Threshold Models for Comparative Probability on Finite Sets

Let succeeds be a comparative probability relation on the set ℬ(S) of all subsets of a finite state space S. This paper presents and discusses necessary and sufficient axioms for several threshold models of succeeds, whose general representational form yields a probability measure P on ℬ(S) and a bivariate set function Omega>/=0 on ℬ(S)xℬ(S) such that for all A, Binℬ(S), A succeedsB if and only if P(A)>P(B)+Omega(A, B). Several conditions such as skew-monotonicity and additive separability will be imposed on the functional form of Omega. Copyright 2000 Academic Press.     

On the relationship between item response theory and factor analysis of discretized variables

Equivalence of marginal likelihood of the two-parameter normal ogive model in item response theory (IRT) and factor analysis of dichotomized variables (FA) was formally proved. The basic result on the dichotomous variables was extended to multicategory cases, both ordered and unordered categorical data. Pair comparison data arising from multiple-judgment sampling were discussed as a special case of the unordered categorical data. A taxonomy of data for the IRT and FA models was also attempted.The work reported in this paper has been supported by Grant A6394 to the first author from the Natural Sciences and Engineering Research Council of Canada.     

Choice reaction time of elbow flexion and extension during passive elbow motions

The effect of passive elbow motions on electromyographic reaction times (EMG-RTs) of the biceps brachii for elbow flexion and the triceps for elbow extension was investigated in 8 normal subjects, using a choice-RT task, in which the subject was uncertain about the response direction to perform until the arrival of response signal after the passive motion started. Compared to the static condition, choice EMG-RTs shortened only when the direction of passive and response movements was the same. It seems that passive motions act as prior information on direction of movement in the choice-RT task.     

Relative contributions of expressive behavior and contextual information to the judgment of the emotional state of another

This study used a technique for assessing the relative impact of facial-gestural expressions, as opposed to contextual information regarding the elicitor and situation, on the judgment of emotion. In Study 1, 28 undergraduates rated videotapes of spontaneous facial-gestural expressions and separately rated the emotionally loaded color slides that elicited those expressions. The source clarities of the expressions and slides were matched using correlation and distance measures, and 18 expressions and 9 slides were selected. In Study 2, 72 undergraduate receivers were shown systematic pairings of these expressions and slides and rated the emotional state of the expresser, who was supposedly watching that slide under public or private situational conditions. Expressions were found to be more important sources for all emotion judgments. For female receivers slides were relatively more important in the public than in the private situation.     

Analysis of simple reaction time to sinusoidal grating by means of a linear filter model of the detection process

Attention, Perception, & Psychophysics - Simple reaction time (RT) to a sinusoidal grating was analyzed in terms of a linear filter model of the detection process. First, RT contrast functions...     

Multilevel Dynamic Generalized Structured Component Analysis for Brain Connectivity Analysis in Functional Neuroimaging Data

We extend dynamic generalized structured component analysis (GSCA) to enhance its data-analytic capability in structural equation modeling of multi-subject time series data. Time series data of multiple subjects are typically hierarchically structured, where time points are nested within subjects who are in turn nested within a group. The proposed approach, named multilevel dynamic GSCA, accommodates the nested structure in time series data. Explicitly taking the nested structure into account, the proposed method allows investigating subject-wise variability of the loadings and path coefficients by looking at the variance estimates of the corresponding random effects, as well as fixed loadings between observed and latent variables and fixed path coefficients between latent variables. We demonstrate the effectiveness of the proposed approach by applying the method to the multi-subject functional neuroimaging data for brain connectivity analysis, where time series data-level measurements are nested within subjects.     

The analysis of multitrait-multimethod matrices via constrained components analysis

Multitrait-Multimethod (MTMM) matrices are often analyzed by means of confirmatory factor analysis (CFA). However, fitting MTMM models often leads to improper solutions, or non-convergence. In an attempt to overcome these problems, various alternative CFA models have been proposed, but with none of these the problem of finding improper solutions was solved completely. In the present paper, an approach is proposed where improper solutions are ruled out altogether and convergence is guaranteed. The approach is based on constrained variants of components analysis (CA). Besides the fact that these methods do not give improper solutions, they have the advantage that they provide component scores which can later on be used to relate the components to external variables. The new methods are illustrated by means of simulated data, as well as empirical data sets.This research has been made possible by a fellowship from the Royal Netherlands Academy of Arts and Sciences to the first author. The authors are obliged to three anonymous reviewers and an associate editor for constructive suggestions on the first version of this paper.     

Critical role of foreground stimuli in perceiving visually induced self-motion (vection)

The effects of a foreground stimulus on vection (illusory perception of self-motion induced by a moving background stimulus) were examined in two experiments. The experiments reveal that the presentation of a foreground pattern with a moving background stimulus may affect vection. The foreground stimulus facilitated vection strength when it remained stationary or moved slowly in the opposite direction to that of the background stimulus. On the other hand, there was a strong inhibition of vection when the foreground stimulus moved slowly with, or quickly against, the background. These results suggest that foreground stimuli, as well as background stimuli, play an important role in perceiving self-motion.     

Synchronization error in bilateral simultaneous flexion of elbows.

Using 7 left- and 7 right-handed subjects, the difference in time between left and right arms in the initiation of bilateral simultaneous flexion of elbows (synchronization error) was measured under three conditions: response to a sound stimulus with a warning signal, response to a sound stimulus without a warning signal, and self-initiated trial (option). The absolute value of synchronization errors depended upon experimental conditions. In conditions 'with warning' and 'option' the dominance shown in performance of left-handed subjects was the mirror-image of that shown by the right-handed subjects. The right biceps muscle responded faster in left-handed subjects and vice versa. Right-handed subjects showed rather a constant value in their dispersion of synchronization errors.