A general latent assignment approach for modeling psychological contaminants

Data from psychological experiments are rife with ‘contaminants’, which can generally be defined as data generated by psychological processes different from those intended as the object of study. Contaminant data can interfere with the testing of substantive psychological models and their parameters, so it is important to have methods for their identification and removal. After noting that current practices in cognitive modeling for dealing with contaminants are not completely satisfactory, we argue for a general latent mixture approach to the problem. We demonstrate the tractability and effectiveness of the approach concretely, through a series of four applications. These applications involve a simple choice problem, a diffusion model of a response time and accuracy in decision-making, a hierarchical signal detection model of recognition memory, and a reinforcement learning model of decision-making on bandit problems. We conclude that developing models of contaminant processes requires the same sort of creative effort that is needed to model substantive psychological processes, but that it is a necessary endeavour that can be coherently and usefully pursued within the latent mixture modeling approach.     

Temporal context in speech processing and attentional stream selection: a behavioral and neural perspective

The human capacity for processing speech is remarkable, especially given that information in speech unfolds over multiple time scales concurrently. Similarly notable is our ability to filter out of extraneous sounds and focus our attention on one conversation, epitomized by the ‘Cocktail Party’ effect. Yet, the neural mechanisms underlying on-line speech decoding and attentional stream selection are not well understood. We review findings from behavioral and neurophysiological investigations that underscore the importance of the temporal structure of speech for achieving these perceptual feats. We discuss the hypothesis that entrainment of ambient neuronal oscillations to speech’s temporal structure, across multiple time-scales, serves to facilitate its decoding and underlies the selection of an attended speech stream over other competing input. In this regard, speech decoding and attentional stream selection are examples of ‘Active Sensing’, emphasizing an interaction between proactive and predictive top-down modulation of neuronal dynamics and bottom-up sensory input.     

The tune in-and-out model: A random walk and its application to a presidential election survey

The stochastic model for the evolution of preferences proposed by Falmagne, Regenwetter, and Grofman [1997. Journal of Mathematical Psychology, 41, 129-143] and tested by Regenwetter, Falmagne, and Grofman [1999. Psychological Review, 106, 362-384], as well as the alternative Thurstonian model of Böckenholt [Falmagne, J.-C., Regenwetter, M., & Grofman, B. (1997). A stochastic model for the evolution of preferences. In A. A. J. Marley (Ed.), Choice, decision and measurement: Essays in honor of R. Duncan Luce (pp. 113-131). Mahwah, NJ: Lawrence Erlbaum.], gave a good statistical account of attitudinal panel data from the 1992 US presidential election. We show, however, that both models have the defect of underestimating the number of respondents who did not change their order of preference for the candidates across different polls. We present a generalization of Falmagne et al.'s model based on the idea that some individuals may become momentarily impervious to all matters related to the campaign and ‘tune out.’ This behavior could be triggered by some personal reason or by some external event related to the campaign. Like the original model, the resulting model is a random walk, but on an augmented set of states. A respondent in a ‘live’ state behaves as in the previous model, except when receiving a ‘tune-out’ token, which effectively freezes the respondent's preference state until it is reversed by a ‘tune-in’ token. We describe and successfully test the new model on the same 1992 National Election Study panel data as those used by Böckenholt (2002) and Regenwetter et al. (1999).     

Signal detection theory with item effects

Applications of signal detection theory (SDT) often involve presentations of different items on each trial, such as slides in a medical imaging study or words in a memory study. If factors particular to the items themselves, apart from being a signal or noise, affect observers’ responses, then ‘item effects’ are present. One way to model these effects is to use a latent continuous variable as an item ‘factor’, such as item ‘difficulty’. Details of SDT models with item effects are clarified via derivations of their implied conditional means, variances, and covariances. Intra-item correlations are defined and suggested as measures of the magnitude of item effects. The SDT-item models are simple random coefficient models and can be fit with standard software. More general models, such as item models with mixing and/or with random observer effects, are also considered.     

Bayesian nonparametric model selection and model testing

This article examines a Bayesian nonparametric approach to model selection and model testing, which is based on concepts from Bayesian decision theory and information theory. The approach can be used to evaluate the predictive-utility of any model that is either probabilistic or deterministic, with that model analyzed under either the Bayesian or classical-frequentist approach to statistical inference. Conditional on an observed set of data, generated from some unknown true sampling density, the approach identifies the “best” model as the one that predicts a sampling density that explains the most information about the true density. Furthermore, in the approach, the decision is to reject a model when it does not explain enough information about the true density (according to a straightforward calibration of the Kullback-Leibler divergence measure). The posterior estimate of the true density is based on a Bayesian nonparametric prior that can give positive support to the entire space of sampling densities (defined on some sample space). This article also discusses the theoretical and practical advantages of the Bayesian nonparametric approach over all other types of model selection procedures, and over any model testing procedure that depends on interpreting a p-value. Finally, the Bayesian nonparametric approach is illustrated on four real data sets, in the comparison and testing of order-constrained models, cognitive models, models of choice-behavior, and a test of a general psychometric model.     

The influence of synesthesia on eye movements: no synesthetic pop-out in an oculomotor target selection task

Recent research on grapheme-colour synesthesia has focused on whether visual attention is necessary to induce a synesthetic percept. The current study investigated the influence of synesthesia on overt visual attention during an oculomotor target selection task. Chromatic and achromatic stimuli were presented with one target among distractors (e.g. a ‘2’ (target) among multiple ‘5’s (distractors)). Participants executed an eye movement to the target. Synesthetes and controls showed a comparable target selection performance across conditions and a ‘pop-out effect’ was only seen in the chromatic condition. As a pop-out effect was absent for the synesthetes in the achromatic condition, a synesthetic element appears not to elicit a synesthetic colour, even when it is the target. The synesthetic percepts are not pre-attentively available to distinguish the synesthetic target from synesthetic distractors when elements are presented in the periphery. Synesthesia appears to require full recognition to bind form and colour.     

An economic perspective on the Reinforcement Sensitivity Theory of personality

Reinforcement Sensitivity Theory postulates personality factors of ‘reward sensitivity’ and ‘punishment sensitivity’ linked to neural systems that control approach and avoidance, respectively. In contrast, behavioural economics distinguishes gain (‘reward’) and loss (‘punishment’) valuation systems that are orthogonal to approach/avoidance behaviour. We combined gain and loss with both their presentation and omission and found evidence for separate gain valuation, loss valuation, approach, and avoidance systems. This suggests that it is possible to integrate valuation/input and behaviour/output views of ‘reward’ and ‘punishment’ in a way that may be of use to both personality theory and economics and so forge closer links between these two major perspectives on decision-making and behaviour.     

Modulating younger and older adults’ performance in ignoring pictorial information during a word matching task

Using both behavioural and event-related potential (ERP) data, the current study sought to examine the neurophysiological underpinnings for the effect of distracting pictorial information on semantic word matching performance in younger and older adults. This was tested in the context of semantic relations between task-relevant word pairs, a task-irrelevant picture and the resultant N400 differences in ERP. Younger and older adults were shown a context word superimposed on a to-be-ignored picture, followed by a test word. Their task was to determine whether the prime and test words were semantically related. The to-be-ignored pictures were interfering (for ‘No’ trials), facilitating (for ‘Yes’ trials), or neutral (for both ‘Yes’ and ‘No’ trials) to the expected responses. The interfering and facilitatory effects of to-be-ignored pictures were assessed under more automatic and more controlled conditions by manipulating the context–test interstimulus-interval (ISI) as 50 ms and 1000 ms, respectively. The analysis of the N400 at centro-parietal sites during test word display revealed similar N400 amplitudes for the ‘No’ response trials at the two ISIs, suggesting that younger and older adults showed an equivalent effect from interfering pictures. In contrast, younger adults showed greater reductions in the N400, as compared to older adults, for ‘Yes’ trials indicating differential effects in facilitation from to-be-ignored pictorial information, but only in the long ISI condition. The data are discussed in terms of age differences in resource demanding strategy use during a semantic word matching task, specifically during controlled retrieval.     

Detection of suppressed involvement with information through a forced number-guessing technique

Subjects were instructed to learn a ‘crime’ profile consisting of numerical information, such as the number of the house where the crime was committed, the age of the victim, etc. They were then told not to reveal the information during an interrogation that followed. All the Ss underwent an interrogation in which they were asked to guess the ‘crime’ profile. It was found that it was possible to detect efficiently involvement with the suppressed profile through the use of correlations between the guessed profiles and the ‘crime’ profile as a decision dimension.     

A new approach to the formulation and testing of learning models

It is argued that current attempts to model human learning behavior commonly fail on one of two counts: either the model assumptions are artificially restricted so as to permit the application of mathematical techniques in deriving their consequences, or else the required complex assumptions are imbedded in computer programs whose technical details obscure the theoretical content of the model. The first failing is characteristic of so-called mathematical models of learning, while the second is characteristic of computer simulation models. An approach to model building which avoids both these failings is presented under the title of a black-box theory of learning. This method permits the statement of assumptions of any desired complexity in a language which clearly exhibits their theoretical content.Section II of the paper is devoted to the problem of testing and comparing alternative learning theories. The policy advocated is to abandon attempts at hypothesis testing. It is argued that, in general, we not only lack sufficient data and sufficiently powerful techniques to test hypotheses, but that the truth of a model is not really the issue of basic interest. A given model may be true in the sense that on the basis of available evidence we cannot statistically reject it, but not interesting in the sense that it provides little information about the processes underlying behavior. Rather, we should accept or reject models on the basis of how much information they provide about the way in which subjects respond to environmental structure. This attitude toward model testing is made precise by introducing a formal measure of the information content of a model. Finally, it is argued that the statistical concept of degrees-of-freedom is misleading when used in the context of model testing and should be replaced by a measure of the information absorbed from the data in estimating parameters.I would like to express my indebtedness to Ernest W. Adams and Julian Feldman for their guidance and encouragement of the research reported here.Much of the research reported here was conducted at the University of California, Berkeley, and incorporated in a Ph.D. dissertation in Logic and the Methodology of Science [15]. The research was supported in part by the Computer Institute for Social Science Research, Michigan State University.     

Western esotericism: Towards an integrative model of interpretation

Despite the fact that during the last fifteen years we have witnessed the emergence of a research field of ‘Western esotericism’, scholars are still far from agreeing on definitions of ‘esotericism’. For an academic ‘field’, however, that wants to establish international networks and to bring together scholars from various research areas and disciplines, it is highly desirable to provide an interpretational framework in which these different studies find their place. The main argument of this article is that such common ground can be found only when esotericism is seen not as a selection of historical ‘currents’, however defined, but as a structural element of Western culture. After reviewing the most influential approaches to Western esotericism, this article identifies two dimensions of an esoteric discourse: claims of higher knowledge and ways of accessing this ‘truth’. To these dimensions can be added certain world views that are typically involved in there discourses. The interpretative model proposed here aims at critically addressing basic aspects of Western self-understanding including the rhetorics of rationality, science, enlightenment, progress and absolute truth. It postulates that conflicts of religious world views, identities and forms of knowledge lie at the heart of Western cultural history.