Dual prism adaptation: calibration or alignment?

Dual adaptation to different amounts or directions of prismatic displacement, or both, can be acquired and maintained with little mutual interference. Associative recalibration of the regional task- or workspace, contingent on differentiation of distinguishing sensory information, can explain such adaptation. In contrast, nonassociative realignment restores dimensional mapping among spatial representations. Methods for measuring the separate contributions of those 2 kinds of prism adaptation are identified in the present article. On the basis of a critique of dual-adaptation studies, the authors suggest that recalibration can explain the data but that the method used in those experiments confounded realignment and might have obscured the effectiveness of dual-calibration training.     

The information for catching fly balls: judging and intercepting virtual balls in a CAVE

Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy--keeping constant the rate of change of the tangent of the elevation angle (d(tan(alpha))/dt)--leads a catcher to the right location at the right time to intercept a fly ball. Previous studies showed the ability to detect the information and the consistency of running patterns with the use of the strategy. However, only direct manipulation of information can show its use. Participants were asked to intercept virtual balls in a Cave Automated Virtual Environment (CAVE) or to judge whether balls would pass behind or in front of them. Catchers in the CAVE successfully intercepted virtual balls with their forehead. Furthermore, the timing of judgments was related to the patterns of changing d(tan(alpha))/dt. The advantages and disadvantages of a CAVE as a tool for studying interceptive action are discussed.     

Geometrics and dynamics of a rod determine how it is used for reaching

Displacing an object with a hand-held rod provided a simple paradigm for studying tool use. The authors asked how reaching was affected by manipulations of rod properties. Adults held a rod (length =.10 to 1.5 m), with its tip in the air; walked toward an object on a table; chose a place to stop; and displaced the object with the rod's tip. In 3 experiments (Ns = 9, 22, and 17 participants), the authors manipulated rod length, mass, and mass distribution to determine whether and how geometric and dynamic properties affected the chosen distance and the posture. Both the chosen stopping distance and the postures were well accommodated to rod characteristics. Postural adaptations took place only in the arm, which was organized as a synergy. Predictably, rod length explained most of the variance, but small and reliable differences in both distance and posture depended on mass and mass distribution. The chosen distance anticipated not only rod length but also the upcoming posture needed to control the rod.     

Boredom proneness and sleep disorders as predictors of adult attention deficit scores

This study examined the extent to which boredom proneness and sleep disturbances were related to attention deficit scores in college-aged adults. In a sample of 148 college students, Attention scores on the Adult Behavior Checklist were best predicted by Boredom Proneness (BP) subscale scores, which assess one's inability to maintain internal stimulation and feelings of constraint, and scores on the Epworth Daytime Sleepiness Scale and Athens Insomnia Scale (R2 = .57). Hyperactivity scores were best predicted by the BP subscales, which assess one's need for a stimulating environment, the perception of time passing slowly, and feelings of constraint, and the Epworth Scale (R2 = .51). The findings contribute to the understanding of the symptomatology of attention deficit in adults and provide further evidence of the validity of this measure.     

Visual perspective taking for avatars in a Simon task

In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met.     

Pragmatic Assessment and Therapy for Persons with Brain Damage: What Have Clinicians Gleaned in Two Decades?

Pragmatic competence comprises a number of interrelated skills which manifest in real-time in a range of adaptive behaviors and which are driven by underlying cognitive processes that appear to be variably compromised in brain damage. Differential neurological profiles reflect different pragmatic outcomes. The essence of pragmatic assessment and therapy for clinicians is therefore to capture accurately, measure, and, where possible, enhance the ability of the individual to adapt to a changing communicative environment. Assessment measures differ along a number of dimensions. A distinction is drawn between testing and assessment and the argument proposed that for clinical purposes, it is helpful to keep the notions of functional and pragmatic distinct.     

Knowledge level learning and the power law: A soar model of skill acquisition in scheduling

Zusammenfassung. Das hier vorgestellte Modell lernt graduell, Planungsaufgaben aus der Klasse der Maschinenbelegungsprobleme (job-shop-scheduling problems) zu lösen. Mit Hilfe des Chunking-Mechanismus von Soar wird episodisches Wissen über die Belegungsreihenfolge von Aufträgen auf Maschinen memoriert. Bei der Entwicklung des Modells wurden zahlreiche qualitative (z. B. Transfereffekte) und quantitative Befunde (z. B. Bearbeitungszeiten) aus einer früheren empirischen Untersuchung berücksichtigt. In einer Validierungsstudie wurden dieselben Aufgaben von 14 Probanden und dem Modell bearbeitet. Die Passung von Simulationsdaten und empirischen Ergebnissen fiel insgesamt gut aus. Allerdings löst das Modell die Aufgaben schneller und zeigt auch einen etwas besseren Lernverlauf als die Probanden. Das Modell liefert eine Erklärung für das Rauschen, das typischerweise bei Bearbeitungszeiten zu beobachten ist: es handelt sich um erworbenes Wissen, das mehr oder weniger gut und auch unterschiedlich häufig auf neue Situationen übertragen wird. Der Lernverlauf der Probanden entspricht nur für aggregierte Daten einer Potenzfunktion (power law). Der vorgestellte Mechanismus zeigt, wie ein symbolisches Modell der Informationsverarbeitung graduelle Verhaltensänderungen generiert und wie der offensichtliche Erwerb allgemeiner Prozeduren ohne explizites Lernen von deklarativen Regeln erfolgen kann. Es wird nahegelegt, daß es sich hier um die Modellierung einer Form impliziten Lernens handelt. Summary. The model presented here gradually learns how to perform a job-shop scheduling task. It uses Soar's chunking mechanism to acquire episodic memories about the order to schedule jobs. The model was based on many qualitative (e.g., transfer effects) and quantitative (e.g., solution time) regularities found in previously collected data. The model was tested with new data where scheduling tasks were given to the model and to 14 subjects. The model generally fit these data with the restrictions that the model performs the task (in simulated time) faster than the subjects, and its performance improves somewhat more quickly than the subjects' performance. The model provides an explanation of the noise typically found in problem solving times - it is the result of learning actual pieces of knowledge that transfer more or less to new situations but rarely by an average amount. Only when the data are averaged (i.e., over subjects) does the smooth power law appear. This mechanism demonstrates how symbolic models can exhibit a gradual change in behavior and how the apparent acquisition of general procedures can be performed without resorting to explicit declarative rule generation. We suggest that this may represent a type of implicit learning.     

The puzzle of language evolution

Linguistics must again concentrate on the evolutionary nature of language, so that language models are more realistic with respect to human natural languages and have a greater explanatory force. Multi-agent systems are proposed as a possible route to develop such evolutionary models and an example is given of a concrete experiment in the origins and evolution of word-meaning based on a multi-agent approach.