A general approach to confirmatory maximum likelihood factor analysis

We describe a general procedure by which any number of parameters of the factor analytic model can be held fixed at any values and the remaining free parameters estimated by the maximum likelihood method. The generality of the approach makes it possible to deal with all kinds of solutions: orthogonal, oblique and various mixtures of these. By choosing the fixed parameters appropriately, factors can be defined to have desired properties and make subsequent rotation unnecessary. The goodness of fit of the maximum likelihood solution under the hypothesis represented by the fixed parameters is tested by a large samplex ² test based on the likelihood ratio technique. A by-product of the procedure is an estimate of the variance-covariance matrix of the estimated parameters. From this, approximate confidence intervals for the parameters can be obtained. Several examples illustrating the usefulness of the procedure are given.This work was supported by a grant (NSF-GB 1985) from the National Science Foundation to Educational Testing Service.     

PSYCHOPHYSIOLOGICAL REACTIONS TO TWO DIFFERENT PLACEBO TREATMENTS

Reactions to a placebo introduced either as a depressant or as a stimulant drug were examined in 16 healthy female subjects. Comparisons between pre- and post-placebo measurements showed that the two treatments produced marked effects in opposite directions: (1) the 'depressant' placebo produced a statistically significant decrease in pulse rate, blood pressure, objective and subjective reaction speed, as well as significant effects on subjective mood in the expected directions, and (2) the 'stimulant' placebo produced opposite and significant changes in all variables. The subjective reactions were, on the whole, more pronounced than the effects on performance and physiological functions.     

AN EMPIRICAL APPLICATION OF A NEW CASE OF THE LAW OF COMPARATIVE JUDGMENT

A case of the law of comparative judgment which does not assume equal variances and covariances has been applied in the scaling of conservatism from seven attitude scale items. The scale values are in good agreement with those computed from previously known cases. There is also some covariation between comparatal dispersions from Case IV and the new case.     

AUTONOMIC INDICES OF HABITUATION TO COMPLEX AND SIMPLE STIMULI

Skin conductance and heart rate were continuously recorded in 8 subjects repeatedly exposed to a perceptual-conflict test and to auditory signals. (1) Both complex and simple stimuli gave rise to a pronounced increase in skin conductance, the magnitude of response decreasing with number of repetitions. For both types of stimuli a linear relationship was obtained when GSR, measured as the change in log conductance, was plotted against the logarithm of the stimulus number. (2) Each presentation of the conflict test increased heart rate, magnitude of change decreasing approximately linearly with number of trials.     

SUBJECTIVE TIME AS AFFECTED BY GRAVITATIONAL STRESS

Subjective time as affected by positive radial acceleration in a human centrifuge was studied by a modification of the method of ratio production. Auditory signals (1–20 sec.) were used as stimuli. The results showed a marked change in subjective time during gravitational stress. Subjective time, as measured by the methods employed, was a positively accelerated function of objective time and the positive acceleration was enhanced during centrifugation. The demonstrated change in time experience was caused by a difference in retention of preceding time intervals, retention being impaired during centrifugation.     

THE INFLUENCE OF INTENSITY AND DURATION OF ELECTRICAL STIMULATION ON SUBJECTIVE VARIABLES

The unpleasantness and subjective duration of an A.C. current of 50 c/sec applied to two fingers was scaled by subjects using the method of magnitude estimation. Stimulation was varied with regard to both intensity and duration. It was found that (1) unpleasantness increased logarithmically with stimulus duration, (2) unpleasantness was a power function, with the exponent 1.5, of stimulus intensity, (3) subjective duration was essentially linearly related to stimulus duration, and (4) subjective duration increased logarithmically with intensity of stimulation.     

A method for sensation scaling based on an analogy between perception and judgment

Two techniques for studying judgment are discussed. In the first of these one assumes invariance of perception over different judgment processes and conceives of the properties of one judgment process as known. Then, perceptions may be estimated under this process and utilized in the study of other judgment processes of interest. A second technique disposes of the reliance up on a basic, “known” process and instead suggests that perception be treated as free parameters to be estimated from data. The paper then proceeds to show how this second technique may be used under certain conditions on perception themselves. A concept of sensation is introduced which is thought of as generating percepts in formally the same manner as percepts are thought of as generating judgments. The idea is tried out on the perception of movement time. A simple perception process appears to give a good fit to data.     

STUDIES IN THE PSYCHOLOGICAL EFFECTS OF A NEW DRUG (DIETHYLPROPION): Subjective effects in the natural environment

Two doses diethylpropion, one dose pipradrol, one dose amobarbital and placebo were administered to 116 subjects, who rated their state on twenty variables. The variables were intercorrelated under pipradrol and pentymal. The correlation matrices were subjected to factor analysis. Four factors were found in both studies: Happiness, Alertness, Relaxation, and Flight of thoughts. There is some agreement between the two factor analyses. There were few significant effects of the drugs on factor scores, but the structure is quite unambiguous: pipradrol and diethylpropion are stimulating, and amobarbital tranquilizing.