The mixed model for multivariate repeated measures: validity conditions and an approximate test

Repeated measures on multivariate responses can be analyzed according to either of two models: a doubly multivariate model (DMM) or a multivariate mixed model (MMM). This paper reviews both models and gives three new results concerning the MMM. The first result is, primarily, of theoretical interest; the second and third have implications for practice. First, it is shown that, given multivariate normality, a condition called multivariate sphericity of the covariance matrix is both necessary and sufficient for the validity of the MMM analysis. To test for departure from multivariate sphericity, the likelihood ratio test can be employed. The second result is an approximation to the null distribution of the likelihood ratio test statistic, useful for moderate sample sizes. Third, for situations satisfying multivariate normality, but not multivariate sphericity, a multivariate correction factor is derived. The correction factor generalizes Box's and can be used to construct an adjusted MMM test.I am grateful to an anonymous referee for carefully attending to the mathematical details of this paper.     

Intolerance of uncertainty and difficulties in emotion regulation: Proposal for an integrative model of generalized anxiety disorder

Introduction

The Intolerance of Uncertainty Model (IUM) is a well-tested model of generalized anxiety disorder (GAD).

Knowing full well: the normativity of beliefs as performances

Belief is considered a kind of performance, which attains one level of success if it is true (or accurate), a second level if competent (or adroit), and a third if true because competent (or apt). Knowledge on one level (the animal level) is apt belief. The epistemic normativity constitutive of such knowledge is thus a kind of performance normativity. A problem is posed for this account by the fact that suspension of belief seems to fall under the same sort of epistemic normativity as does belief itself, yet to suspend is of course precisely not to perform, certainly not with the aim of truth. The paper takes up this problem, and proposes a solution that distinguishes levels of performance norrmativity, including a first order where execution competence is in play, and a second order where the performer must assess the risks attendant on issuing a first-order performance. This imports a level of reflective knowledge that ascends above the animal level.

Sensori-motor integration during stance: Time adaptation of control mechanisms on adding or removing vision

Sudden addition or removal of visual information can be particularly critical to balance control. The promptness of adaptation of stance control mechanisms is quantified by the latency at which body oscillation and postural muscle activity vary after a shift in visual condition. In the present study, volunteers stood on a force platform with feet parallel or in tandem. Shifts in visual condition were produced by electronic spectacles. Ground reaction force (center of foot pressure, CoP) and EMG of leg postural muscles were acquired, and latency of CoP and EMG changes estimated by t-tests on the averaged traces. Time-to-reach steady-state was estimated by means of an exponential model. On allowing or occluding vision, decrements and increments in CoP position and oscillation occurred within about 2 s. These were preceded by changes in muscle activity, regardless of visual-shift direction, foot position or front or rear leg in tandem. These time intervals were longer than simple reaction-time responses. The time course of recovery to steady-state was about 3 s, shorter for oscillation than position. The capacity of modifying balance control at very short intervals both during quiet standing and under more critical balance conditions speaks in favor of a necessary coupling between vision, postural reference, and postural muscle activity, and of the swiftness of this sensory reweighing process.     

A model for detection and recognition with signal uncertainty

A model for signal detectability suggested by Luce is extended to situations in which the observer is uncertain of some important characteristic of the signal, such as frequency. By making a single assumption concerning the observer's covert response behavior, two solutions are obtained corresponding to qualitatively different behavior. Decrements in detectability and in recognition with uncertainty are shown to be particular functions of discriminability and detectability of the stimuli in other situations. Relevant experimental data are considered.This work was supported by grant NSF-G5544 from the National Science Foundation. The author is indebted to R. Duncan Luce for critical discussion of the content and helpful suggestions concerning the form of this paper. Useful comments have been made by David M. Green, Francis W. Irwin, Roger M. Shepard, and W. P. Tanner, Jr.     

Evidence for the role of self-priming in epistemic action: expertise and the effective use of memory

Epistemic actions are physical actions people take to simplify internal problem solving rather than to move closer to an external goal. When playing the video game Tetris, for instance, experts routinely rotate falling shapes more than is strictly needed to place the shapes. Maglio and Kirsh [Kirsh, D., & Maglio, P. (1994). On distinguishing epistemic from pragmatic action. Cognitive Science, 18, 513-549; Maglio, P. P. (1995). The computational basis of interactive skill. PhD thesis, University of California, San Diego] proposed that such actions might serve the purpose of priming memory by external means, reducing the need for internal computation (e.g., mental rotation), and resulting in performance improvements that exceed the cost of taking additional actions. The present study tests this priming hypothesis in a set of four experiments. The first three explored precisely the conditions under which priming produces benefits. Results showed that presentation of multiple orientations of a shape led to faster responses than did presentation of a single orientation, and that this effect depended on the interval between preview and test. The fourth explored whether the benefit of seeing shapes in multiple orientations outweighs the cost of taking the extra actions to rotate shapes physically. Benefits were measured using a novel statistical method for mapping reaction-time data onto an estimate of the increase in processing capacity afforded by seeing multiple orientations. Cost was measured using an empirical estimate of time needed to take action in Tetris. Results showed that indeed the increase in internal processing capacity obtained from seeing shapes in multiple orientations outweighed the time to take extra actions.     

Anxiety and perceptual-motor performance: toward an integrated model of concepts, mechanisms, and processes

Under anxiety, people sometimes perform poorly. This concerns cognitive performance (e.g., taking an important exam) as well as perceptual-motor performance (e.g., picking up a cup from a table). There is still much debate about how anxiety affects perceptual-motor performance. In the current paper we review the experimental literature on anxiety and perceptual-motor performance, thereby focusing on how anxiety affects the perception, selection, and realization of action possibilities. Based on this review we discuss the merits of two opposing theoretical explanations and build on existing frameworks of anxiety and cognitive performance to develop an integrated model that explains the various ways in which anxiety may specifically affect perceptual-motor performance. This model distinguishes between positive and negative effects of anxiety and, moving beyond previous approaches, recognizes three operational levels (i.e., attentional, interpretational, and behavioral) at which anxiety may affect different aspects of goal-directed action. Finally, predictions are formulated and directions for future research suggested.     

Perceptual concepts: in defence of the indexical model

Francois Recanati presents the basic features of the *indexical model* of mental files, and defends it against several interrelated objections. According to this model, mental files refer to objects in a way that is analogous to that of indexicals in language: a file refers to an object in virtue of a contextual relation between them. For instance, perception and attention provide the basis for demonstrative files. Several objections, some of them from David Papineau, concern the possibility of files to preserve and add information about objects across contexts. How is it possible to think about the same object when the subject no longer is in the original context? How is it possible to think of a perceived object as already known? Can this be done without an explicit identity judgment? Recanati answers these questions by invoking mental files of non-basic kinds and by describing the cognitive dynamics in which they take part.     

The ability model of emotional intelligence: Searching for valid measures

Current measures of ability emotional intelligence (EI) – in particular the well-known Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) – suffer from several limitations, including low discriminant validity and questionable construct and incremental validity. We show that the MSCEIT is largely predicted by personality dimensions, general intelligence, and demographics having multiple R’s with the MSCEIT branches up to .66; for the general EI factor this relation was even stronger (Multiple R = .76). As concerns the factor structure of the MSCEIT, we found support for four first-order factors, which had differential relations with personality, but no support for a higher-order global EI factor. We discuss implications for employing the MSCEIT, including (a) using the single branches scores rather than the total score, (b) controlling for personality and general intelligence to ensure unbiased parameter estimates in the EI factors, and (c) accounting for measurement error. Failure to correctly model these methodological aspects may severely compromise predictive validity testing. We also discuss potential avenues for the improvement of ability-based tests.     

Two for the show: Anti-luck and virtue epistemologies in consonance

This essay extends my side of a discussion begun earlier with Duncan Pritchard, the recent author of Epistemic Luck.Pritchard’s work contributes significantly to improving the “diagnostic appeal” of a neo-Moorean philosophical response to radical scepticism. While agreeing with Pritchard in many respects, the paper questions the need for his concession to the sceptic that the neo-Moorean is capable at best of recovering “‘brute’ externalist knowledge”. The paper discusses and directly responds to a dilemma that Pritchard poses for virtue epistemologies (VE). It also takes issue with Pritchard’s “merely safety-based” alternative. Ultimately, however, the criticisms made here of Pritchard’s dilemma and its underlying contrast of “anti-luck” and “virtue” epistemologies are intended to help realize his own aspirations for a better diagnosis of radical scepticism to inform a still better neo-Moorean response.     

Leary's circle matrix: A comprehensive model for the statistical measurement of Horney's clinical concepts

Three issues associated with the lack of statistical evaluation of Horney's theory were presented. They are the preference for professional and clinical impression over the use of more objective methods for defining and evaluating behaviors; the difficulty involved in validly assessing the dysfunctional nature of the expansive type; and the disregard of many objective scales for intrapsychic processes that should be viewed in terms of the total "organization of personality." Leary's model was described as a systematic and formal set of procedures that are relevant and appropriate to the measurement of behavior within the context of Horney's theory. Additionally, a current study was cited that used Leary's model with significant results pertaining to the statistical implications of Leary's procedures and the adaptation of the model to Horney's theory. It is clear that any theory which presumes to provide therapeutic treatment to clients in an ethical manner must be critiqued and evaluated to safeguard the welfare of its clients. However, it is a common practice to accept therapeutic concepts that are nestled in a defined model without testing them in a relatively objective manner. With the help of Leary's circle matrix and operational procedures, it is crucial that Horney's constructs be further submitted to empirical testing on a formal basis. The procedures have been available since 1957.     

Automatic verification of multi-agent systems by model checking via ordered binary decision diagrams

We present a methodology for the verification of multi-agent systems, whose properties are specified by means of a modal logic that includes a temporal, an epistemic, and a modal operator to reason about correct behaviour of agents. The verification technique relies on model checking via ordered binary decision diagrams. We present an implementation and report on experimental results for two scenarios: the bit transmission problem with faults and the protocol of the dining cryptographers.     

Decision making in a case of mixed uncertainty: A normative model

We consider a case of uncertainty which is frequently met in various fields, e.g., in parametric statistics: Events {θ}, θ ∈ ∵, are members of family $\text{E}$ on which the decision maker possesses no information at all; however, conditionally on the realization of {θ}, he is able to affix probabilities to all members of another family of events, $\text{F}$. We assume that the decision maker: (1) has a rational behavior under complete ignorance, for decisions whose results only depend on events of $\text{E}$; (2) with {θ} known, maximizes his conditional expected utility for decisions whose results only depend on events of $\text{F}$; (3) has (unconditional) preferences which are consistent with his conditional ones. These assumptions are shown to be sufficient to ensure an approximate representation of the decision maker's preference by a real-valued function W which has the form $\text{W(f) = v[}\text{Inf}{}_{\mathrm{\theta \in \because }}\text{E}{}_{\mathrm{\theta }}\text{(u°f),}\text{Sup}{}_{\mathrm{\theta \in \because }}\text{E}{}_{\mathrm{\theta }}\text{(u°f)]}$, where u and v, respectively, characterize the decision maker's attitudes toward risk and toward complete ignorance.     

Preference for fixed-interval schedules: an alternative model

Pigeons were trained under concurrent chain schedules in which the initial links were equal aperiodic schedules and the terminal links were fixed-interval schedules. Choice proportions in the initial links were measured in 26 experimental conditions. The data showed the inadequacy of previous models of concurrent chain performance. A new model was suggested in which choice is a joint function of terminal-link times, overall reinforcement rates, and terminal-link entries. This model accounted for 94% of the variance in the present data and for substantial percentages of the variance in previously reported data. The model simplifies to matching between response ratios and obtained reinforcement rate ratios for simple concurrent schedule performance.     

A theoretical framework for understanding self-report and observational measures of pain: a communications model

Self-report and observational measures of pain are examined from the perspective of a model of human communication. This model examines the experience of pain as affected by intrapersonal and contextual factors, the process whereby it is encoded into expressive behaviour, and the process of decoding by observers prior to their engaging in action. Self-report measures primarily capture expressive pain behaviour that is under the control of higher mental processes, whereas observational measures capture behaviour that is less subject to voluntary control and more automatic. Automatic expressive behaviours are subject to less purposeful distortion than are behaviours dependent upon higher mental processes. Consequently, observational measures can be used and have clinical utility as indices of pain when self-report is not available, for example, in infants, young children, people with intellectual disabilities or brain damage, and seniors with dementia. These measures are also useful when the credibility of self-report is questioned and even when credible self-report is available. However, automatic behaviours may be more difficult for observers to decode. The model outlined herein takes into account the role of various human developmental stages in pain experience and expression and in understanding the utility of self-report and observational measures. We conclude that both observational and self-report measures are essential in the assessment of pain because of the unique information that each type contributes.     

Epistemic means and ends: a reply to Hofmann

How is epistemic justification related to knowledge? Is it, as widely thought, constitutive of knowledge? Is it merely a means to knowledge, or merely a means to something else, such as truth? In a recent article in this journal, Hofmann (2005, Synthese, 146(3), 357–369) addresses these questions in attempting to defend an important argument articulated by Sartwell (1992, The Journal of Philosophy, 89(4), 167–180) and reconstructed and criticized by Le Morvan (2002, Erkenntnis: An International Journal of Analytic Philosophy, 56(2), 151–168). This Sartwellian argument purported to show that, since epistemic justification is of merely instrumental value, it is not constitutive of knowledge. In this paper, I argue that Hofmann’s defense of Sartwell fails, but that its failure brings to light some important lessons concerning the nature of justification and its relationship to truth and knowledge.     

Expressing generic concepts with and without a language model

Utterances expressing generic kinds ("birds fly") highlight qualities of a category that are stable and enduring, and thus provide insight into conceptual organization. To explore the role that linguistic input plays in children's production of generic nouns, we observed American and Chinese deaf children whose hearing losses prevented them from learning speech and whose hearing parents had not exposed them to sign. These children develop gesture systems that have language-like structure at many different levels. The specific question we addressed in this study was whether the gesture systems, developed without input from a conventional language model, would contain generics. We found that the deaf children used generics in the gestures they invented, and did so at about the same rate as hearing children growing up in the same cultures and learning English or Mandarin. Moreover, the deaf children produced more generics for animals than for artifacts, a bias found previously in adult English- and Mandarin-speakers and also found in both groups of hearing children in our current study. This bias has been hypothesized to reflect the different conceptual organizations underlying animal and artifact categories. Our results suggest that not only is a language model not necessary for young children to produce generic utterances, but the bias to produce more generics for animals than artifacts also does not require linguistic input to develop.     

The politics of certainty: Conceptions of science in an age of uncertainty

The prestige of science, derived from its claims to certainty, has adversely affected the humanities. There is, in fact, a "politics of certainty". Our ability to predict events in a limited sphere has been idealized, engendering dangerous illusions about our power to control nature and eliminate time. In addition, the perception and propagation of science as a bearer of certainty has served to legitimate harmful forms of social, sexual, and political power. Yet, as Ilya Prigogine has argued, renewed attention to the irreducible reality of time has brought us to "the end of certainty". As we enter the age of uncertainty, there is disagreement about how science should be understood and communicated. Some scientists cling to the ideal of certainty, while others emphasize the creative potential of spontaneity, novelty, and surprise.