Dynamic equilibrium on a cyclic-interval schedule with a ramp

Five human subjects pressed a panel for money on a cyclic-interval schedule that arranged recurring periods of linearly increasing reinforcement rates (ramps). Response rate versus time functions for all subjects showed recurring periods of linearly increasing response rates. The responding of four of the five subjects was in phase with the reinforcement input. The remaining subject showed a two-minute phase shift. These results suggest that organisms may act like simple amplifiers on cyclic-interval schedules, that is, the form of the input signal is not changed by the organism, but is returned with amplification. By analogy with the variable-interval case, the controlling variable on cyclic-interval schedules with rate ramps may be the constant reinforcement acceleration that is arranged by the schedule.     

Tests for stability in linear structural equation systems

Interpretations regarding the effects of exogenous and endogenous variables on endogenous variables in linear structural equation systems depend upon the convergence of a matrix power series. Convergence depends upon the eigenvalues of the structural coefficient matrix. The test for convergence developed by Jöreskog and Sörbom is shown to be only sufficient, not necessary and sufficient.     

Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

Verbal self-correction behaviors of fluent and nonfluent aphasic subjects

This investigation examined the use of six explicitly defined verbal self-correction behaviors by fluent and nonfluent aphasic subjects of high and low verbal ability, and by subjects further classified into six groups according to type of aphasia (Broca's, Anomic, Wernicke's etc.). Aphasic groups, on the average, generated some type of verbal self-correction effort on more than half of their initially erroneous responses, and the proportions of these efforts did not differ between aphasic patient groups. Significant differences in self-correction success were found, however, between groups classified according to fluency and severity, as well as among the six groups based on type of aphasia. In the former case, distinctions in self-correction skill favored high-verbal-ability groups regardless of fluency classification. In the latter instance, the subgroups typically formed by less severely impaired patients (Anomic and Broca's) had significantly higher proportions of successful self-correction behaviors than those comprised of individuals with more severe involvement (Wernicke's and Broca's plus severely limiting apraxia of speech). Between-group differences for specific types of self-correction behaviors occurred rarely, but those which were found could be related to characteristics of the particular aphasic groups under consideration. Verbal self-correction behavior is discussed as a behavioral reaction to an erroneous response or dissatisfaction with the quality of an intended response. These behaviors are viewed as indicators of the intactness of an aphasic individual's self-monitoring system, and of his tolerance for responses that are qualitatively limited by his verbal deficits.     

Values,preferences, needs,work ethics,and orientations to work: Toward a conceptual and empirical integration

There have been comparatively few attempts on either the conceptual or empirical level to integrate values, preferences, needs, work ethics, and orientations to work. A rationale outlining the way these concepts can be related to each other, is presented. It is maintained that these concepts are categories of relations between humans and work. These categories are qualitatively similar and differ principally in the level of generality of the characteristics of work considered. Complete-link cluster analysis is suggested as a method of analysis compatible with the proffered rationale. Two studies are presented with data gathered during the development of two versions of Work Aspect Preference Scale (WAPS). The samples for the two studies both comprised senior high school students, controlled for sex and age, who were administered the WAPS. Study 1 had a sample of 532 while Study 2 had a sample size of 482. Both sets of data were cluster analyzed. Results indicated a very substantial amount of agreement between the two samples, particularly at the more general levels of clustering. The bipartite and tripartite groupings of vocational needs suggested by L. H. Lofquist and R. V. Dawis (Journal of Vocational Behavior, 1978, 12, 12–19) were confirmed as were the findings of J. Mortimer (Sociology of Work and Occupations, 1975, 2, 29–53). Other clusters were also identified with findings from previous research. It is concluded that the investigation of preferences at different levels of generality and the interrelation between these levels shows great promise for both the researcher and the counselor and therefore merits more research effort.     

Visual and verbal modes of information processing and their relation to the effectiveness of cognitively-based anxiety-reduction techniques

This study examined the interaction between preferred modes of information processing (visual and verbal) and two cognitively-based anxiety-reduction techniques. One technique was based on the use of images as a coping strategy while the other employed a self-instructional approach. Thirty-six subjects reporting high levels of dental fear were assigned to one of three groups (two types of treatment and a no-treatment control). One-half of the subjects in each group had been identified as preferring the visual mode of information processing while for the other half the verbal mode was preferred. After treatment, subjects viewed an anxiety-inducing videotape depicting a visit to the dentist. Results indicated that, while both treatments were significantly effective in reducing self-reports of discomfort while viewing the videotape, there was no significant interaction between the type of treatment and preferred cognitive mode. The results were interpreted as indicating that treatment may override individual cognitive styles. Furthermore, the data suggested that the normal individual has the ability to adapt to divergent and non-preferred forms of information processing.