A quantitative evaluation of the AVITEWRITE model of handwriting learning

Much sensory-motor behavior develops through imitation, as during the learning of handwriting by children. Such complex sequential acts are broken down into distinct motor control synergies, or muscle groups, whose activities overlap in time to generate continuous, curved movements that obey an inverse relation between curvature and speed. The adaptive vector integration to endpoint handwriting (AVITEWRITE) model of Grossberg and Paine (2000) [A neural model of corticocerebellar interactions during attentive imitation and predictive learning of sequential handwriting movements. Neural Networks, 13, 999-1046] addressed how such complex movements may be learned through attentive imitation. The model suggested how parietal and motor cortical mechanisms, such as difference vector encoding, interact with adaptively-timed, predictive cerebellar learning during movement imitation and predictive performance. Key psychophysical and neural data about learning to make curved movements were simulated, including a decrease in writing time as learning progresses; generation of unimodal, bell-shaped velocity profiles for each movement synergy; size scaling with isochrony, and speed scaling with preservation of the letter shape and the shapes of the velocity profiles; an inverse relation between curvature and tangential velocity; and a two-thirds power law relation between angular velocity and curvature. However, the model learned from letter trajectories of only one subject, and only qualitative kinematic comparisons were made with previously published human data. The present work describes a quantitative test of AVITEWRITE through direct comparison of a corpus of human handwriting data with the model's performance when it learns by tracing the human trajectories. The results show that model performance was variable across the subjects, with an average correlation between the model and human data of 0.89+/-0.10. The present data from simulations using the AVITEWRITE model highlight some of its strengths while focusing attention on areas, such as novel shape learning in children, where all models of handwriting and the learning of other complex sensory-motor skills would benefit from further research.     

Identity but not expression memory for unfamiliar faces is affected by ageing

We examined age-related differences in memory for identity and emotional expression of unfamiliar faces. Younger and older adults were presented with happy and angry faces and were later asked to recognise the same faces displaying a neutral expression. When a face was recognised, they also had to remember what the initial expression of the face had been. In addition, states of awareness associated with both identity and expression memory were assessed with the remember/know/guess paradigm. Older adults showed less recollective experience than younger adults for identity but not for emotional expressions of the faces. This evidence indicates that age-related differences in memory may depend on the nature of the to-be-remembered information, with emotional/social information being remembered as well in older as in younger adults.     

Speculation about behavior, brain damage, and self-organization: the other way to herd a cat

This article contrasts aphasic patients' performance of word naming and lexical decision with that of intact college-aged readers. We discuss this contrast within a framework of self-organization; word recognition by aphasic patients is destabilized relative to intact performance. Less stable performance shows itself as an increase in the dispersion of patients' response times compared to college students'. Dispersion is also more pronounced for low-frequency words than for high frequency words. We speculate, that increased dispersion originates in a reduction of constraints that support naming and lexical decision performances. A sufficient reduction of constraints yields qualitative changes in performance such as the production of semantic errors in deep dyslexia. These hypotheses are offered as alternatives to postulating distinct modules.     

Evidence for an Error Monitoring Deficit in Attention Deficit Hyperactivity Disorder

We studied error monitoring in ADHD and control children in a task requiring inhibition of a motor response. The extent of slowing following successful (stopped) and failed (nonstopped) inhibition was compared across groups. We also measured the time required to inhibit a response (stop signal reaction time, SSRT). Compared to controls, ADHD participants slowed less following nonstopped responses. Slowing did not vary with comorbid reading, oppositional, conduct or anxiety disorder, sex or ADHD subtype. Slowing after nonstopped responses was marginally, although significantly correlated with total ADHD symptoms and with age. ADHD participants had significantly longer SSRT than controls, but SSRT was not significantly correlated with slowing. The apparent deficit in error monitoring in ADHD and its independence from the inhibition deficit observed in ADHD has implications for executive control models of ADHD, performance problems associated with the disorder and for component theories of executive control.     

The role of nonautomatic processes in activity regulation: from Lipps to Galperin

The authors present the historical analysis of one of the central questions in psychology: how and why the nonautomatic, psychological level of regulation (in contrast to automatic physiological processes) emerges both in evolution and in everyday context of activity. They discuss several approaches (by Lipps, Groos, Stern, James, Dewey, Claparède, Pavlov, and Leontiev) that culminated in the system of ideas developed by Galperin, one of the key figures in the cultural -historical activity theory. The authors analyze the relation of Galperin's ideas to Vygotsky's theoretical framework and then focus on Galperin's account of the origin and functions of mental activity. Galperin's contribution is highly relevant for understanding the role of psychological regulation and for contemporary research on cognition, consciousness, and conscious awareness.     

Improving fairness in coverage decisions: performance expectations for quality improvement

Patients and physicians often perceive the current health care system to be unfair, in part because of the ways in which coverage decisions appear to be made. To address this problem the Ethical Force Program, a collaborative effort to create quality improvement tools for ethics in health care, has developed five content areas specifying ethical criteria for fair health care benefits design and administration. Each content area includes concrete recommendations and measurable expectations for performance improvement, which can be used by those organizations involved in the design and administration of health benefits packages, such as purchasers, health plans, benefits consultants, and practitioner groups.     

Identity and expression memory for happy and angry faces in social anxiety

We examined the influence of social anxiety on memory for both identity and emotional expressions of unfamiliar faces. Participants high and low in social anxiety were presented with happy and angry faces and were later asked to recognise the same faces displaying a neutral expression. They also had to remember what the initial expressions of the faces had been. Remember/know/guess judgements were asked both for identity and expression memory. For participants low in social anxiety, both identity and expression memory were more often associated with "remember" responses when the faces were previously seen with a happy rather than an angry expression. In contrast, the initial expression of the faces did not affect either identity or expression memory for participants high in social anxiety. We interpreted these findings by arguing that most people tend to preferentially elaborate positive rather than negative social stimuli that are important to the self and that this tendency may be reduced in high socially anxious individuals because of the negative meaning they tend to ascribe to positive social information.     

The normative development of child and adolescent problem behavior

The aim of this study was to identify normative developmental trajectories of parent-reported problems assessed with the Child Behavior Checklist (CBCL; T. M. Achenbach, 1991) in a representative sample of 2,076 children aged 4 to 18 years from the general population. The trajectories were determined by multilevel growth curve analyses on the CBCL syndromes in a Longitudinal multiple birth-cohort sample that was assessed 5 times with 2-year intervals. Most syndromes showed a linear increase or decrease with age or a curvilinear trajectory, except for thought problems. Trajectories for most syndromes differed for boys versus girls, except those for withdrawn, social problems, and thought problems. These normative developmental trajectories provide information against which developmental deviance in childhood and adolescence can be detected.     

Family predictors of antisocial behavior in adolescence

The goal of the present study was to examine the combined and unique ability of different aspects of family functioning to predict involvement in antisocial behavior in a large nonclinical (community) sample of adolescents. Distinction was made between global (e.g., family socioeconomic status), distal (dispositional characteristics of parents), contextual (family characteristics), and proximal (parent-child interaction) factors that operate within families. Results show that proximal factors were significant predictors of antisocial behavior, independent of their shared variance with other factors. Consistent with the hypothesized mediational model, the effects of distal and contextual factors appear to be mostly indirect: after their association with proximal factors was taken into account, these factors were no longer significantly related to antisocial behavior. The implications of these findings for planning of developmentally appropriate interventions for adolescents and their families are discussed.     

Cooperation,Knowledge, and Time: Alternating-time Temporal Epistemic Logic and its Applications

Branching-time temporal logics have proved to be an extraordinarily successful tool in the formal specification and verification of distributed systems. Much of their success stems from the tractability of the model checking problem for the branching time logic CTL, which has made it possible to implement tools that allow designers to automatically verify that systems satisfy requirements expressed in CTL. Recently, CTL was generalised by Alur, Henzinger, and Kupferman in a logic known as Alternating-time Temporal Logic (ATL). The key insight in ATL is that the path quantifiers of CTL could be replaced by cooperation modalities, of the form , where is a set of agents. The intended interpretation of an ATL formula is that the agents can cooperate to ensure that holds (equivalently, that have a winning strategy for ). In this paper, we extend ATL with knowledge modalities, of the kind made popular in the work of Fagin, Halpern, Moses, Vardi and colleagues. Combining these knowledge modalities with ATL, it becomes possible to express such properties as group can cooperate to bring about iff it is common knowledge in that . The resulting logic — Alternating-time Temporal Epistemic Logic (ATEL) — shares the tractability of model checking with its ATL parent, and is a succinct and expressive language for reasoning about game-like multiagent systems.