Self-organization of alcohol-related attitudes and beliefs in a campus housing complex: an initial investigation.

The self-organization of college students' alcohol-related attitudes and their beliefs about other students' attitudes were assessed within a campus housing complex. Pluralistic ignorance was widespread, in that, compared with their own self-ratings, students rated their friends and the "typical" student as being more in favor of alcohol and more lax in the number of drinks per hour that were acceptable and the number of drinks that were acceptable before driving. They also perceived typical students as more risky than their friends. Dynamic social impact theory was also supported, as students' dormitory building and floor of residence reliably predicted both their personal drinking attitudes and their beliefs about the drinking attitudes of other students.     

New mothers and their babies: attachment in the face of maternal life-threatening illness

Life-threatening illness in the mothers of babies or young children is rare. Its impact is discussed in this paper, which focuses on attachment theory as a foundation for work in this area. A single case study is used to illustrate the potential conflicts and dilemmas for professionals caring for babies and their families in this situation.     

Studying Sexual Harassment in the Laboratory: Are Egalitarian Women at Higher Risk?

A laboratory experiment is reported in whichmale participants in Northern Italy (N = 120 universitystudents) were given the opportunity to sendpornographic material to a female interaction partner(“computer harassmentparadigm”). The allegedgender-role orientation of the female (traditional vs.egalitarian) and the construal of the interaction aseither intergroup or interpersonal were variedsystematically. Results show that participants molest femaleinteraction partners more when they express egalitarianrather than traditional gender-role attitudes; this isparticularly true for males with a high propensity to harass (high scores on likelihood of sexualharassment scale, Pryor, 1987), with sexist attitudes,with a strong identification as “males,” andfor low self-monitors. Also, males with a highpropensity to harass were more likely to harass theirinteraction partner when they perceived the situation asa male-female inter-group setting (rather than asinterpersonal). Results are interpreted as supporting a social identity account ofmisogyny.     

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.     

Bayesian estimation and testing of structural equation models

The Gibbs sampler can be used to obtain samples of arbitrary size from the posterior distribution over the parameters of a structural equation model (SEM) given covariance data and a prior distribution over the parameters. Point estimates, standard deviations and interval estimates for the parameters can be computed from these samples. If the prior distribution over the parameters is uninformative, the posterior is proportional to the likelihood, and asymptotically the inferences based on the Gibbs sample are the same as those based on the maximum likelihood solution, for example, output from LISREL or EQS. In small samples, however, the likelihood surface is not Gaussian and in some cases contains local maxima. Nevertheless, the Gibbs sample comes from the correct posterior distribution over the parameters regardless of the sample size and the shape of the likelihood surface. With an informative prior distribution over the parameters, the posterior can be used to make inferences about the parameters underidentified models, as we illustrate on a simple errors-in-variables model.We thank David Spiegelhalter for suggesting applying the Gibbs sampler to structural equation models to the first author at a 1994 workshop in Wiesbaden. We thank Ulf Böckenholt, Chris Meek, Marijtje van Duijn, Clark Glymour, Ivo Molenaar, Steve Klepper, Thomas Richardson, Teddy Seidenfeld, and Tom Snijders for helpful discussions, mathematical advice, and critiques of earlier drafts of this paper.     

The Identity Status Approach: In Need of Fundamental Revision and Qualitative Change

This article is a response to the commentaries of Waterman (this issue) and Berzonsky and Adams (this issue) on my review of the identity status field (van Hoof, this issue). The commentaries illustrate that the identity status researchers attribute different meanings to the identity statuses and identity status research; while Waterman finds it difficult to recognize the field in my review, Berzonsky and Adams agree with several of my conclusions. The two commentaries represent two pillars on which the status approach rests. The difference between the review and the commentaries is that the first includes both pillars, whereas each commentary consists primarily of a selective presentation of assumptions and data. This response focuses on two main points of the commentaries: (a) are the statuses sufficiently validated? and (b) to what extent are they suitable for testing developmental identity hypotheses? Using specific examples I show that the line of reasoning in the commentaries and the data proposed in support of these arguments in fact often support the conclusions of my review, for I demonstrate that the statuses are insufficiently validated and that the statuses are unsuitable for measuring identity development. These conclusions call for a fundamental revision of the identity status approach and a qualitative change in identity theory and research. Finally, the alternative approaches presented by Berzonsky and Adams are evaluated with respect to their contribution to an indispensable qualitative change in the identity status field.