Effect of delay-interval stimuli on delayed symbolic matching to sample in the pigeon

In Experiment 1, food-deprived pigeons received delayed symbolic matching to sample training in a darkened Skinner box. Trials began with the illumination of the grain feeder lamp (no food sample), or illumination of this lamp, accompanied by the raising of the feeder tray (food sample). After a delay of a few seconds, the two side response keys were illuminated, one with red and one with green light, with positions counterbalanced over trials. Pecking the red (green) comparison produced grain reinforcement if the trial had started with food (no food); pecking red after a no-food sample or green after a food sample was not reinforced. Once matching performance was stable, four stimuli were presented during the delay interval, and their effects on matching accuracy were evaluated. Both illumination of the houselight and the center key with white geometric forms decreased matching accuracy, whereas presentation of a tone and vibration of the test chamber did not. In Experiment 2, pecking the red center key was reinforced with food according to a variable interval schedule. The effects of occasional brief presentations of the four stimuli used in the first experiment on ongoing pecking were assessed. The houselight and form disturbed key pecking, but the tone and vibration did not. Thus, stimuli that interfered with delayed matching also interfered with simple operant behavior. Implications of these results for theories of remembering are discussed.     

Economic substitutability of electrical brain stimulation, food, and water.

Concurrent variable-ratio schedules of electrical brain stimulation, food, and water were paired in various combinations as reinforcement of rats' lever presses. Relative prices of the concurrent reinforcers were varied by changing the ratio of the response requirements on the two levers. Economic substitutability, measured by the sensitivity of response ratio to changes in relative price, was highest with brain stimulation reinforcement of presses on both levers and lowest with food reinforcement of presses on one lever and water reinforcement of presses on the other. Substitutability with brain stimulation reinforcement of presses on one lever and either food or water reinforcement for presses on the other was about as high as with brain stimulation for presses on both levers. Electrical brain stimulation for rats may thus serve as an economic substitute for two reinforcers, neither of which is substitutable for the other.     

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.     

The life and times of PSI

This paper describes the essential features of the personalized system of instruction (PSI). Results from outcome research examining the effectiveness of PSI-based courses relative to traditional methods provide unequivocal support for the superiority of PSI. Parametric studies, or component analyses, show that the mastery requirement, immediate performance feedback, and review units are the key features underlying high quality student performances in PSI courses. The use of student proctors as peer-tutors, optional lectures, and selfpacing do not, in and of themselves, appear to be vital to student success in PSI courses. Despite its superiority, PSI has not supplanted traditional methods as the dominant pedagogical system in higher education. Difficulties inherent in overcoming the inertia of the lecture within our established instructional system, the implications of PSI for that system, and the Zeitgeist that permeates educational reform are the major obstacles to widespread adoption of PSI.     

Reforming mathematics instruction: The role of curriculum materials

The crisis in mathematics education is likely to grow. One of the targets for reform is the math textbook, which largely defines the math curriculum. Several aspects of math textbooks that strongly influence student learning are explained: the organization of lessons, the use of time, the rate of introducing new concepts, the quality of instructional activities, the nature of the examples, and the provision of guided and independent practice. Excerpts from math texts illustrate these factors. Research findings on an alternative to basais, represented by the Direct Instruction math curriculum, illustrate how conceptual understanding and proficiency can be developed for a full spectrum of students.     

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.