the only process by which two items may be tested for equality is to compare corresponding features. All models predict RT to be linearly related with list length when no subject errors occur. With errors, some models predict theoretical nonlinearity but sample calculations indicate that deviation from linearity is slight in many cases. The importance of coding strategy is also discussed.     

Conditioned reinforcement: Experimental and theoretical issues

The concept of conditioned reinforcement has received decreased attention in learning textbooks over the past decade, in part because of criticisms of its validity by major behavior theorists and in part because its explanatory function in a variety of different conditioning procedures has become uncertain. Critical data from the major procedures that have been used to investigate the concept (second-order schedules, chain schedules, concurrent chains, observing responses, delay-of-reinforcement procedures) are reviewed, along with the major issues of interpretation. Although the role played by conditioned reinforcement in some procedures remains unresolved, the results taken together leave little doubt that the underlying idea of conditioned value is a critical component of behavior theory that is necessary to explain many different types of data. Other processes (marking, bridging) may also operate to produce effects similar to those of conditioned reinforcement, but these clearly cannot explain the full domain of experimental effects ascribed to conditioned reinforcement and should be regarded as complements to the concept rather than theoretical competitors. Examples of practical and theoretical applications of the concept of conditioned reinforcement are also considered.     

Assessment of suitability for low-fee control psychoanalysis: some theoretical and technical considerations

In the assessment of suitability for low-fee control analysis, various factors may interfere with successful referral, evaluation, and disposition. Variables within the referring analyst, patient, candidate, and supervisor are examined in their interaction with the circumstances of the assessment enterprise. Issues of competence, self-esteem, and oedipal rivalry, as well as guilt feelings, concerns about rejection, and other conflicts may be mobilized and may prevent a successful outcome. Clinical data from three assessments are presented and discussed. The concept of an assessment process, analogous to the psychoanalytic process, is proposed. In this process, manifestations of the patient's intrapsychic life and indicators of potential transferences emerge in the context of the analysis of the patient's reactions to the assessment. Potential sources of interference with the assessment process are identified, and measures to avoid them are suggested.     

Finite mixture distribution models of simple discrimination learning

Through the application of finite mixture distribution models, we investigated the existence of distinct modes of behavior in learning a simple discrimination. The data were obtained in a repeated measures study in which subjects aged 6 to 10 years carried out a simple discrimination learning task. In contrast to distribution models of exclusively rational learners or exclusively incremental learners, a mixture distribution model of rational learners and slow learners was found to fit the data of all measurement occasions and all age groups. Hence, the finite mixture distribution analysis provides strong support for the existence of distinct modes of learning behavior. The results of a second experiment support this conclusion by crossvalidation of the models that fit the data of the first experiment. The effect of verbally labeling the values on the relevant stimulus dimension and the consistency of behavior over measurement occasions are related to the mixture model estimates.     

Evolutionary models of color categorization based on discrimination

Specifying the factors that contribute to the universality of color categorization across individuals and cultures is a longstanding and still controversial issue in psychology, linguistics, and anthropology. This article approaches this issue through the simulated evolution of color lexicons. It is shown that the combination of a minimal perceptual psychology of discrimination, simple pragmatic constraints involving communication, and simple learning rules is enough to evolve color-naming systems. Implications of this result for psychological theories of color categorization and the evolution of color-naming systems in human societies are discussed.     

Accumulator and random-walk models of psychophysical discrimination: a counter-evaluation

In a recent assessment of models of psychophysical discrimination, Heath criticises the accumulator model for its reliance on computer simulation and qualitative evidence, and contrasts it unfavourably with a modified random-walk model, which yields exact predictions, is susceptible to critical test, and is provided with simple parameter-estimation techniques. A counter-evaluation is presented, in which the approximations employed in the modified random-walk analysis are demonstrated to be seriously inaccurate, the resulting parameter estimates to be artefactually determined, and the proposed test not critical. It is pointed out that Heath's specific application of the model is not legitimate, his data treatment inappropriate, and his hypothesis concerning confidence inconsistent with experimental results. Evidence from adaptive performance changes is presented which shows that the necessary assumptions for quantitative analysis in terms of the modified random-walk model are not satisfied, and that the model can be reconciled with data at the qualitative level only by making it virtually indistinguishable from an accumulator process. A procedure for deriving exact predictions for an accumulator process is outlined.     

Assessing the theoretical models for sex differences in causal attributions for success and failure

Three basic models of attributional sex differences are reviewed: General Externality, Self-Derogation, and Low Expectancy. Although all of the models predict that women are unlikely to attribute their successes to ability, the models were quite different in other predictions. A meta-analysis of 21 studies examining sex differences in success-failure attributions was done to determine which of these three models had the most empirical support. Wording of attribution questions was also assessed. Results indicated only two consistent sex differences: Men make stronger ability attributions than women regardless of the outcome when informational attributional wording is used; and men attribute their successes and failures less to luck. Empirically, none of the models was well supported.     

Completeness and conservative extension results for some boolean relevant logics

This paper presents completeness and conservative extension results for the boolean extensions of the relevant logic T of Ticket Entailment, and for the contractionless relevant logics TW and RW. Some surprising results are shown for adding the sentential constant t to these boolean relevant logics; specifically, the boolean extensions with t are conservative of the boolean extensions without t, but not of the original logics with t. The special treatment required for the semantic normality of T is also shown along the way.     

Nonparametric polytomous IRT models for invariant item ordering, with results for parametric models

It is often considered desirable to have the same ordering of the items by difficulty across different levels of the trait or ability. Such an ordering is an invariant item ordering (IIO). An IIO facilitates the interpretation of test results. For dichotomously scored items, earlier research surveyed the theory and methods of an invariant ordering in a nonparametric IRT context. Here the focus is on polytomously scored items, and both nonparametric and parametric IRT models are considered.The absence of the IIO property in twononparametric polytomous IRT models is discussed, and two nonparametric models are discussed that imply an IIO. A method is proposed that can be used to investigate whether empirical data imply an IIO. Furthermore, only twoparametric polytomous IRT models are found to imply an IIO. These are the rating scale model (Andrich, 1978) and a restricted rating scale version of the graded response model (Muraki, 1990). Well-known models, such as the partial credit model (Masters, 1982) and the graded response model (Samejima, 1969), do no imply an IIO.