Delay reduction: current status.

Delay-reduction theory states that the effectiveness of a stimulus as a conditioned reinforcer may be predicted most accurately by the reduction in time to primary reinforcement correlated with its onset. We review support for the theory and then discuss two new types of experiments that assess it. One compares models of choice in situations wherein the less preferred outcome is made more accessible; the other investigates whether frequency of conditioned reinforcement affects choice beyond the effect exerted by frequency of primary reinforcement.     

Timeout from concurrent schedules.

Response-contingent timeouts of equal duration and frequency were added to both alternatives of unequal concurrent schedules of reinforcement. For each of 4 pigeons in Experiment 1, relative response rates generally became less extreme as the frequency of timeout increased. In Experiment 2, relative response rates consistently approached indifference as the duration of timeout was increased. Variation in time allocation was less consistent in both experiments. Absolute response rates did not vary with the timeout contingency in either experiment. In a third experiment, neither measure of choice varied systematically when the duration of a postreinforcement blackout was varied. In contrast to the present results, preference has been shown to vary directly with the parameters of shock delivery in related procedures. The pattern of results in the first two experiments follows that obtained with other manipulations of the overall rate of reinforcement in concurrent schedules. The results of the third experiment suggest that an intertrial interval following reinforcement is not a critical feature of the overall rate of reinforcement.     

Normal values for Type A behaviour patterns in Danish men and women and in potential high-risk groups

The Jenkins Activity Survey (JAS) was administered to a normal population of randomly selected Danish adults, to patients consulting a cardiologist, and to physicians in order to compare those groups in terms of their coronary-prone (Type A) behaviour patterns. The standard procedure of rating the JAS was used in order to obtain scores for each of the four subscales: Type A (time urgency and ambitiousness), Factor S (speed and impatience) Factor H (hard-driving and competitive) and Factor J (job involvement). Gender differences were observed in the normal population for each of the four subscale scores, and age-related differences were obtained for Factor J. Elevated scores for Factor S were obtained by physicians and by people in the population who had a cardiovascular disorder. Physicians had also elevated scores for Factor J, whereas their Factor H scores tended to be reduced. No reliable differences in JAS subscale scores were observed between four groups of heart patients (i.e. angina pectoris, arterial hypertension, atrial fibrillation and atherosclerosis), although there was a tendency for Factor J to be elevated in atherosclerosis. The findings provide normal values for JAS scores in Danish men and women, and suggest that some facets of coronary-prone behaviour may be enhanced in Danish high-risk groups.     

On the sampling theory roundations of item response theory models

Item response theory (IT) models are now in common use for the analysis of dichotomous item responses. This paper examines the sampling theory foundations for statistical inference in these models. The discussion includes: some history on the stochastic subject versus the random sampling interpretations of the probability in IRT models; the relationship between three versions of maximum likelihood estimation for IRT models; estimating versus estimating -predictors; IRT models and loglinear models; the identifiability of IRT models; and the role of robustness and Bayesian statistics from the sampling theory perspective.A presidential address can serve many different functions. This one is a report of investigations I started at least ten years ago to understand what IRT was all about. It is a decidedly one-sided view, but I hope it stimulates controversy and further research. I have profited from discussions of this material with many people including: Brian Junker, Charles Lewis, Nicholas Longford, Robert Mislevy, Ivo Molenaar, Donald Rock, Donald Rubin, Lynne Steinberg, Martha Stocking, William Stout, Dorothy Thayer, David Thissen, Wim van der Linden, Howard Wainer, and Marilyn Wingersky. Of course, none of them is responsible for any errors or misstatements in this paper. The research was supported in part by the Cognitive Science Program, Office of Naval Research under Contract No. Nooo14-87-K-0730 and by the Program Statistics Research Project of Educational Testing Service.     

Continuous and discrete latent structure models for item response data

Relations are examined between latent trait and latent class models for item response data. Conditions are given for the two-latent class and two-parameter normal ogive models to agree, and relations between their item parameters are presented. Generalizationss are then made to continuous models with more than one latent trait and discrete models with more than two latent classes, and methods are presented for relating latent class models to factor models for dichotomized variables. Results are illustrated using data from the Law School Admission Test, previously analyzed by several authors.     

The use of the occupational stress indicator (OSI) in factory workers in China

The purpose of the study was to investigate occupational stress among Chinese factory workers (N=342), from three cities of South East China, using the shortened version of the Occupational Stress Indicator (OSI)-2. The results showed that the reliabilities and predictive validity of the OSI-2 subscales and other subscales used for the study were reasonably high. Quite a high percentage of workers perceived high work pressure. The main sources of stress were intrinsic to the job; and the coping strategies that were most frequently used to tackle stress were “control” methods. In addition, “satisfaction on environmental condition” seemed to be a common predictor for job satisfaction, and mental and physical well-being. The logical relationships between job satisfaction, mental well-being and physical well-being in Chinese workers have provided support to the findings obtained in Western countries.     

Exploring the set-theoretical structure of objects by additive trees

Arrangements of feature sets that have been proposed to represent qualitative and quantitative variation among objects are shown to generate identical sets of set-symmetric distances. The set-symmetric distances for these feature arrangements can be represented by path lengths in an additive linear tree. Imperfect versions of these feature arrangements are proposed, which also are indistinguishable by the set-symmetric distance model. The distances for the imperfect versions can be represented by path lengths in an additive imperfectly linear tree. When dissimilarities are defined by the more general contrast model and a constant may be added to proximity data, then for both the perfect and imperfect arrangements an additive tree analysis obtains a perfect fit with an imperfectly linear tree. However, in the case of the contrast model also the distinction between the perfect and imperfect arrangements disappears in that also for the perfect arrangements the resulting tree need no longer be linear.The author is grateful to Mathieu Koppen for detailed comments on an earlier version of this article.     

计算机支持下协同工作的心理学研究

计算机支持下协同工作（ｃｏｍｐｕｔｅｒｓｕｐｐｏｒｔｅｄｃｏｏｐｅｒａｔｉｖｅｗｏｒｋ,简称ＣＳＣＷ）是计算机科学和认知科学的新兴交叉研究领域,主要研究在高技术支持下的群体协作。ＣＳＣＷ中蕴含着大量的心理学研究问题。心理学家需要更好地理解群体协作的性质以评估新技术是否与群体协作相适应,其研究成果会有助于理解如何构建技术和哪些技术可能成功。本文首先从分析ＣＳＣＷ的领域维度入手,然后讨论与之相关的一些重要的心理学研究问题,最后简要介绍国外在该领域进行的研究工作