Temporal pattern of agonist-antagonist EMG activity during rapid limb movements in man

Analysis of elbow-extension movements, executed at maximal velocity, show positive correlations of timing of agonist-antagonist EMG activity with both movement velocity and displacement. Results indirectly support the notion that the antagonist musculature provides a braking force to arrest rapid limb movements.     

Effects of delayed conditioned reinforcement in chain schedules.

The contingency between responding and stimulus change on a chain variable-interval 33-s, variable-interval 33-s, variable-interval 33-s schedule was weakened by interposing 3-s delays between either the first and second or the second and third links. No stimulus change signaled the delay interval and responses could occur during it, so the obtained delays were often shorter than the scheduled delay. When the delay occurred after the initial link, initial-link response rates decreased by an average of 77% with no systematic change in response rates in the second or third links. Response rates in the second link decreased an average of 59% when the delay followed that link, again with little effect on response rates in the first or third links. Because the effect of delaying stimulus change was comparable to the effect of delaying primary reinforcement in a simple variable-interval schedule, and the effect of the unsignaled delay was specific to the link in which the delay occurred, the results provide strong evidence for the concept of conditioned reinforcement.     

Measuring gender differences: The expressive dimension and critique of androgyny scales

This paper calls for a new approach to the measurement of gender similarities and differences in personality. Critiques of current measures that are based on the measurement of stereotypical masculinity and femininity are reviewed, and an alternative measure is presented. It avoids many of the problems in the other scales by measuring expressiveness and instrumentality in such a way that they are not confounded with variables such as independence or autonomy. Results with this measure in five different samples are presented. These confirm our theoretical definitions of expressiveness and instrumentality, and suggest that only the expressive or relational dimension consistently differentiates samples of women and men.We thank Mary Rothbart for her insightful and constructive comments on an earlier draft; Leisha Sanders, Marcia DeCaro, Vickie Van Nortwick, and Lyn Cogswell for their clerical assistance; the Center for the Study of Women in Society for financial support; and Liza Kuecker and Patricia Gwartney-Gibbs for providing data used in the analysis. An earlier version of this paper was presented at the 1984 annual meeting of the Pacific Sociological Association.     

Repeated exposure and the attractiveness of synthetic speech: An inverted-U relationship

Previous experimental investigation of the effects of repeating an unfamiliar stimulus suggests that mere exposure breeds attraction (e.g., Zajonc, 1968). On the other hand, correlational work with naturally occurring stimuli such as names, music, or landscapes suggests that there is also an overexposure effect: the preference function does rise with familiarity at first but then reaches a turning point and diminishes. The study (N=72) demonstrates this inverted-U relationship in an experimental setting. The stimuli were synthetic nonsense speech, permitting exact control of exposure durations and interstimulus intervals. The critical factors for demonstrating the effect are probably (1) the inclusion of a large number of repetitions, and (2) blocked repetition of each stimulus in a homogeneous sequence not interspersed with other more or less frequent stimuli.     

Completion norms for 40 three-letter word stems

This is a report of the completion responses for 40 three-letter word stems (e.g., ABO) produced by 100 undergraduate students at the University of California at San Diego. The report includes a list of the different words that were written as stem completions, their frequency of occurrence as completions, and their frequency of occurrence in English according to published norms. This list of materials is useful for the construction of completion tests for future investigations of direct priming phenomena, and it may provide an important covariate in the analysis of performance on completion tests. Preliminary analyses of the results reveal three primary factors that determine overall performance on a stem-completion test: word frequency, word length, and meanings per word. Analyses of the completions produced for each individual word stem, however, reveal that usually only one of these factors makes a significant contribution to performance.     

Attitude accessibility as a moderator of the attitude-perception and attitude-behavior relations: an investigation of the 1984 presidential election

It was hypothesized that the extent to which individuals' attitudes guide their subsequent perceptions of and behavior toward the attitude object is a function of the accessibility of those attitudes from memory. A field investigation concerning the 1984 presidential election was conducted as a test of these hypotheses. Attitudes toward each of the two candidates, Reagan and Mondale, and the accessibility of those attitudes, as indicated by the latency of response to the attitudinal inquiry, were measured for a large sample of townspeople months before the election. Judgments of the performance of the candidates during the televised debates served as the measure of subsequent perceptions, and voting served as the measure of subsequent behavior. As predicted, both the attitude-perception and the attitude-behavior relations were moderated by attitude accessibility. The implications of these findings for theoretical models of the processes by which attitudes guide behavior, along with their practical implications for survey research, are discussed.     

Effect of levels of exercise on psychological mood states, physical fitness, and plasma beta-endorphin

Aerobic exercise which resulted in a significant improvement in cardiovascular functioning had no more effect on psychological mood states than did the placebo control of participation in nonaerobic recreational games or no exercise and sport at all (N = 430 college students). Beta-endorphin levels with the 41 depressed subjects were not a biochemical link that might explain the possible influence of physical activity on depression.     

Secobarbital and perceptual processing

An experiment which employed each of 18 subjects in four days of testing was used to examine acute secobarbital dose treatment effects on choice reaction time in a Cooper and Shepard (1973) character recognition task. Manipulations of visual stimulus degradation, character difficulty, 180 degree rotation, and mirror-image reversal were included in order to evaluate the hypothesis that the drug affects performance by disrupting early stimulus input processing. The results indicate significant increases in the effect of secobarbital on reaction time and errors under conditions of visual stimulus degradation. The effects of the drug, however, were not changed by 180 degree rotation of the target character or by the other task variables. The results were interpreted to indicate that secobarbital impairs performance primarily by placing selective stress on hypothetical early encoding activities and that later processing operations (associated with use of an internal representation of the target character) are not affected by the drug. Strengths and weaknesses of the two-stage model of visual stimulus processing are discussed and implications of the model for future drug research are indicated.