Caffeine,impulsivity, and memory scanning: A comparison of two explanations for the Yerkes-Dodson Effect

Two explanations for the Yerkes-Dodson Effect (1908) were tested. Easterbrook (1959) proposed that arousal reduces the range of cue utilization. Thus, arousal should interfere with the capacity for simultaneous (dual) memory scans. In contrast, Humphreys and Revelle (1984) proposed that arousal facilitates sustained information transfer but interferes with short-term memory. Arousal should thus reduce the time needed to prepare to respond but increase the time needed to scan memory. Either caffeine or placebo was given to 78 subjects who differed in impulsivity. They completed three versions of a memory-scanning task: two single-task versions (physical and category matches) and one dual-task version (either type of match). As predicted by Humphreys and Revelle, relative to placebo, caffeine lowered the intercept (p<.01), suggesting facilitation of sustained information transfer, but increased the slope (p<.05), suggesting impairment of access to short-term memory, of the regression of reaction time on log-transformed memory-set size. That caffeine had a main effect on slopes and on intercepts but did not interact with type of task suggests that arousal does not necessarily disrupt dual-task performance.     

APL functions for interactive data analysis: Principal components analysis

APL functions to support principal components analysis are presented: a general-purpose function to obtain eigen values and eigen vectors, a more specialized function to convert these into the results commonly given by principal components analysis, and a user interface function that accesses filed data, offers flexibility in data selection, and produces labeled output. A brief introduction to the logic and uses of principal components analysis is included. General-purpose support functions to simplify file use and to increase the range of options available to the user are also provided.     

APL functions for interactive data analysis: Preparation of data files

APL functions to support preparation of data files are presented: a function to manage the entry of raw data, functions to display the entered data in formats convenient for checking, a function to support correction of errors, a function to organize the data into tables and file them, and a user interface function that provides menu selection of the data preparation functions. General-purpose support functions to assist in file use and in menu selection are also provided.     

Social facilitation

The effects of the presence of another individual and evaluation apprehension were independently manipulated within a 3 (alone, mere presence, observation) × 4 (none, low, medium, high evaluation) factorial design. Ten subjects (five male, five female) were randomly assigned to each of the 12 conditions. Subjects' behavioral performance on a hidden-word task and a measure of autonomic arousal were the main dependent variables. Analysis of variance results showed a significant performance difference on the hidden-word task among the four evaluation apprehension conditions as predicted. No significant effects were found for the palmar sweat conductivity measures. The results add support for the concept of evaluation apprehension as the mediating variable in producing social-facilitation effects, and suggest that arousal as an intervening variable may be multidimensional.The author wishes to thank Joseph E. McGrath, James H. Davis, and Samuel S. Komorita for their helpful comments on a previous draft of this article.     

APL functions for interactive data analysis: Graphics and labels

APL functions designed to provide labeled plots and histograms are described. Support functions that augment a data file with necessary information to label output and to maintain a common plotting scale are also described. APL code and illustrative output are presented.     

Design and organization in a computerized psychology laboratory

This paper presents six; principles of laboratory organization and design. These six principles are an outgrowth of the past 7 years’ experience in the Mathematical Models Laboratory of the Psychology Department at Indiana University. Each of the six principles is formally stated and then followed by explanation and examples.     

A quantitative description of the stimulus

A formula for the stimulus is derived. The essential postulates and assumptions are based on Gestalt theory.     

Personality and Physical Health: An Introduction

This article provides a rationale for research on personality as a contributing factor in the development of physical disease. A brief history of major developments from the 1930s to the present is then provided. Special attention is given to shifts in conception regarding whether particular dispositions are related to specific physical disorders or whether these dispositions increase general illness susceptibility. The paper ends with a brief orientation to the other papers and commentaries in this special issue.     

Relationships between locus of control,health value,and preventive health behaviors among women

This study examines the relationships between locus of control expectancies, rated health value, and reported participation in preventive health behaviors among a healthy sample of undergraduate women. The prediction that participation in preventive health behaviors would be a joint function of an internal health-related locus of control belief and holding health in high value was not supported. Instead, individuals who valued their health reported participating in a greater number of health-enhancing behaviors compared to those who valued their health less. Respondents' scores on a health value scale in combination with their rated health status proved to be better predictors of health behaviors than their locus of control beliefs. Limitations of locus of control research with young, healthy individuals are discussed and further investigation into the utility and validity of health value scales is recommended.