Failure to construct and transfer correct representations across probability problems

Previous studies carried out on "purely random" situations (with dice or poker chips) show the difficulties encountered by people in such situations, however simple they may be. In fact, in this type of situation, prior knowledge guides spontaneous representations, and the "errors" observed could be explained by the activation of "implicit models" which form the basis of erroneous representations. 42 statistically na?ve undergraduates were given several variants of a probability problem on which errors are common. In a learning phase, subjects were given four problems involving geometric figures which were pairwise related by complementarity and equivalence relations. In a subsequent transfer phase, they were given a fifth problem involving poker chips, which was structurally isomorphic to the fourth geometric-figures problem. The findings show that people do not realize the relations between problems, and that transfer occurred only for the subset of subjects who performed correctly on the training problems of the learning phase. These results appear to have some significant implications in teaching mathematical concepts.     

Social anxiety in stuttering: measuring negative social expectancies

Much research has suggested that those who stutter are likely to be anxious. However, to date, little research on this topic has addressed the role of expectancies of harm in anxiety, which is a central construct of anxiety in modern clinical psychology. There are good reasons to believe that the anxiety of those who stutter is related to expectancies of social harm. Therefore, in the present study, 34 stuttering and 34 control participants completed the Fear of Negative Evaluation (FNE) Scale and the Endler Multidimensional Anxiety Scales-Trait (EMAS-T). The FNE data showed a significant difference between the stuttering and control participants, with a large effect size. Results suggested that, as a group, a clinical population of people who stutter has anxiety that is restricted to the social domain. For the EMAS-T, significant differences between groups were obtained for the two subtests that refer specifically to people and social interactions in which social evaluation might occur (Social Evaluation and New/Strange Situations) but not for the subtests that contained no specific reference to people and social interactions (Physical Danger and Daily Routines). These results were taken to suggest that those who stutter differ from control subjects in their expectation of negative social evaluation, and that the effect sizes are clinically significant. The findings also suggest that the FNE and the EMAS-T are appropriate psychological tests of anxiety to use with stuttering clients in clinical settings. The clinical and research implications of these findings are discussed, in terms of whether social anxiety mediates stuttering or is a simple by-product of stuttering. Possible laboratory explorations of this issue are suggested, and potential Cognitive Behavior Therapy packages for stuttering clients who might need them are discussed. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) explain why expectancy of social threat or harm may be associated with stuttering; (2) name and describe two psychological tests that are suitable for assessment of the social threat or harm that may be associated with stuttering; and (3) explain how findings for the EMAS-T test in the present results suggest that expectancy of social threat or harm, but not other kinds of negative expectancy, are associated with stuttering.     

Negative compatibility or object updating? A cautionary tale of mask-dependent priming

The negative compatibility effect (NCE) is the surprising result that visual targets that follow a brief prime stimulus and a mask can be identified more rapidly when they are opposite rather than identical to the prime. In a recent article in this journal, S. T. Klapp and L. B. Hinkley (2002) proposed that this reflected a competition between inhibitory unconscious processes and excitatory conscious processes. The authors of the current article report 7 experiments with results countering this theory and propose an alternative account within the framework of object substitution masking. In this account, the NCE reflects the updating of perceptual objects, including their links to responses closely associated with those objects.     

Absence of an interaction between navigational strategies based on local and distal landmarks

In 3 experiments, rats were required to escape from a Morris pool by swimming to a submerged platform that was located at the apex of a notional, equilateral triangle with 2 different landmarks occupying the corners at the base. Training for 1 group was always conducted in view of the landmarks surrounding the pool and with the triangular array in a fixed orientation. Subjects could therefore identify the direction of the platform from a single landmark within the pool by reference to cues outside the pool or to the other landmark within the pool. Both strategies were used, and the results from additional groups revealed that the first of these strategies did not affect the acquisition of the second one.     

Transfer of spatial behavior between different environments: implications for theories of spatial learning and for the role of the hippocampus in spatial learning

In 3 experiments, rats were required to find a submerged platform located in 1 corner of an arena that had 2 long and 2 short sides; they were then trained to find the platform in a new arena that also had 2 long and 2 short sides but a different overall shape. The platform in the new arena was easier to find if it was in a corner that was geometrically equivalent, rather than the mirror image, of the corner where it had previously been located. The final experiment revealed that hippocampal lesions impaired rats' ability to find the platform in these arenas. The results suggest that rats did not use the overall shape of the arena to locate the platform but relied on more local cues and that the hippocampus plays a role in navigation based on these cues.     

Panoramic search: the interaction of memory and vision in search through a familiar scene

How do observers search through familiar scenes? A novel panoramic search method is used to study the interaction of memory and vision in natural search behavior. In panoramic search, observers see part of an unchanging scene larger than their current field of view. A target object can be visible, present in the display but hidden from view, or absent. Visual search efficiency does not change after hundreds of trials through an unchanging scene (Experiment 1). Memory search, in contrast, begins inefficiently but becomes efficient with practice. Given a choice between vision and memory, observers choose vision (Experiments 2 and 3). However, if forced to use their memory on some trials, they learn to use memory on all trials, even when reliable visual information remains available (Experiment 4). The results suggest that observers make a pragmatic choice between vision and memory, with a strong bias toward visual search even for memorized stimuli.     

Test-retest reliability of fMRI during nonverbal semantic decisions in moderate-severe nonfluent aphasia patients

Cortical reorganization in poststroke aphasia is not well understood. Few studies have investigated neural mechanisms underlying language recovery in severe aphasia patients, who are typically viewed as having a poor prognosis for language recovery. Although test-retest reliability is routinely demonstrated during collection of language data in single-subject aphasia research, this is rarely examined in fMRI studies investigating the underlying neural mechanisms in aphasia recovery. The purpose of this study was to acquire fMRI test-retest data examining semantic decisions both within and between two aphasia patients. Functional MRI was utilized to image individuals with chronic, moderate-severe nonfluent aphasia during nonverbal, yes/no button-box semantic judgments of iconic sentences presented in the Computer-assisted Visual Communication (C-ViC) program. We investigated the critical issue of intra-subject reliability by exploring similarities and differences in regions of activation during participants' performance of identical tasks twice on the same day. Each participant demonstrated high intra-subject reliability, with response decrements typical of task familiarity. Differences between participants included greater left hemisphere perilesional activation in the individual with better response to C-ViC training. This study provides fMRI reliability in chronic nonfluent aphasia, and adds to evidence supporting differences in individual cortical reorganization in aphasia recovery.     

Decision-making impairments in patients with Parkinson's disease

A high percentage of Parkinson's disease (PD) patients show cognitive impairments in addition to the cardinal motor symptoms. These deficits primarily concern executive functions most probably linked to dysfunctions in prefrontal regions due to decreased dopaminergic transmission in fronto-striatal loops. To investigate possible associations between decision-making and executive functions in PD, we examined 20 non-demented PD patients and 20 healthy control subjects with a neuropsychological test battery and the Game of Dice Task. In this computerised decision-making task, the rules for gains and losses and the winning probabilities are obvious and stable. Thus, strategic components besides feedback processing might influence decision-making in this task. We found that PD patients were impaired in the Game of Dice task performance and that the frequency of disadvantageous choices correlated with both executive functions and feedback processing. We suggest that decision-making deficits of PD patients in explicit gambling situations might be associated with dysfunctions in two different fronto-striatal loops: the limbic-orbitofrontal-striatal loop, involved in feedback processing, and the dorsolateral prefrontal-striatal loop, involved in executive functions.     

Training-based interventions in motor rehabilitation after stroke: theoretical and clinical considerations

Basic neuroscience research on brain plasticity, motor learning and recovery has stimulated new concepts in neurological rehabilitation. Combined with the development of set methodological standards in clinical outcome research, these findings have led to a double-paradigm shift in motor rehabilitation: (a) the move towards evidence-based procedures for the assessment of clinical outcome & the employment of disablement models to anchor outcome parameters, and (b) the introduction of practice-based concepts that are derived from testable models that specify treatment mechanisms. In this context, constraint-induced movement therapy (CIT) has played a catalytic role in taking motor rehabilitation forward into the scientific arena. As a theoretically founded and hypothesis-driven intervention, CIT research focuses on two main issues. The first issue is the assessment of long-term clinical benefits in an increasing range of patient groups, and the second issue is the investigation of neuronal and behavioural treatment mechanisms and their interactive contribution to treatment success. These studies are mainly conducted in the research environment and will eventually lead to increased treatment benefits for patients in standard health care. However, gradual but presumably more immediate benefits for patients may be achieved by introducing and testing derivates of the CIT concept that are more compatible with current clinical practice. Here, we summarize the theoretical and empirical issues related to the translation of research-based CIT work into the clinical context of standard health care.     

The role of gestures in spatial working memory and speech

Co-speech gestures traditionally have been considered communicative, but they may also serve other functions. For example, hand-arm movements seem to facilitate both spatial working memory and speech production. It has been proposed that gestures facilitate speech indirectly by sustaining spatial representations in working memory. Alternatively, gestures may affect speech production directly by activating embodied semantic representations involved in lexical search. Consistent with the first hypothesis, we found participants gestured more when describing visual objects from memory and when describing objects that were difficult to remember and encode verbally. However, they also gestured when describing a visually accessible object, and gesture restriction produced dysfluent speech even when spatial memory was untaxed, suggesting that gestures can directly affect both spatial memory and lexical retrieval.