Kenneth O. McGraw

Evidence of a detrimental effect of extrinsic incentives on breaking a mental set.

Abstract College students were either rewarded (

The Integrity of Web-Delivered Experiments: Can You Trust the Data?

1.50) or not for solving a series of 10 water-jar problems. The first 9 of these were designed to establish a set for a relatively complicated, three-jar solution (B − A − 2C). The 10th problem was a set breaker which required that subjects discover a simple (A-C) solution. The mental activities needed to produce a solution to the two types of problems (Problems 1 to 9 and Problem 10) were, therefore, different and one interest was in seeing whether reward would be detrimental for performance on both types of problems. It was not. Poorer reward group performance was obtained only on Problem 10. This result was not due to between-group differences in mathematical ability, and explanations in terms of differences in time taken to check answers or concern over quality of performance were considered and discounted. Measures of intrinsic interest (subject evaluations of the task and a measure of willingness to volunteer for future research) failed to support the belief that interest differences account for performance differences.

The Relative Salience of Sex, Race, Age, and Glasses in Children's Social Perception

Data from Web-delivered experiments conducted in browsers by remote users of PsychExperiments, a public on-line psychology laboratory, reveal experiment effects that mirror lab-based findings, even for experiments that require nearly millisecond accuracy of displays and responses. Textbook results are obtained not just for within-subjects effects, but for between-subjects effects as well. These results suggest that existing technology is adequate to permit Web delivery of many cognitive and social psychological experiments and that the added noise created by having participants in different settings using different computers is easily compensated for by the sample sizes achievable with Web delivery.

PsychExps: An Online Psychology Laboratory

The relative salience for children of various human facial features was examined in five experiments. The first two experiments were designed to validate the conclusion from previous research (McGraw, Durm, & Patterson, 1983) that the sex of adult faces is more salient than their race or age, and that the presence or absence of glasses is extremely unsalient. Childrens spontaneous verbal descriptions confirmed the salience hierarchy of sex, race, age, and glasses. Experiments 3, 4, and 5 were designed to ascertain whether the salience of race, glasses, and age would be stable across potentially relevant subject and task-stimuli differences. There were some salience asymmetries; most notably, black skin was more salient than white skin for both Black and White children. In general, the results of these studies indicate that sex, race, age, and glasses represents a naturally occurring salience hierarchy that is reliably present among children of preschool and early elementary school age.

Confidence Intervals and F Tests for Intraclass Correlations Based on Three-Way Random Effects Models

Publisher Summary PsychExps is an online undergraduate laboratory that is currently available for use. Experiments can be conducted and data collected, just as in traditional labs that use experiment packages or other software for conducting experiments in which students participate as subjects. This chapter discusses the rationale for PsychExps, along with an overview of the technology behind PsychExps. It also highlights the future plans of PsychExps. The interactivity afforded by programs that can be run over the Internet has led to a wealth of online activities. Such sites take experimentation on the Web beyond forms-based data collection to true interaction. Among the obvious advantages of Web-based experiments is that they free students from having to come to a fixed site at a fixed time to perform their lab activities. In addition to convenience, ease of access makes it easier to recruit participants, and data collection can be performed in parallel from multiple sites. Web-based experiments make it possible to fit more data gathering into a fixed time period, and perhaps most important, having a single Web-based implementation of an experiment allows data to be pooled across research sites and across time. With data pooling, the types of questions addressed in laboratory work can be answered using large data sets in place of the typical small ones.

UNDERGRADUATE LABS AND COMPUTERS : THE CASE FOR PSYCHEXPS

This article gives equations for computing confidence interval estimates and conducting F tests for intraclass correlation coefficients (ICCs) defined using three-way random effects models for crossed and nested designs. The estimates and tests employ mean squares from analyses of variance. The equations are generalized so that data from an initial pilot study (G study) can be used to prophesy the confidence limits for ICCs in data with more or fewer factor levels. Equations also are included for determining the optimal number of factor levels to use in a design that will offer confidence of 1-[.alpha] that the population ICC is equal to or exceeds a fixed lower limit.

Concept discrimination learning by preschool children using facial stimuli differing in age, sex, race, and eyeglasses.

PsychExps (http://www.olemiss.edu/PsychExps) is an interactive on-line psychology laboratory designed to facilitate teaching and conducting research over the Internet. With the increased use of the Web among students and the development of technology enabling the deployment of experiments via the Internet, a laboratory such as PsychExps appears to offer numerous advantages over the solely classroom-based laboratory. As part of the development of PsychExps, a survey was conducted, to assess the utility of this novel approach to the traditional computer-based psychology laboratory classes. Responses generally indicate interest in and a need for cost-effective resources such as an Internet-based laboratory. In addition, PsychExps offers several advantages over the mostly pedagogical and demonstration-based psychology sites on the Internet.

How Many Subjects to Screen? A Practical Procedure for Estimating Multivariate Normal Probabilities for Correlated Variables.

In two experiments, the relative salience of the variables age, sex, race, and eyeglasses was determined with the use of a discrimination learning task and preschool-age Ss. The stimuli for the task were 112 frontal head and shoulder color photographs arranged in pairs. In both experiments, sex discrimination was the easiest to learn, followed by race and age, which did not differ from each other. Each of the variables of sex, age, and race, however, proved to be more salient than glasses which was not learned by any of the 19 Ss who were given a glasses discrimination problem in Experiment 1. Interestingly, specific cue salience may be a more valid concept than dimensional salience for preschool children. This was indicated by the asymmetry in performance on the black and white racial discrimination problems and on the male and female sexual discrimination problems: both black and male were significantly easier to learn.

The Apparent Distance of Interior and Exterior Corners: A Test of Gregory's Misapplied Size Constancy Explanation for the Mueller-Lyer Illusion

This article suggests a practical procedure for estimating the number of Ss that need to be screened to obtain a sample of fixed size that meets multiple correlated criteria. The procedure is based on the fact that least squares regression provides a good quadratic fit for Monte Carlo estimates of multivariate probabilities when they are plotted as a function of mean pairwise correlations (r) for the criterion variables. The equations given here can be used to predict selected 3- to 5-variable joint probabilities with reasonable accuracy as long as pairwise correlations for the selection criteria range from .10 to .90.

The effect of monetary incentives on backward digit span performance

Key to Gregorys misapplied size constancy explanation for the Mueller-Lyer illusion is the assumption that subjects perceive the central line segment of the fins-out figure, which is analogous to an interior corner, as projecting from a more distant object than does the central line segment of the fins-in figure, which is analogous to an exterior corner. We examined the validity of this assumption by having 20 college students judge the relative distance of three-dimensional model corners, presented in a monocular viewing box. The interior corner was perceived to be nearer than the exterior corner, indicating that the key assumption in Gregorys theory is either false or unfalsifiable.