Analyzing sequential categorical data: Individual variation in markov chains

Markov chains are probabilistic models for sequences of categorical events, with applications throughout scientific psychology. This paper provides a method for anlayzing data consisting of event sequences and covariate observations. It is assumed that each sequence is a Markov process characterized by a distinct transition probability matrix. The objective is to use the covariate data to explain differences between individuals in the transition probability matrices characterizing their sequential data. The elements of the transition probability matrices are written as functions of a vector of latent variables, with variation in the latent variables explained through a multivariate regression on the covariates. The regression is estimated using the EM algorithm, and requires the numerical calculation of a multivariate integral. An example using simulated cognitive developmental data is presented, which shows that the estimation of individual variation in the parameters of a probability model may have substantial theoretical importance, even when individual differences are not the focus of the investigator's concerns.Research contributing to this article was supported by B.R.S. Subgrant 5-35345 from the University of Virginia. I thank the DADA Group, Bill Fabricius, Don Hartmann, William Griffin, Jack McArdle, Ivo Molenaar, Ronald Schoenberg, Simon Tavaré, and several anonymous reviewers for their discussion of these points.     

Gender stereotypes and dimensions of effective leader behavior

Research has consistently found that effective leadership is perceived as characterized by traits similar to those associated with masculine gender roles. These perceptions would appear to be at odds with extensive research indicating that effective leadership requires consideration and structuring behaviors—behaviors that seem to represent both masculine and feminine styles. In two separate studies, the correspondence between gender stereotypes and dimensions of effective leadership were assessed. Results indicate that consideration behaviors are perceived to be feminine, while structuring behaviors are perceived to be masculine. Similarly, qualities that characterize the masculine gender role are perceived to be consistent with structuring, while qualities associated with the feminine gender roles are perceived to be consistent with consideration. It is suggested that an increased awareness of the androgynous nature of effective leadership behaviors might weaken the biases in favor of male leaders.     

Feigned insanity in nineteenth-century America: Tactics,trials, and truth

Feigned insanity in nineteenth-century America is appraised through a review of the medical and legal literature. The authors focus on the explanations for feigning, procedures used in uncovering feigning, and the role of feigning in the courtroom. This discussion of feigned insanity demonstrates the remarkable consistency of approach to this form of malingering over the past 200 years.     

An MMPI-based empirical model of malingering and deception

The empirically-based model of malingering and deception described by Rogers (1984b) was operationalized using MMPI and clinical interview data. Subjects (N = 159) were patients committed to an inpatient forensic hospital as ‘Incompetent to Stand Trial’ or ‘Not Guilty by Reason of Insanity’. Inter-rater reliability was acceptable for the 11 criteria used to define response styles. Each subject was categorized into one of five response style groups: ‘Reliable’, ‘Malingering’, ‘Defensive’, ‘Irrelevant’, or ‘Unclassifiable’. Factor analysis of the rating criteria yielded four factors, three of which are comparable to the assigned groups, providing some validation for the constructs underlying these groups.     

Reliability and Novelty: Information Gain in Multi-Level Selection Systems

Information about the environment is captured in human biological systems on a variety of interacting levels – in distributions of genes, linguistic particulars, concepts, methods, theories, preferences, and overt behaviors. I investigate some of the basic principles which govern such a hierarchy by constructing a comparatively simple three-level selection model of bee foraging preferences and behaviors. The information-theoretic notion of 'mutual information' is employed as a measure of efficiency in tracking a changing environment, and its appropriateness in epistemological applications is discussed at some length. In particular, information accumulated in mid-level preference distributions exhibits suggestive properties for the purposes of naturalistic epistemology. It also appears that the novelty of scientific objects and representations and the rapidity of scientific change relative to genetic change need present no obstacle to the use of such models in explanations of scientific progress and the reliability of scientific judgement.     

Children’s memory for counting-out rhymes: A cross-language comparison

In English, counting-out rhymes, such as “Eenie Meenie,” vary little over retellings. Recall is not rote but is sensitive to the structure of the genre. To test the generality of this finding, a sample of Romanian rhymes was collected. Although there was no overlap with the English rhymes, the corpus of rhymes collected had similar structure in terms of number of lines, repeating words, rhyme, alliteration, and the inclusion of nonsense words. Variation within rhymes preserved the poetic structure of the genre. The results suggest that verbatim recall can be schema driven if there is sufficient structure.     

Operate your own World-Wide Web server

Although many researchers wishing to use the World-Wide Web for academic purposes rely on centralized Web services, they should be aware that it is neither expensive nor difficult to operate their own server. Doing so provides research-related benefits such as complete control over their host name and documents provided, the guaranteed ability to execute common gateway interface and server-side include programs, immediate access to their collected data, and the ability to better control who participates in their experiments. This paper surveys Web-server software features likely to be of interest to psychologists and conceptually summarizes their operation and use. The basic steps required to set up a Web server on popular microcomputers are reviewed, and security issues concerning Web-server operation are discussed. An accompanying resource Web page can assist users in setting up their own servers.     

False Consensus,Stereotypic Cues,and the Perception of Integrative Potential in Negotiation1

We argue that negotiators' fixed-sum perceptions are caused by the same judgment process that creates false consensus. Bargainers' reliance on their own preferences as a cue to others' preferences leads them to anticipate a fixed-sum conflict. When presented with stereotypic cues, subjects in a negotiating experiment anticipated the variable-sum nature of the task and subsequently realized highly efficient settlements extremely quickly. Surprisingly, even when the party's preferences were unrepresentative of the stereotype, agreements were no less efficient than in the absence of the cue. The implications of these findings for bargaining research and practice are discussed.