Effects of surface texture and grip force on the discrimination of hand-held loads

In this paper, we report the results from two experiments in which subjects were required to discriminate horizontal load forces applied to a manipulandum held with a precision grip. The roughness (and hence friction) of the grip surfaces and required grip force were manipulated. In the first experiment, subjects were instructed to judge the load while maintaining hand position and not letting the manipulandum slip. It was found that performance was influenced by surface texture; a given load was judged to be greater when the surface texture was smooth than when it was rough. This result is consistent with a previous study based on lifting objects and indicates that the effect of surface texture applies to loads in general and not just to gravitational loads (i.e., weight). To test whether the load acting on a smooth object is judged to be greater because the grip force required to prevent it from slipping is larger, a second experiment was carried out. Subjects used a visual feedback display to maintain the same grip force for smooth and rough manipulandum surfaces. In this case, there was no effect of surface texture on load perception. These results provide evidence that perceived load depends on the grip force used to resist the load. The implications of these results in terms of central and peripheral factors underlying load discrimination are considered.     

Introductory psychology laboratories using graphic simulations of virtual subjects

Graphical simulations of the behavior of virtual subjects in laboratory or field microworlds were developed to teach research principles to introductory psychology students. Students conduct studies in laboratory classes, assuming the primary role of being an experimenter. Microworld modules were designed to foster the flexible exploration of important steps in the research process, including hypothesis generation, research planning and design, behavioral observation or testing, and data summarization and analysis. The modules were designed to impart a sense of behavioral “presence” so that students would obtain an appreciation of realistic behavioral observation and of testing methodologies. Microworlds that have been developed include infant preferential looking (cognitive processes), courting behavior of fireflies, personality test development, working memory, operant conditioning, single-cell recording of sensory function, and testing of brain-damaged people. Principles that guided the development of software modules and laboratory class exercises are discussed.     

Majority Group Perceptions of Criminal Behavior: The Accuracy of Race-Related Crime Stereotypes1

Majority group perceptions regarding the relative frequency of crimes committed by various races and ethnic groups were examined. White-collar crimes such as embezzlement and fraud were ranked as more common for White criminals, and blue-collar crimes such as aggravated assault and motor vehicle theft were ranked as more common for Black criminals. Perceptions were subsequently compared with data from the Uniform Crime Reports for the U.S. (U.S. Department of Justice, 1992). As a function of overestimating the number of white-collar crimes and underestimating the number of blue-collar and violent crimes committed by Whites, majority group subjects held somewhat more accurate perceptions of minority groups than of their own group.     

Organizational Commitment: Clarifying the Concept and Simplifying the Existing Construct Typology

This paper examines popular concepts and “types” of organizational commitment in light of the definition of commitment and common factors that pertain to all commitments. It argues that a commitment is best conceptualized as a single, fundamental construct that may vary according to differences in focus, terms, and time-specific evaluation. Analysis of affective commitment measures indicates that certain measures contain more than one set of terms and make assumptions about evaluation that add constraints to the basic meaning of commitment. Recommendations include the argument that commitment measures address one set of terms and avoid evaluative phraseology.     

Patterning,partial reinforcement,and N-length effects at spaced trials as a function of reinstatement of retrieval cues

Four experiments are reported which demonstrate the importance of the reinstatement of retrieval cues in partial-reinforcement experiments using spaced trials. Reinstatement occurs when the goalbox and startbox are of the same brightness (gray). Nonreinstatement occurs when the goalbox and startbox are of different brightnesses (black-and-white striped vs gray). Under reinstatement conditions, both a partial-reinforcement effect (PRE) and N-length effects were observed whether small reward or large reward was used. Under nonreinstatement conditions, a PRE was observed when large reward was used but not when small reward was used; N-length effects were not observed either with large or small reward. Finally, using a 24-hr intertrial interval, single alternation patterning was found only with a group receiving large reward, a long nonreward confinement duration, and reinstatement. These results are not consistent with the notion that massed and spaced trials are governed by separate mechanisms, and support an explanation of both massed and spaced trials based on E. J. Capaldi's sequential theory.     

Arousal and imitation of aggression

Forty boys, aged 5 and 6 years, viewed either an aggressive or nonaggressive film and were tested for imitation of the behavior displayed in the film. On the next day, before being tested again for imitation of the film, half the subjects in each film condition engaged in arousing play with the experimenter, and half in quiet play. According to the prediction, those aroused on the second day displayed more imitative behavior than those not aroused, regardless of which film they had seen. The results are discussed in terms of arousal as a performance variable in social learning.Thanks are due to Louis Morris, for advice and suggestions, and to Jeffrey Cohen, for assistance in data collection. This research was facilitated by funds from the Tulane University Council on Research.     

A developmental study of the Prelinguistic Auditory Store (PAS)

Lists of digits 5 and 7 items in length were presented to second graders, sixth graders, and low-IQ sixth graders in either the visual or auditory modality. Half the auditory lists were followed by the redundant nonrecalled, auditorily presented word “recall” which served as a list suffix. The second graders had the most errors in the ordered recall task followed by the low-IQ sixth- and normal sixth-graders in that order. The size of the modality and suffix effects for the various groups seemed to indicate that, for the younger subjects, a larger proportion of the recall after auditory presentation comes from the Prelinguistic Auditory Store than for the older subjects.     

Cardiovascular dynamics during classical appetitive and aversive conditioning in laboratory primates

This report describes changes in the rate of rise of left and right intraventricular pressures during aversive and appetitive conditioning procedures in chair-restrained rhesus monkeys. The conditioning paradigm consisted of a one-minute tone followed, in the one case, by an electric shock, and in the other, by the delivery of Purina monkey pellets. The conditional cardiovascular response was characterized by short latency, highly significant elevations in the derivatives of both ventricular pressures as well as a marked arterial pressor response and tachycardia. The magnitude of the conditional response to the classical aversive procedure was somewhat larger than that to appetitive conditioning. These alterations in the rate of development of intraventricular pressure can be attributed largely to augmentation in the sympathetic neural input to the heart and contribute to an analysis of selective aspects of the nervous regulation of the heart in intact, behaviorally conditioned animals.     

Anxiety management training in the treatment of essential hypertension

The study was conducted to assess the efficacy of Anxiety Management Training as an adjunctive treatment for essential hypertension. Twenty-one patients with essential hypertension, all but one of whom were on antihypertension medication, were randomly assigned either to an Anxiety Management Training condition or a waiting-list control condition. At the time of a posttest assessment session, compared to subjects in the control condition, subjects in the Anxiety Management Training condition manifested a decrease in resting systolic and diastolic blood pressure and a decrease in systolic and diastolic blood pressure following a stressful task. At the time of a follow-up assessment session, subjects in the Anxiety Management Training condition not only manifested good maintenance of reduced blood pressure but also exhibited a further decrease in resting systolic blood pressure and a decrease in systolic blood pressure during the stressful task.     

Cardiac arrhythmias in the monkey during classically conditioned fear and excitement

Rhesus monkeys(Macaca mulatto) were tested in classic aversive and appetitive conditioning paradigms following complete coronary artery occlusion (CO) to test the hypothesis that “emotional stress” induces ventricular arrhythmias. Findings were based upon conditioning trials conducted for one or more weeks after occlusion in 13 animals. When all data from each animal for the week following CO were considered, there was no demonstrable tendency for arrhythmias to increase during “fear” conditioned to unavoidable electric shock or during “excitement” in anticipation of food. However, selected trials from six monkeys did reveal instances when changes in the frequency of occurrence of arrhythmias were coupled with behavioral conditioning. While analysis of these trials did not reveal any simple relationship between emotional stress and the development of ventricular arrhythmias after myocardial infarction, certain of the behavioral situations may be more potentially arrhythmogenic than others. For these selected trials, with respect to control, the number of arrhythmias may have increased or decreased upon presentation of the conditional stimulus; the exact response appears to depend upon the immediate physiologic status of the animal as well as on the behavioral condition. “More stressful” situations, such as aversive conditioning, are not necessarily associated with greater numbers of arrhythmias than were “less stressful” situations, such as appetitive conditioning. Arrhythmias appear to occur more frequently when an animal’s heart rate is within a given range; this may reflect underlying cardiac sympathetic and parasympathetic nerve activity.