Two parameters of a temporally defined schedule of negative reinforcement

Temporal schedules of negative reinforcement were derived in a manner analogous to those for positive reinforcement, and two parametric studies were carried out with two of the three defining variables. With some limiting values of the defining variables, escape schedules result and data obtained at these values were similar to those obtained in escape studies. At other values of the defining variables avoidance behavior was generated.     

The effect of repetition on the perception of single letters

Single letters were presented for from one to five flashes, with S required to report what he saw after each flash. The clarity of the letter increased sharply with repetition. Since the letters were no larger than one-third of a degree in size, clarity could not have been increased by S making different fixations from flash to flash and combining them into a total percept. Nor was S guessing, since this could be ruled out by other indicators. Thus, it was concluded that repetition of the stimulus can have a direct effect on the clarity of a S’s percept of that stimulus.     

Prevalence of personality disorders among bulimics,nonbulimic binge eaters,and normal controls

We examined the comorbidity of bulimia and personality pathology among college women. Subjects included women (n=23) meeting DSM-III-R criteria for bulimia nervosa (bulimics), women (n=23) who reported binge eating but did not fulfill the criteria for bulimia nervosa (binge eaters), and women (n=23) who did not binge eat (normals). The subjects completed an assessment battery consisting of the Personality Disorders Examination and the SCID as well as the Beck Depression Inventory, the Rosenberg Self-Esteem Index, and measures of impulsivity and self-defeating tendencies. Fourteen of 23 bulimics (61%) met criterion for a personality disorder using DSM-III-R Axis II criteria. In comparison, 3 of 23 (13%) binge eaters and 1 of 23 (4%) normal subjects received an Axis II diagnosis. Borderline and self-defeating diagnoses were the predominant personality disorders in 96% of the bulimics exhibiting clinically significant personality pathology. Bulimics also exhibited significantly more depression, impulsivity, and self-defeating behavior and lower self-esteem than binge eaters and normals. The findings are discussed within a conceptual framework that posits an interaction between personality pathology and restrained eating.     

Competency,and other constructs,in right to die cases

Subjects had to make a “remove” or “do not remove” life-sustaining measures decision in three right to die cases where the patients differed in competence; for half the subjects, a living will was present in all the cases, whereas, for the other half, it was not. Subjects also gave their determinative reasons for their decisions. Support for the right to die varied by case, but not by competency, or by the presence of a living will. The subjects' reasons were highly predictive of their decisions, and related to the way case-specific facts were construed, revealing a number of disparities between the way courts and citizens construe whether the patient's condition is “terminal,” “irreversible,” and “painful,” or not. Beyond construing facts differently, the results also revealed a disparity between evolving case law and the community's “common sense justice” over a fundamental belief: whether dying is seen as private matter, outside the bounds of State intervention, or not.     

Properties of spatial representations: Data from sighted and blind subjects

Five questions concerning the properties of spatial representations are explored. (1) How accurately does a spatial representation correspond to the true scene? (2) If inaccurate, how does it differ? (3) Are representations of a familiar scene more accurate than those of an unfamiliar one? (4) Do representations of a scene currently in view differ from those retained in memory? (5) Do the representations of the blind have properties comparable to those-of the sighted? Seven sighted and 7 highly mobile blind subjects, all familiar with a room, and 6 sighted subjects unfamiliar with it, were asked to estimate the absolute distances between 10 salient objects in the room. The 14 familiar subjects made their estimates twice: while they were in the room, and while they were remote from it. Regression analyses showed that the estimates of all subjects had strong metric properties, being linearly related to true distance, with a true zero point; and multidimensional scaling showed that all subjects produced distance estimates that could be scaled in two dimensions to closely match the actual locations of the objects. Familiarity had no effect. The effect of location of testing was the same for both the sighted and the blind: all subjects displayed better spatial knowledge when tested in the room; and all subjects underestimated true distance substantially when tested out of the room. The results showed no qualitative differences as a function of blindness, at least for these highly skilled blind travelers.     

Anticipated outgroup evaluations and intergroup bias

A study is reported that tests the hypothesis that group members exhibit intergroup bias in response to the belief that outsiders will discriminate against them. To this end, two experimental conditions are included in which subjects anticipate either biased evaluations or fair evaluations respectively. In a control condition, subjects do not expect to be evaluated from an external source. Results indicated, as expected, that those who anticipated biased evaluations from an outgroup exhibited bias themselves, while those who anticipated fair evaluations exhibited outgroup favouritism. The fact that control subjects exhibited the same degree of bias as those who anticipated biased evaluations from the outgroup poses some difficulties for the hypothesized connection between anticipated discrimination and intergoup bias. Thus, it appears that intergroup bias is the rule and not the exception in an intergroup context. Nevertheless, it is clear that anticipated evaluations of outgroup members can effect intergroup bias.     

Modeling item responses when different subjects employ different solution strategies

A model is presented for item responses when different subjects employ different strategies, but only responses, not choice of strategy, can be observed. Using substantive theory to differentiate the likelihoods of response vectors under a fixed set of strategies, we model response probabilities in terms of item parameters for each strategy, proportions of subjects employing each strategy, and distributions of subject proficiency within strategies. The probabilities that an individual subject employed the various strategies can then be obtained, along with a conditional estimate of proficiency under each. A conceptual example discusses response strategies for spatial rotation tasks, and a numerican example resolves a population of subjects into subpopulations of valid responders and random guessers.The first author's work was supported by Contract No. N00014-85-K-0683, project designation NR 150-539, from the Cognitive Science Program, Cognitive and Neural Sciences Division, Office of Naval Research. We are grateful to Murray Aitkin, Isaac Bejar, Neil Dorans, Frederiksen, and Marklyn Wingersky for their comments and suggestions, and to Alison Gooding, Maxine Kingston, Donna Lembeck, Joling Liang, and Kentaro Yamamoto for their assistance with Example 2.     

The electronic teaching theater: Interactive hypermedia and mental models of the classroom

The introduction of hypermedia into the classroom presents both an opportunity to expand the power of teaching through electronic facilitation of the media and a challenge to redesign the classroom and instructional environment to exploit the enhanced features of hypermedia. This paper briefly surveys the current state of computers in the classroom and then argues that a more integrated approach is required. To this end, the concept of an electronic teaching theater is proposed which takes advantage of hypermedia and collaborative work environments. The aim of the electronic teaching theater is not to totally redesign the classroom and instructional interaction, but rather to facilitate it using well understood metaphors to lay out the dynamics of classroom interaction on the electronic media and to use the results from research in human/computer interaction to design the interface. To facilitate the application of hypermedia, a model of instructional interaction among the students, the instructors, the course material, and the products of instruction is presented. A number of component models pertaining to course preparation, lectures, note taking, and other instructional activities are then discussed that should prove useful in designing the electronic classroom. The origin of these models is the mental representation of the interaction as perceived by the teacher and the student. The idea is to start with such models as a base metaphor, to instantiate the metaphors in the electronic classroom, and then to explore innovations in the technology that go beyond the strict application of the metaphor. This work was supported in part by a grant from AT&T to the University of Maryland during the author’s visit to the Medical Research Council—Applied Psychological Unit, Cambridge, England. Appreciation is expressed to Patricia Wright and Richard M. Young for their helpful comments on this paper.