Phonological processing of words in right- and left-handers

It is commonly accepted that phonology is the exclusive domain of the left hemisphere. However, this pattern of lateralization, which posits a right visual field advantage, has been questioned by several studies. In fact, certain factors such as characteristics of the stimuli and subjects' handedness can modulate the right visual field advantage. Thus, the goal of this study was to compare the hemispheric dynamics of right-handers and left-handers during a divided visual field presentation of words that varied in terms of their phonological transparency. For non-transparent words, the left hemisphere seems more competent in both handedness groups. With regard to transparent words, the right hemisphere of both groups also appears competent. Surprisingly, left-handers achieved optimal processing with a functionally isolated left hemisphere, whereas right-handers needed the participation of both hemispheres. The pattern of performance cannot be fully explained by either the callosal or the direct access model.     

Mixture Models of Categorization

Many currently popular models of categorization are either strictly parametric (e.g., prototype models, decision bound models) or strictly nonparametric (e.g., exemplar models) (F. G. Ashby & L. A. Alfonso-Reese, 1995, Journal of Mathematical Psychology, 39, 216-233). In this article, a family of semiparametric classifiers is investigated where categories are represented by a finite mixture distribution. The advantage of these mixture models of categorization is that they contain several parametric models and nonparametric models as a special case. Specifically, it is shown that both decision bound models (F. G. Ashby & W. T. Maddox, 1992, Journal of Experimental Psychology: Human Perception and Performance, 16, 598-612; 1993, Journal of Mathematical Psychology, 37, 372-400) and the generalized context model (R. M. Nosofsky, 1986, Journal of Experimental Psychology: General, 115, 39-57) can be interpreted as two extreme cases of a common mixture model. Furthermore, many other (semiparametric) models of categorization can be derived from the same generic mixture framework. In this article, several examples are discussed and a parameter estimation procedure for fitting these models is outlined. To illustrate the approach, several specific models are fitted to a data set collected by S. C. McKinley and R. M. Nosofsky (1995, Journal of Experimental Psychology: Human Perception and Performance, 21, 128-148). The results suggest that semi-parametric models are a promising alternative for future model development.     

Self-Esteem, Mood, and Intentions to Use Condoms: When Does Low Self-Esteem Lead to Risky Health Behaviors?

The authors assessed the interactive effects of self-esteem and mood on intentions to engage in unprotected sexual intercourse. Prior research has shown that people with low self-esteem tend to evaluate themselves unfavorably when in a negative mood state, whereas people with high self-esteem are less susceptible to changes in self-evaluation following a negative mood induction. The authors hypothesized that people who engage in negative self-evaluations may be more likely to report intentions to engage in unprotected sexual intercourse. Undergraduate females were randomly assigned to a positive or negative mood induction condition. Consistent with their hypotheses, the authors found that among participants who were in a negative mood state, those with low self-esteem were more likely to report intentions to have sexual intercourse without a condom than were those with high self-esteem. In contrast, among participants in a positive mood, there were no differences between those who were low and high in self-esteem.     

Fruits and vegetables categorized: an application of the generalized context model

In the study reported in this paper, we investigated the categorization of well-known and novel food items in the categories fruits and vegetables. Predictions based on Nosofsky’s (1984, 1986) generalized context model (GCM), on a multiplicative-similarity prototype model, and on an instantiation model as applied in Storms, De Boeck, and Ruts (2001) were compared. Despite suggestions in the literature that prototype models predict categorization from large categories better than exemplar models do, our results showed that the exemplar-based GCM yielded clearly better predictions than did a (multiplicative-similarity) prototype model.     

Impact of right hemispheric damage on a hierarchy of complexity evidenced in young normal subjects

The occurrence of a right-hemisphere lesion can interfere with pragmatic abilities and particularly with the processing of non-literal speech acts in which the listener has to identify the speaker's intention. The aim of this study was to test RHD subjects' ability to process non-literal speech acts. A chronometric approach to RHD and matched control performance showed that RHD subjects are impaired in the processing of non-literal speech, though they are also sensitive to the hierarchy of complexity among types. Only the processing of indirect speech acts was not shown to differ from that of normals, probably because the stimuli were of the conventional type. These results show the relevancy of a chronometric approach. They also emphasize the importance of further studying RHD subjects' ability to attribute intentions to protagonists in a short story.     

Choice and response time processes in the identification and categorization of unidimensional stimuli

Lacouture and Marley (1991, 1995, 2001) have successfully modeled the probabilities of correct responses and the mean correct response times (RTs) in unidimensional absolute identification tasks for various stimulus ranges and stimulus/response set sizes, for individual and group data. These fits include those to a set of phenomena often referred to as end-anchor effects. A revised model, with the independent accumulator decision process replaced by a leaky competing accumulator decision process, fits the probabilities of correct responses and the full distributions of RTs in unidimensional absolute identification. The revised model is also applied successfully to a particular class of unidimensional categorization tasks. We discuss possible extensions for handling sequential effects in unidimensional absolute identification, and other extensions of the given class of categorization tasks that are of potential empirical and theoretical importance as a supplement to the study of multidimensional absolute identification tasks.     

Estimating Structural Equation Models Using James–Stein Type Shrinkage Estimators

Psychometrika - We propose a two-step procedure to estimate structural equation models (SEMs). In a first step, the latent variable is replaced by its conditional expectation given the observed...     

Atypical inter‐hemispheric communication correlates with altered motor inhibition during learning of a new bimanual coordination pattern in developmental coordination disorder

Impairment of motor learning skills in developmental coordination disorder (DCD) has been reported in several studies. Some hypotheses on neural mechanisms of motor learning deficits in DCD have emerged but, to date, brain‐imaging investigations are scarce. The aim of the present study is to assess possible changes in communication between brain areas during practice of a new bimanual coordination task in teenagers with DCD (n = 10) compared to matched controls (n = 10). Accuracy, stability and number of mirror movements were computed as behavioural variables. Neural variables were assessed by electroencephalographic coherence analyses of intra‐hemispheric and inter‐hemispheric fronto‐central electrodes. In both groups, accuracy of the new coordination increased concomitantly with right intra‐hemispheric fronto‐central coherence. Compared to typically developing teenagers, DCD teenagers presented learning difficulties expressed by less stability, no stabilization of the new coordination and a greater number of mirror movements despite practice. These measures correlated with reduced inter‐hemispheric communication, even after practice of the new coordination. For the first time, these findings provide neuro‐imaging evidence of a kind of inter‐hemispheric ‘disconnection’ related to altered inhibition of mirror movements during motor learning in DCD.