Writing errors by normal subjects

Writing is a complex process requiring visual memory, attention, phonological and semantic operations, and motor performance. For that reason, it can easily be disturbed by interfering with attention, memory, by interfering subvocalization, and so on. With 16 female third-year students (23.4 +/- 0.8 yr.) from the University of Trieste, we investigated the production of errors in three experimental conditions (control, articulatory suppression, and tapping). In the articulatory suppression condition, the participants produced significantly more linguistic impairments (such as agrammatism, unrelated substitutions, sentence omissions, and semantically deviant sentences), which are similar to linguistic impairments found in aphasia. On the tapping condition there were more perseverations, deletions, and substitutions of both letters and words. These data suggest that writing is not an automatic skill. Only after many years of experience and practice of processing information (through cortical to subcortical channels) can writing be considered an automatic skill. Limited experimental conditions can disrupt the writing system of normal subjects, probably interfering with the cortical to subcortical loops, and link normality to pathology.     

Modality-specific effects in inhibitory mechanisms: the interaction of peripheral and central components in working memory

Working memory is a complex system assumed to encompass both storage and processing components. At the same time, several authors have suggested the existence of separate peripheral modality-specific subsystems, in particular a verbal and a visuo-spatial mechanism. In the present research, we explored the hypothesis that modality-specific mechanisms may also operate in the central processing component. Inhibitory control has traditionally been considered as a typical function of the central executive, devoted to selecting, processing, and eliminating irrelevant information. We designed verbal and visuo-spatial tasks involving similar procedures and comparable levels of inhibitory control. Results indicate that accuracy profiles are similar in the two conditions; however, the patterns of data measuring inhibitory control, i.e., percentage of intrusion errors, are opposite in the case of verbal (intrusions decreased in more complex trials) and visuo-spatial (intrusions increased in more complex trials) material. These data are consistent with theoretical models of working memory suggesting that modality-specific effects emerge even in central processes and that both material-dependent and process-dependent features must be considered in working memory tasks.     

Antigravity hills are visual illusions

Antigravity hills, also known as spook hills or magnetic hills, are natural places where cars put into neutral are seen to move uphill on a slightly sloping road, apparently defying the law of gravity. We show that these effects, popularly attributed to gravitational anomalies, are in fact visual illusions. We re-created all the known types of antigravity spots in our laboratory using tabletop models; the number of visible stretches of road, their slant, and the height of the visible horizon were systematically varied in four experiments. We conclude that antigravity-hill effects follow from a misperception of the eye level relative to gravity, caused by the presence of either contextual inclines or a false horizon line.     

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.     

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.     

Moral principles as moral dispositions

What are moral principles? In particular, what are moral principles of the sort that (if they exist) ground moral obligations or—at the very least—particular moral truths? I argue that we can fruitfully conceive of such principles as real, irreducibly dispositional properties of individual persons (agents and patients) that are responsible for and thereby explain the moral properties of (e.g.) agents and actions. Such moral dispositions (or moral powers) are apt to be the metaphysical grounds of moral obligations and of particular truths about what is morally permissible, impermissible, etc. Moreover, they can do other things that moral principles are supposed to do: explain the phenomena “falling within their scope,” support counterfactuals, and ground moral necessities, “necessary connections” between obligating reasons and obligations. And they are apt to be the truthmakers for moral laws, or “lawlike” moral generalizations.     

A cleansing fire: Moral outrage alleviates guilt and buffers threats to one’s moral identity

Why do people express moral outrage? While this sentiment often stems from a perceived violation of some moral principle, we test the counter-intuitive possibility that moral outrage at third-party transgressions is sometimes a means of reducing guilt over one’s own moral failings and restoring a moral identity. We tested this guilt-driven account of outrage in five studies examining outrage at corporate labor exploitation and environmental destruction. Study 1 showed that personal guilt uniquely predicted moral outrage at corporate harm-doing and support for retributive punishment. Ingroup (vs. outgroup) wrongdoing elicited outrage at corporations through increased guilt, while the opportunity to express outrage reduced guilt (Study 2) and restored perceived personal morality (Study 3). Study 4 tested whether effects were due merely to downward social comparison and Study 5 showed that guilt-driven outrage was attenuated by an affirmation of moral identity in an unrelated context.