David C. Edwards

Seven studies of performance expectancy as a determinant of actual performance

Seven experiments were performed to explore the effects of expectancy-performance inconsistency on the undoing of correct responses (Aronson and Carlsmith, 1962). Experiments 1 and 2 reproduced the Expectancy × Performance interaction; the dissonant effect of High Performance on Low Expectancy was significantly reduced from 1 to 2 by reducing the number of trials used to induce Expectancy in 2. Experiments 3 to 7 failed to yield an Expectancy × Performance interaction. Experiments 3 to 6 examined the effects of trial-by-trial feedback on expectancy strength and hypothesis invention. Experiment 7, which included conditions requiring recall of previous judgments, suggested that the repeated finding of greater response change by Low-Performance Ss may be explained by differences in memory as well as by differences in motivation to do well.

Comparison of First-Eye-Movement Detection Methods

The first eye movement from a point of fixation was detected by direct observation of the eye, by electro-oculograph (EOG), and by corneal reflection apparatus. Essential agreement was obtained among the measures. Only with movements less than 5° were there serious numbers of discrepancies in detection against the criterion of photo-recorder corneal reflection measurement. A horizontal movement was detected more reliably than a vertical movement. The EOG was most likely to miss detection of a vertical movement. The efficiency of the measures with regard to movement detection and monitoring choice-looking-behavior were discussed.

Information processing in the visual periphery

The information processing capacity of the visual periphery was investigated in two experiments using stimuli of known relative information content. The results of Experiment I showed redundant patterns to be easiest to identify at all peripheral angles tested (5, 10, 20, and 30 deg) as compared to intermediate and nonredundant patterns. Performance on all patterns decreased as peripheral angle increased. In Experiment II, simultaneous foveal and peripheral vision was required in a discrimination task. Performance was above chance only when the peripheral (7-deg) pattern was redundant. The foveal pattern had no effect on discrimination.

Within mode quality and intensity changes of habituated stimuli

Habituation of skin conductance response (SCR) magnitude was established by a number of presentations of a short burst of moderate intensity white noise. The 6th, 11th, or 21st stimulus event was either a pure tone of unchanged loudness or another noise pulse of greatly reduced loudness. Mean SCR magnitude to the reduced intensity noise pulses was consistently smaller than that to the tones, but the difference of each of these response from the habituation curve varied with the number of prior habituation trials. The qualitative changes in the stimulus produced a consistent increase in SCR magnitude; the greater the number of prior habituation trials, the larger the difference from the habituation curve. The reduced intensity noise stimulus reduced SCR magnitude below that of the habituation curve at the 6th trial, equalled the curve at the 11th trial, and yielded a greater response than the habituation curve at the 21st trial test position. The response to the tone was superior to that to the reduced intensity noise by a constant amount over the three habituation curve test points.

The effect of loud noise on the psychological refractory period

The psychological refractory period effect was measured under the effects of a loud-noise stressor. It was demonstrated that the loud noise served to exaggerate the delay in the response to the second of two successive stimuli, but the effect was not greater with short interstimulus intervals, as indicated by theory. Arousal appears to affect processing stages prior to response selection.