Confirming the latent structure and base rate of schizotypy: a taxometric analysis.

Meehl's (1962, 1990) model of schizotypy and the development of schizophrenia implies that the structure of liability for schizophrenia is dichotomous and that a "schizogene" determines membership in a latent class, or taxon (Meehl & Golden, 1982). The authors sought to determine the latent structure and base rate of schizotypy. They applied Meehl's (1973; Meehl & Golden, 1982) MAXCOV-HITMAX taxometric analytic procedures to a subset of items from the Perceptual Aberration Scale (PAS; Chapman, Chapman, & Raulin, 1978), a prominent psychometric index of schizotypy, derived from a randomly ascertained nonclinical university sample (N = 1,093). The results, in accordance with Meehl's conjectures, strongly suggest that schizotypy, as assessed by the PAS, is taxonic at the latent level with a general population taxon base rate of approximately .10.     

Inaccurate reporting and inappropriate variables: a reply to Vecchio's (1990) examination of cognitive resource theory.

In an article in the Journal of Applied Psychology, Vecchio (1990) purported to test cognitive resource theory (Fiedler, 1986; Fiedler & Garcia, 1987). We present evidence that Vecchio's article seriously misrepresented previous work on cognitive resource theory and also contained several flaws in methodology that call into question his conclusions regarding the validity of cognitive resource theory.     

Cognitive Biases in Playing the Lottery: Estimating the Odds and Choosing the Numbers

Three experiments were conducted to examine the operation of the representativeness and anchoring and adjustment heuristics in lottery play. Subjects in Experiments 1 and 2 indicated their chances of winning a lottery with an objective probability of 1 in 10. Consistent with the anchoring and adjustment heuristic, subjects (in both experiments) perceived their chances of winning to be greater when the lottery was based on a single event than when it was based on a disjunctive event. Subjects in these two experiments also selected numbers to play in a pick-3 (Experiment 1) or pick-4 (Experiment 2) lottery. Consistent with the representativeness heuristic, subjects in Experiment 2 demonstrated a preference for numbers without repeating digits. This also occurred in Experiment 3 wherein the numbers actually played in the Indiana daily Pick-3 lottery were examined.     

The Discrediting Effect in Eyewitness Testimony1

Loftus (1974) had subjects read summaries of criminal trials that contained the testimony of either credible or discredited prosecution eyewitnesses, and found no effect of discrediting an eyewitness. Instead, almost as many subjects voted guilty with a discredited eyewitness as with a credible eyewitness; this led Loftus to the conclusion that jurors tend to overbelieve eyewitness testimony. Loftus's conclusion was subsequently challenged by others who reported a strong discrediting effect. A series of three experiments using college students was conducted to explore the characteristics of trial summaries that might account for the discrepancy in results, such as inclusion of judicial instructions concerning proof beyond a reasonable doubt, or an eyewitness's reaffirmation of his testimony following discrediting. In all cases, a strong discrediting effect was found. Apparently the discrediting effect appears regardless of wide variation in content of trial summaries. The present data do not support the overbelief claim.     

Assessing attributions in marriage: the relationship attribution measure.

A brief, simple measure of different types of attributions for partner behavior was examined in 3 studies of married couples. Reliability was established by high internal consistency and test-retest correlations. Causal and responsibility attribution scores correlated with marital satisfaction, attributions for marital difficulties, and attributions for actual partner behaviors generated by spouses. Responsibility attributions were related to (a) reported anger in response to stimulus behaviors used in the measure and (b) the amount of anger displayed by wives during a problem-solving interaction with their partner. The extent to which husbands and wives whined during their discussion also correlated with their responsibility attributions. The results address several problems with existing assessments, and their implications for the measurement of attributions in marriage are discussed.     

Evidence for an error deadzone in compensatory tracking

Humans and monkeys show intermittent arm movements while tracking moving targets. This intermittency has been explained by postulating either a psychological refractory period after each movement and/or an error deadzone, an area surrounding the target within which movements are not initiated. We present a technique to detect and quantify the size of this deadzone, using a compensatory tracking paradigm that distinguishes it from a psychological refractory period. An artificial deadzone of variable size was added around a visual target displayed on a computer screen. While the subject was within this area, he received visual feedback that showed him to be directly on target. The presence of this artificial deadzone could affect tracking performance only if it exceeded the size of his intrinsic deadzone. Therefore, the size of artificial deadzone at which performance began to be affected revealed the size of the intrinsic deadzone. Measured at the subjects' eye, the deadzone was found to vary between 0.06 and 0.38 degrees, depending on the tracking task and viewing conditions; on the screen, this range was 1.3 mm to 3.3 mm. It increased with increasing speed of the target, with increasing viewing distance, and when the amplitude of the movement required was reduced. However, the deadzone size was not significantly correlated with the subjects' level of performance. We conclude that an intrinsic deadzone exists during compensatory tracking, and we suggest that its size is set by a cognitive process not simply related to the difficulty of the tracking task.