An early electrophysiological response associated with expertise in letter perception

Expertise with print is likely to optimize visual processes for recognizing characters of a familiar writing system. Although brain activations have been identified for words and letter strings in contrast with other stimuli, relatively little work has focused on the neural basis of single-letter perception. English readers and Chinese-English bilinguals participated in an ERP study and performed a 1-back identity judgment on Roman letters, Chinese characters, pseudofonts, and their string versions. The Chinese-English bilinguals showed an enhanced N170 for both Roman letters and Chinese characters relative to pseudofonts. For the non-Chinese readers, the N170 amplitude was larger for Roman letters relative to Chinese characters and pseudofonts. Our results suggest that changes in relatively early visual processes underlie expert letter perception.     

Belief-desire reasoning as a process of selection

Human learning may depend upon domain specialized mechanisms. A plausible example is rapid, early learning about the thoughts and feelings of other people. A major achievement in this domain, at about age four in the typically developing child, is the ability to solve problems in which the child attributes false beliefs to other people and predicts their actions. The main focus of theorizing has been why 3-year-olds fail, and only recently have there been any models of how success is achieved in false-belief tasks. Leslie and Polizzi (Inhibitory processing in the false-belief task: Two conjectures. Developmental Science, 1, 247-254, 1998) proposed two competing models of success, which are the focus of the current paper. The models assume that belief-desire reasoning is a process which selects a content for an agent's belief and an action for the agent's desire. In false belief tasks, the theory of mind mechanism (ToMM) provides plausible candidate belief contents, among which will be a 'true-belief.' A second process reviews these candidates and by default will select the true-belief content for attribution. To succeed in a false-belief task, the default content must be inhibited so that attention shifts to another candidate belief. In traditional false-belief tasks, the protagonist's desire is to approach an object. Here we make use of tasks in which the protagonist has a desire to avoid an object, about which she has a false-belief. Children find such tasks much more difficult than traditional tasks. Our models explain the additional difficulty by assuming that predicting action from an avoidance desire also requires an inhibition. The two processing models differ in the way that belief and desire inhibitory processes combine to achieve successful action prediction. In six experiments we obtain evidence favoring one model, in which parallel inhibitory processes cancel out, over the other model, in which serial inhibitions force attention to a previously inhibited location. These results are discussed in terms of a set of simple proposals for the modus operandi of a domain specific learning mechanism. The learning mechanism is in part modular--the ToMM--and in part penetrable--the Selection Processor (SP). We show how ToMM-SP can account both for competence and for successful and unsuccessful performance on a wide range of belief-desire tasks across the preschool period. Together, ToMM and SP attend to and learn about mental states.     

Putting some feeling into it--the conceptual and empirical relationships between the classic and emotional Stroop tasks: comment on Algom, Chajut, and Lev (2004)

D. Algom, E. Chajut, and S. Lev presented a series of definitional, conceptual, and empirical arguments in support of their conclusion that the classic and emotional Stroop effects are, in their words, "unrelated phenomena" (p. 336), such that the term emotional Stroop effect is a misnomer in reference to the relatively greater interference in ink color naming of emotional versus neutral words. These are strong claims. In this comment, the author critically examines each component of Algom et al.'s case and argues that, in fact, none of these components represents compelling evidence in support of their eventual conclusions.     

Pitch perception in children with autistic spectrum disorders

This study investigated the accuracy of musical pitch detection in children with autistic spectrum disorders as compared with typically developing children. Seventeen children on the autistic spectrum (M(age) =9.34, SD(age) =1.12) and 13 typically developing, chronological age-matched children (M(age) =9.13, SD(age) =1.68) took part in the current study. Children were required to listen to four tones, which were paired with four different pictures and asked to learn the combinations. The children were then assessed for their ability to identify the previously learned tones, when they were presented as single tones and when they were embedded in chords and discords. No significant group differences were found. However, after subdividing the clinical group according to their diagnosis of autism or Asperger's syndrome, the results indicated a slightly superior disembedding ability in participants with Asperger's syndrome. The findings are discussed in terms of the weak central coherence concept.     

Amputees by choice: body integrity identity disorder and the ethics of amputation

ABSTRACT Should surgeons be permitted to amputate healthy limbs if patients request such operations? We argue that if such patients are experiencing significant distress as a consequence of the rare psychological disorder named Body Integrity Identity Disorder (BIID), such operations might be permissible. We examine rival accounts of the origins of the desire for healthy limb amputations and argue that none are as plausible as the BIID hypothesis. We then turn to the moral arguments against such operations, and argue that on the evidence available, none is compelling. BIID sufferers meet reasonable standards for rationality and autonomy: so as long as no other effective treatment for their disorder is available, surgeons ought to be allowed to accede to their requests.     

Evaluating three criteria for establishing cue-search hierarchies in inferential judgment

The authors identify and provide an integration of 3 criteria for establishing cue-search hierarchies in inferential judgment. Cues can be ranked by information value according to expected information gain (Bayesian criterion), cue-outcome correlation (correlational criterion), or ecological validity (accuracy criterion). All criteria significantly predicted information acquisition behavior; however, in 3 experiments, the most successful predictor was the correlational criterion (followed by the Bayesian). Although participants showed sensitivity to task constraints, searching for less information when it was more expensive (Experiment 1) and when under time constraints (Experiment 2), concomitant changes in the relative frequency of acquisition of cues with different information values were not observed. A rational analysis illustrates why such changes in the frequency of acquisition would be beneficial, and reasons for the failure to observe such behavior are discussed.     

Perceptual and lexical components of auditory repetition priming in young and older adults

In the present study, we examined whether age modulates the processing of lexical and perceptual information in auditory implicit and explicit memory tests. Young and older adults performed a surface encoding task on spoken and printed words and then either identified degraded words or made explicit recognition judgments. The implicit test of perceptual identification yielded no evidence of age-related declines in the processing of either lexical information or coarse perceptual details (modality of presentation). The same test, however, produced marked age-related declines in the processing of fine-grained perceptual details (voice) when subjects were not familiarized with the talkers' voices prior to the encoding task. Marked age differences were also observed in recognition memory. These findings suggest that although aging preserves the encoding and incidental retrieval of lexical and coarse perceptual information, it affects the encoding of fine-grained perceptual information and deliberate retrieval processes.     

Three-dimensional angular kinematics of the lumbar spine and pelvis during running

The objective of this study were to: (i) describe the typical three-dimensional (3D) angular kinematics of the lumbar spine and pelvis during running and; (ii) assess whether the movements of the lumbar spine and pelvis during running are coordinated. A cohort of 20 non-injured male runners who usually ran >20 km/week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m/second. Reflective markers were placed over anatomical landmarks of the thoraco-lumbar spine and pelvis. Data were captured using a VICON motion analysis system. The lumbar spine and pelvis both displayed complex 3D angular kinematic patterns during running. High correlations were found for the comparisons of flexion-extension of the lumbar spine with anterior-posterior tilt of the pelvis (r=-0.84) and lateral bend of the lumbar spine with obliquity of the pelvis (r=-0.75). However, a poor correlation was found for the comparison of axial rotation of the lumbar spine with axial rotation of the pelvis (r=0.37). A phase difference of 21% of the running cycle was evident between axial rotation of the lumbar spine and pelvis. The identified coordinated kinematic patterns of the lumbar spine and pelvis during running serve as a basis for future investigations exploring the relationship between atypical kinematic patterns and injury.     

Visuoperceptual and visuomotor deficits in developmental stutterers: an exploratory study

Although the cause of stuttering is unknown, there is strong evidence for it being a neuromotor disorder characterised by an abnormality of higher control encompassing not only speech but other motor systems. The aim of this exploratory study was to look for the presence of non-speech/language deficits--in particular, visuomotor and visuoperceptual deficits--in persons who stutter. Twelve moderate to severe developmental stutterers were compared with a group of fluent speakers, matched for age and sex, on a range of computerized sensory-motor tasks. These tasks covered various aspects of visuomotor function--ballistic movement, dynamic steadiness, and several types of tracking--and visuoperceptual function--acuity, static perception, and dynamic perception. A novel technique was used to remove the visuospatial component from tracking performance. Stutterers had slower reaction times, less accurate random tracking, and impaired dynamic visual perception. Severity of stuttering correlated with reaction time and dynamic perception. Removal of the visuoperceptual component from tracking performance indicated that the impaired tracking in the stutterers was predominantly due to reduced dynamic perception. This is the first study to provide preliminary evidence for the presence of non-linguistic visuoperceptual and upper-limb visuomotor tracking deficits in people with moderate to severe stuttering. These findings support a neurogenic aetiology for stuttering and are compatible with evidence of an overactive dopamine system in stutterers.     

Observed classroom behavior of children with ADHD: relationship to gender and comorbidity

Examined hypothesized gender and comorbidity differences in the observed classroom behavior of children with attention deficit hyperactivity disorder (ADHD). The behavior of 403 boys and 99 girls with ADHD, ages 7–10, was compared (a) to observed, sex-specific classroom behavior norms, (b) by sex, and (c) by comorbid subgroups. Boys and girls with ADHD deviated significantly from classroom norms on 15/16 and 13/16 categories, respectively. Compared to comparison girls, girls with ADHD had relatively high rates of verbal aggression to children. Boys with ADHD engaged in more rule-breaking and externalizing behaviors than did girls with ADHD, but the sexes did not differ on more neutral, unobtrusive behaviors. The sex differences are consistent with notions of why girls with ADHD are identified and referred later than boys. Contrary to hypothesis, the presence of comorbid anxiety disorder (ANX) was not associated with behavioral suppression; yet, as hypothesized, children with a comorbid disruptive behavior disorder (DBD) had higher rates of rule-breaking, and impulsive and aggressive behavior, than did children with ADHD alone and those with ADHD+ANX. Elevated rates of ADHD behaviors were also observed in children with comorbid DBD, indicating that these behaviors are truly present and suggesting that reports of higher ADHD ratings in this subgroup are not simply a consequence of negative halo effects and rater biases.