The many null distributions of person fit indices

This paper deals with the situation of an investigator who has collected the scores ofn persons to a set ofk dichotomous items, and wants to investigate whether the answers of all respondents are compatible with the one parameter logistic test model of Rasch. Contrary to the standard analysis of the Rasch model, where all persons are kept in the analysis and badly fittingitems may be removed, this paper studies the alternative model in which a small minority ofpersons has an answer strategy not described by the Rasch model. Such persons are called anomalous or aberrant. From the response vectors consisting ofk symbols each equal to 0 or 1, it is desired to classify each respondent as either anomalous or as conforming to the model. As this model is probabilistic, such a classification will possibly involve false positives and false negatives. Both for the Rasch model and for other item response models, the literature contains several proposals for a person fit index, which expresses for each individual the plausibility that his/her behavior follows the model. The present paper argues that such indices can only provide a satisfactory solution to the classification problem if their statistical distribution is known under the null hypothesis that all persons answer according to the model. This distribution, however, turns out to be rather different for different values of the person's latent trait value. This value will be called ability parameter, although our results are equally valid for Rasch scales measuring other attributes.As the true ability parameter is unknown, one can only use its estimate in order to obtain an estimated person fit value and an estimated null hypothesis distribution. The paper describes three specifications for the latter: assuming that the true ability equals its estimate, integrating across the ability distribution assumed for the population, and conditioning on the total score, which is in the Rasch model the sufficient statistic for the ability parameter.Classification rules for aberrance will be worked out for each of the three specifications. Depending on test length, item parameters and desired accuracy, they are based on the exact distribution, its Monte Carlo estimate and a new and promising approximation based on the moments of the person fit statistic. Results for the likelihood person fit statistic are given in detail, the methods could also be applied to other fit statistics. A comparison of the three specifications results in the recommendation to condition on the total score, as this avoids some problems of interpretation that affect the other two specifications.The authors express their gratitude to the reviewers and to many colleagues for comments on an earlier version.     

Integration and cue overlap in recognition failure of recallable words

A highly systematic relation between the conditional probability of recognition given recall and the overall recognition hit rate has been demonstrated in a wide variety of experiments. A function describing this relationship was developed by Tulving & Wiseman (1975). Exceptions to this function have, in retrospect, been interpreted in terms of (a) a low integration between cue and target items, or (b) a high cue overlap between the two tests involved: recognition and recall. The experiment reported was designed to evaluate the joint and the separate contributions from integration and cue overlap for obtaining conformity with and exception from the Tulving-Wiseman function. In line with the predictions made, the results showed that these two factors in combination can account for data that fit the function and for exceptions above the function. In relative terms, the contribution from integration was somewhat more pronounced than that from cue overlap.     

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.     

Falsification and Grünbaum's Duhemian theses

This paper is a detailed critical study of Adolf Grünbaum's work on the Duhemian thesis. I show that (a) Grünbaum's geometrical counterexample to the (D1) subthesis is unsuccessful, even with minimal claims made for what the counterexample is supposed to show, and (b) the (D2) subthesis is not a reasonable one (and cannot correctly be attributed to Duhem). The paper concludes with an argument about the relation between the Duhemian thesis, concerning component hypotheses of a scientific theory, and the view that it is impossible to falsify entire theories conclusively.     

Awakening from Descartes' nightmare: On the love of ambiguity in phenomenological approaches to education

This paper is an exploration of the Cartesian paradigms of clarity and univocity and how these inform contemporary educational theory and practice. Phenomenology is discussed as a way of disrupting Descartes' visions of clarity and distinctness as paradigms of knowledge and as a return of inquiry to life as it is actually lived. Analogical discourse is examined as a way of giving a voice to this sort of inquiry. Heidegger's notions of inquiry as obedience and thanksgiving are discussed.     

Converging operations on a basic level in event taxonomies

Research on object concepts has identified one level of abstraction as "basic" in cognition and communication. We investigated whether concepts for routine social events have a basic level by replicating the converging operations used to investigate object concepts. In Experiment 1, subjects were presented with event names from a taxonomy and were asked to list the actions comprising the event. Many more actions were listed at the middle than at the highest taxonomic level, without a further increase at the most specific level, paralleling the pattern of superordinate-, basic-, and subordinate-level object concepts. From these action lists, brief stories were composed for each event. In Experiment 2, subjects made pairwise similarity judgments on the stories. The mean similarity of events increased with specificity, as expected. But differentiation of categories (within-category similarity compared to between-category similarity) was highest for super-ordinates, contrary to results with object categories. In Experiment 3, subjects were fastest in recognizing actions as belonging to events named at the basic level. In Experiment 4, subjects predominantly chose basic-level terms to name stories. We conclude that event taxonomies do show basic-level structure, albeit a less sharply defined and less stable structure than in object taxonomies. The benefits and hazards of extending models of object concepts to other entities, such as social events, are discussed.     

Why Boys will be boys and girls will be girls: Understanding colloquial tautologies

What do tautological phrases such asBoys will be boys, A promise is a promise, or War is war mean and how are they understood? These phrases literally appear to be uninformative, yet speakers frequently use such expressions in conversation and listeners have little difficulty comprehending them. Understanding nominal tautologies requires that listeners/readers infer the speaker's attitude toward the noun phrase (e.g.,boys) mentioned in the sentence. The purpose of the present studies was to investigate the role of context, syntactic form, and lexical content in the interpretation of nominal tuatologies. Two studies are reported in which subjects rated the acceptability of different tautological constructions either alone (Experiment 1) or with supporting contextual information (Experiment 2). The results of these studies provide evidence that colloquial tautologies can be interpreted differently in different contexts, but that there are important regularities in the syntactic form and lexical content of these phrases which influence how they are understood. Our findings highlight the importance of speakers/listeners' stereotypical understanding of people, activities, and concrete objects in the use and understanding of different tautological expressions. The implications of this research for psycholinguistic theories of conversational inference and indirect language use are discussed.     

The role of compliance in hypnotic and nonhypnotic analgesia

We modified the standard procedure for administering finger pressure pain in order to assess the extent to which subjects biased their reports of pain reduction when exposed to compliance-inducing instructions. Experiment 1 used only highly hypnotizable subjects and found that compliance-induced reductions in reported pain were about half as large as the reported reductions produced by hypnotic analgesia suggestions. Experiment 2 used low as well as high hypnotizables and administered hypnotic or nonhypnotic analgesia instructions and compliance instructions to the same subjects on separate pain trials. Reported pain reductions produced by hypnotic and nonhypnotic analgesia suggestions and those produced by compliance instructions were substantially and significantly correlated. Furthermore, hypnotizability correlated with compliance-induced reported pain reductions as highly as it correlated with the reported reductions produced by hypnotic analgesia suggestions. Among high hypnotizables (but not low hypnotizables) compliant responding was predicted by social desirability. The findings of both studies indicate that compliance strongly influences the reports of hypnotic and nonhypnotic analgesia proffered by high hypnotizables. The role of compliance in the pain reductions reported by low hypnotizables is less clear-cut.     

Bilingual language processing after a lesion in the left thalamic and temporal regions. A case report with early childhood onset.

This case study concerns an 18-year-old bilingual girl who suffered a radiation lesion in the left (dominant) thalamic and temporal region when she was 4 years old. Language and memory assessment revealed deficits in auditory short-term memory, auditory word comprehension, nonword repetition, syntactic processing, word fluency, and confrontation naming tasks. Both languages (English and Dutch) were found to be affected in a similar manner, despite the fact that one language (English) was acquired before and the other (Dutch) after the period of lesion onset. Most of the deficits appear to be related to verbal (short-term) memory dysfunction. Several hypotheses of subcortical involvement in memory processes are discussed with reference to existing theories in this area.