A Comparison of Two Multidimensional Health Locus of Control Instruments

This study examined the factor structure, internal consistency reliability and construct validity of the multidimensional health locus of control (MHLC) instruments developed by K. A. Wallston, B. S. Wallston, and DeVellis (1978) and Lau (Lau, 1982; Lau & Ware, 1981), Both measures were administered to a sample of Veterans Administration (VA) medical outpatients (N = 181). Only minimal evidence of convergence was found between corresponding scales of the two MHLC instruments. Low convergent validity appears attributable to the poor internal consistency reliability of the Lau-Ware subscales. Moreover, results of factor analysis largely supported the a priori factor structure of the K. A. Wallston et at. (1978) MHLC instrument but failed to support the factor structure of the Lau-Ware instrument, Health locus of control (HLC) dimensions that emerged from simultaneous factor analysis of both instruments were most consistent with a three-dimensional typology (i.e., Personal Control, Professional Control and Chance) rather than the four-dimensional typology proposed by Lau (Lau, 1982; Lau & Ware, 1981). Implications for HLC conceptualization and measurement are discussed.     

A Case of Synaesthesia

Two experiments employed Potential Performance Theory (PPT) to correct for inconsistency in a speeded task. In Experiment 1, a search task was employed whereby participants searched for a target letter among distracters. In Experiment 2, the search task was more complex and naturalistic—participants searched for enemy weapons in aerial photographs. Not surprisingly, the results revealed that longer search times led to greater accuracy. However, this improvement was due only in part to improved search strategies. Much, if not most, of the improvement was due to increased consistency. The authors demonstrate and discuss some of the advantages to be gained by considering a speeded task within the context of a clear and mathematically precise theory (PPT).     

The spatiotopic representation of visual objects across time

Each eye movement introduces changes in the retinal location of objects. How a stable spatiotopic representation emerges from such variable input is an important question for the study of vision. Researchers have classically probed human observers' performance in a task requiring a location judgment about an object presented at different locations across a saccade. Correct performance on this task requires realigning or remapping retinal locations to compensate for the saccade. A recent study showed that performance improved with longer presaccadic viewing time, suggesting that accurate spatiotopic representations take time to build up. The first goal of the study was to replicate that finding. Two experiments, one an exact replication and the second a modified version, failed to replicate improved performance with longer presaccadic viewing time. The second goal of this study was to examine the role of attention in constructing spatiotopic representations, as theoretical and neurophysiological accounts of remapping have proposed that only attended targets are remapped. A third experiment thus manipulated attention with a spatial cueing paradigm and compared transsaccadic location performance of attended versus unattended targets. No difference in spatiotopic performance was found between attended and unattended targets. Although only negative results are reported, they might nevertheless suggest that spatiotopic representations are relatively stable over time.     

A comparison of the effects of partial reinforcement schedules using a within-subject serial autoshaping procedure

Three experiments, each using a single group of pigeons, are reported. In Experiment 1 subjects were initially trained with two stimuli, one of which was always followed by food, the other being reinforced according to a 50% partial reinforcement schedule. Subsequently a serial procedure was adopted in which an additional stimulus, C, was consistently followed by the partially reinforced CS. A second additional stimulus, A, was followed on half of its occurrences by the continuously reinforced CS, its remaining presentations being followed by nothing. The rate of autoshaped keypecking was substantially greater during A than during C. In the remaining experiments subjects received first-order conditioning with a single stimulus that was either partially (Experiment 2) or continuously (Experiment 3) reinforced. The stimuli A and C were then again introduced for serial autoshaping. Stimulus A was occasionally paired with the CS and occasionally followed by nothing, whereas stimulus C was always followed by the CS. As in Experiment 1, the rate of responding during A was greater than during C. It is proposed that one influence on the rate of autoshaped keypecking during a CS is the accuracy with which the immediate consequences of that CS are predicted.     

Testing for adverse impact when sample size is small

Adverse impact evaluations often call for evidence that the disparity between groups in selection rates is statistically significant, and practitioners must choose which test statistic to apply in this situation. To identify the most effective testing procedure, the authors compared several alternate test statistics in terms of Type I error rates and power, focusing on situations with small samples. Significance testing was found to be of limited value because of low power for all tests. Among the alternate test statistics, the widely-used Z-test on the difference between two proportions performed reasonably well, except when sample size was extremely small. A test suggested by G. J. G. Upton (1982) provided slightly better control of Type I error under some conditions but generally produced results similar to the Z-test. Use of the Fisher Exact Test and Yates's continuity-corrected chi-square test are not recommended because of overly conservative Type I error rates and substantially lower power than the Z-test.