Discrimination of speech sounds by children with dyslexia: comparisons with chronological age and reading level controls

Previous studies have shown that children suffering from developmental dyslexia have a deficit in categorical perception of speech sounds. The aim of the current study was to better understand the nature of this categorical perception deficit. In this study, categorical perception skills of children with dyslexia were compared with those of chronological age and reading level controls. Children identified and discriminated /do-to/ syllables along a voice onset time (VOT) continuum. Results showed that children with dyslexia discriminated among phonemically contrastive pairs less accurately than did chronological age and reading level controls and also showed higher sensitivity in the discrimination of allophonic contrasts. These results suggest that children with dyslexia perceive speech with allophonic units rather than phonemic units. The origin of allophonic perception in the course of perceptual development and its implication for reading acquisition are discussed.     

The role of representational status and item complexity in parent–child conversations about pictures and objects

Mother–child conversations about pictures systematically differ from mother–child conversations about objects: Pictures are more likely than objects to elicit talk about kinds, whereas objects are more likely than pictures to elicit talk about individuals. The purpose of the current study is to examine whether this difference between pictures and objects is explained by differences in item complexity. Mothers and their 4-year-old children were randomly assigned to one of two conditions: simple or complex. In each condition, participants viewed 12 toy objects and 12 pictures, matched for content. The items were either highly detailed (complex condition) or very plain (simple condition). Replicating previous research, mothers and children provided relatively more focus on kinds when talking about pictures, and relatively more focus on individuals when talking about objects. The current results go further, however, to demonstrate that this effect is independent of the items’ complexity. We therefore propose that the picture–object difference is not due to low-level differences in amount of perceptual detail provided, but rather is due to the greater ease with which pictures serve as representations [DeLoache, J. S. (1991). Symbolic functioning in very young children: Understanding of pictures and models. Child Development, 62, 736–752]. These data indicate the ways in which a fundamental conceptual distinction between kinds and individuals arises in different linguistic expressions and in different contexts.     

Categorical Perception Beyond the Basic Level: The Case of Warm and Cool Colors

Categories can affect our perception of the world, rendering between‐category differences more salient than within‐category ones. Across many studies, such categorical perception (CP) has been observed for the basic‐level categories of one's native language. Other research points to categorical distinctions beyond the basic level, but it does not demonstrate CP for such distinctions. Here we provide such a demonstration. Specifically, we show CP in English speakers for the non‐basic distinction between “warm” and “cool” colors, claimed to represent the earliest stage of color lexicon evolution. Notably, the advantage for discriminating colors that straddle the warm–cool boundary was restricted to the right visual field—the same behavioral signature previously observed for basic‐level categories. This pattern held in a replication experiment with increased power. Our findings show that categorical distinctions beyond the basic‐level repertoire of one's native language are psychologically salient and may be spontaneously accessed during normal perceptual processing.     

Individual differences in spatial relation processing: effects of strategy, ability, and gender

Numerous studies have focused on the distinction between categorical and coordinate spatial relations. Categorical relations are propositional and abstract, and often related to a left hemisphere advantage. Coordinate relations specify the metric information of the relative locations of objects, and can be linked to right hemisphere processing. Yet, not all studies have reported such a clear double dissociation; in particular the categorical left hemisphere advantage is not always reported. In the current study we investigated whether verbal and spatial strategies, verbal and spatial cognitive abilities, and gender could account for the discrepancies observed in hemispheric lateralization of spatial relations. Seventy-five participants performed two visual half field, match-to-sample tasks (Van der Ham, van Wezel, Oleksiak, & Postma, 2007; Van der Ham, Raemaekers, van Wezel, Oleksiak, and Postma, 2009) to study the lateralization of categorical and coordinate relation processing. For each participant we determined the strategy they used in each of the two tasks. Consistent with previous findings, we found an overall categorical left hemisphere advantage and coordinate right hemisphere advantage. The lateralization pattern was affected selectively by the degree to which participants used a spatial strategy and by none of the other variables (i.e., verbal strategy, cognitive abilities, and gender). Critically, the categorical left hemisphere advantage was observed only for participants that relied strongly on a spatial strategy. This result is another piece of evidence that categorical spatial relation processing relies on spatial and not verbal processes.     

Building and solving odd-one-out classification problems: A systematic approach

Classification problems (“find the odd-one-out”) are frequently used as tests of inductive reasoning to evaluate human or animal intelligence. This paper introduces a systematic method for building the set of all possible classification problems, followed by a simple algorithm for solving the problems of the R-ASCM, a psychometric test derived from this method. The average Hamming distance finds repetitions of features between and within the problems' sets; it manages to solve 97% of such problems. This performance is equaled only by superior human adults. Finally, these results demonstrate that a simple two-step algorithm can improve categorical case-based reasoning and k-NN algorithms while clarifying the cognitive basis of classification.     

Contributions to Estimation of Polychoric Correlations

This research concerns the estimation of polychoric correlations in the context of fitting structural equation models to observed ordinal variables by multistage estimation. The first main contribution of this research is to propose and evaluate a Monte Carlo estimator for the asymptotic covariance matrix (ACM) of the polychoric correlation estimates. In multistage estimation, the ACM plays a prominent role, as overall test statistics, derived fit indices, and parameter standard errors all depend on this quantity. The ACM, however, must itself be estimated. Established approaches to estimating the ACM use a sample-based version, which can yield poor estimates with small samples. A simulation study demonstrates that the proposed Monte Carlo estimator can be more efficient than its sample-based counterpart. This leads to better calibration for established test statistics, in particular with small samples. The second main contribution of this research is a further exploration of the consequences of violating the normality assumption for the underlying response variables. We show the consequences depend on the type of nonnormality, and the number and location of thresholds. The simulation study also demonstrates that overall test statistics have little power to detect the studied forms of nonnormality, regardless of the ACM estimator.     

Seeking Perfection: A Kantian Look at Human Genetic Engineering

It is tempting to argue that Kantian moral philosophy justifies prohibiting both human germ-line genetic engineering and non-therapeutic genetic engineering because they fail to respect human dignity. There are, however, good reasons for resisting this temptation. In fact, Kant’s moral philosophy provides reasons that support genetic engineering—even germ-line and non-therapeutic. This is true of Kant’s imperfect duties to seek one’s own perfection and the happiness of others. It is also true of the categorical imperative. Kant’s moral philosophy does, however, provide limits to justifiable genetic engineering.     

Predictive and postdictive mechanisms jointly contribute to visual awareness

One of the fundamental issues in visual awareness is how we are able to perceive the scene in front of our eyes on time despite the delay in processing visual information. The prediction theory postulates that our visual system predicts the future to compensate for such delays. On the other hand, the postdiction theory postulates that our visual awareness is inevitably a delayed product. In the present study we used flash-lag paradigms in motion and color domains and examined how the perception of visual information at the time of flash is influenced by prior and subsequent visual events. We found that both types of event additively influence the perception of the present visual image, suggesting that our visual awareness results from joint contribution of predictive and postdictive mechanisms.     

Categorical perception of affective and linguistic facial expressions

Two experiments investigated categorical perception (CP) effects for affective facial expressions and linguistic facial expressions from American Sign Language (ASL) for Deaf native signers and hearing non-signers. Facial expressions were presented in isolation (Experiment 1) or in an ASL verb context (Experiment 2). Participants performed ABX discrimination and identification tasks on morphed affective and linguistic facial expression continua. The continua were created by morphing end-point photo exemplars into 11 images, changing linearly from one expression to another in equal steps. For both affective and linguistic expressions, hearing non-signers exhibited better discrimination across category boundaries than within categories for both experiments, thus replicating previous results with affective expressions and demonstrating CP effects for non-canonical facial expressions. Deaf signers, however, showed significant CP effects only for linguistic facial expressions. Subsequent analyses indicated that order of presentation influenced signers’ response time performance for affective facial expressions: viewing linguistic facial expressions first slowed response time for affective facial expressions. We conclude that CP effects for affective facial expressions can be influenced by language experience.     

The application of correspondence analysis to multiple-criteria decision making

The aim of this paper is to show how correspondence analysis can be a useful aid in multiple-criteria decision making, particularly in the case of categorical criteria values. Under different types of input information, the technique is used to perform some preliminary analyses with a bonus of providing a simultaneous graphical representation of the alternatives and criteria. This picture can provide a better understanding of the structure of the two sets of variables to the decision maker before a decision is made.