Self-selection biases in correlational studies based on questionnaires

It is commonly held that even where questionnaire response is poor, correlational studies are affected only by loss of degrees of freedom or precision. We show that this supposition is not true. If the decision to respond is correlated with a substantive variable of interest, then regression or analysis of variance methods based upon the questionnaire results may be adversely affected by self-selection bias. Moreover such bias may arise even where response is 100%. The problem in both cases arises where selection information is passed to the score indirectly via the disturbance or individual effects, rather than entirely via the observable explanatory variables. We suggest tests for the ensuing self-selection bias and possible ways of handling the ensuing problems of inference.The author would like to thank members of the Psychology Department at UWA for references on the illustrative example, namely the effects of sex-stereotyping on achievements in mathematics; thanks are also due to the anonymous reviewers whose comments resulted in material improvements to the paper.     

Conceptual fallacies in subjective probability

Subjective probability considered as a logic of partial belief succumbs to three fundamental fallacies. These concern the representation of preference via expectation, the measurability of partial belief, and the normalization of belief.     

The Novacco Anger Scale and Jenkins Activity Survey as predictors of cardiovascular reactivity

This study investigated the relationship among anger, the Type A construct, and cardiovascular reactivity. The Novacco Anger Scale and the Jenkins Activity Survey (JAS) were used to measure anger proneness and Type A characteristics, respectively. Twenty-four college males were selected from the upper and lower quintiles of the JAS distribution. During the study, the subjects were exposed to varying levels of experimentally induced challenge, while measurements were taken of heart-rate and blood-pressure changes. The results showed a modest but significant correlation between scores on the Novacco Anger Scale and the JAS. More importantly, scores on the Novacco Anger Scale correlated significantly with heart rate and systolic blood pressure under all challenge conditions, while those on the JAS were unrelated to cardiovascular excitability. These results raise questions about the usefulness of the JAS as a predictor of CHD risk. They are also consistent with the beliefs of other investigators that anger and hostility are the most important Type A behaviors in predisposing patients to coronary heart disease. Additional implications of the study are discussed.     

An inexpensive real-time microcomputer-based cognitive laboratory system

A computer system, based on the Radio Shack Color Computer, for running experiments in cognitive psychology is described. The system was designed according to the following principles: first, all of the equipment should consist of inexpensive, off-the-shelf components; second, the language used to implement experiments should have real-time commands embedded within the character strings to be displayed, and these real-time commands should be interpreted at run time; third, the system should serve multiple subjects, yet one host should be able to run display terminals for several subjects on independent experiments; and fourth, the system should be able to interface to other display devices and other response-recording devices. Two examples of other devices are discussed: an oscilloscope for rapid visual display and an Apple Macintosh for display of pictures.     

An electronic device for detecting activity in caged rodents

An electronic device for detecting movement in small animals is described. The principle involves assessing changes in resistance between pairs of grid bars in a cage. The device is inexpensive, sensitive to movement, easy to calibrate and install, reliable across different activity arenas, and indifferent to animal size.     

Lateral asymmetry of personal optimism

By combining models of cerebral emotional asymmetry and unilateral hemispheric activation, it was hypothesized that orienting to the right would produce greater personal optimism about future events than would orienting toward the left. This was supported significantly in two experiments which differed from each other in their manipulations, hypothetical future events, means of responding, and settings. The results supported previous research on unrealistic optimism and extended the concept to show the effect of induced lateral orientation. It was proposed that this effect is mediated by mood, and possibly by perceived control, and that this methodology can be extended to other behaviors which have proven amenable to mood manipulation.     

A preliminary study of Hare's “Research Scale for the Assessment of Psychopathy” in mentally-abnormal offenders

The abbreviated (15-item) version of Hare's Research Scale for the Assessment of Psychopathy (RSAP) was investigated in a sample of male admissions to Broadmoor Special Hospital (N = 50), along with five MMPI measures relevant to psychopathy (Impulsivity, Sociability, Psychopathic Deviate, Anxiety and Sociopathy). Patients were assigned to one of four clinical diagnostic groups: Personality Disorder, Mixed (personality disorder with schizophrenia), Schizophrenia and Affective Disorder. Results indicated that while both psychopathic groups (Mixed and Personality Disorder) showed high scores on almost all RSAP items, the Affective Disorder group showed low scores on almost all items. Results of a discriminant function analysis indicated that Hare's RSAP was superior to the MMPI measures at discriminating between psychopaths and non-psychopaths. Use of the discriminant function to re-allocate patients to criterion groups showed a high hit rate (94%) for psychopathic patients but a hit rate of only 61% for non-psychopathic patients. Half of the schizophrenic patients were mis-allocated to the psychopathic group. The results support the idea of an affective deficit common to psychopaths and schizophrenics, but suggest that psychopaths additionally show a deficit which may be characterized by a lack of goal-directed behaviour.     

SEX DIFFERENCES IN THE ATTRIBUTION OF SOCIALLY DESIRABLE AND UNDESIRABLE TRAITS TO OUT-GROUP MEMBERS*

One hundred and forty-four male and female Australian subjects rated an Australian or a Vietnamese target group on the possession of five socially desirable and five socially undesirable personality traits. As predicted, the out-group was perceived less favourably than the in-group, but only by the males, the females not making the distinction.