No Evidence of Suicide Increase Following Terrorist Attacks in the United States: An Interrupted Time‐Series Analysis of September 11 and Oklahoma City

There is substantial evidence of detrimental psychological sequelae following disasters, including terrorist attacks. The effect of these events on extreme responses such as suicide, however, is unclear. We tested competing hypotheses about such effects by employing autoregressive integrated moving average techniques to model the impact of September 11 and the Oklahoma City bombing on monthly suicide counts at the local, state, and national level. Unlike prior studies that provided conflicting evidence, rigorous time series techniques revealed no support for an increase or decrease in suicides following these events. We conclude that while terrorist attacks produce subsequent psychological morbidity and may affect self and collective efficacy well beyond their immediate impact, these effects are not strong enough to influence levels of suicide mortality.     

Binocular cues in the perception of distance of a point source of light

The ability to make egocentric distance estimates of a single point source of light, seen in darkness and without the cues of changing size and luminance, was investigated in sixteen observers. The attenuation required to maintain constant luminance, when the target was viewed from different distances, was shown to follow the inverse square law providing the angle subtended by the light was less than 20 s arc. Distance changes were also simulated by means of a split mirror which produced vergence cues, or by test lenses to provide accommodation cues. Over the range 0.5 to 9.2 m distance estimates were surprisingly accurate, although there was some overestimation of near and underestimation of far distances. Most observers made good judgements when only convergence cues were varied, whereas no observers made consistently good judgements when only accommodation cues were varied. The difficulties are discussed in terms of the accommodation-convergence link. When distance was simulated by changing convergence and accommodation cues, estimates were not as good as when real distance was changed. Since good estimates were made with brief target exposures, these judgements were not based on subsequent convergence or accommodation changes. It is suggested that the metric or reference against which the apparently absolute judgements were made was the efferent demand signal associated with a 'resting' position of convergence in darkness.     

Predicting diagnosis performance with measures of cognitive style

This study examines the relationship between performance on a context-independent fault diagnosis task and two dimensions of cognitive style: field dependence/independence (D-I) and focusing/scanning (F-S). The effects on diagnosis performance of training and the ability of both dimensions of style jointly to predict fault-finding ability were considered. The results showed that field independents and focusers were superior fault diagnosticians. Training, in the form of verbal feedback messages, was uniformly effective for the D-I dimension although field independents maintained a superior level of performance, over field dependents. In general, for the F-S dimension, training had little effect on either the focusers or scanners. A combination of scores on the F-S and D-I dimensions significantly enhanced the proportion of the variance in testing efficiency that could be accounted for during fault-finding. Finally it is argued that the F-S and D-I dimensions should be recognized as measures of ability, not style. Future research should be directed at identifying between subject differences on fault diagnosis tasks with reference to theories of information processing.     

On estimating processing variance: commentary and reanalysis of Kail's "Developmental functions for speeds of cognitive processes".

A recent paper by Kail (1988) in this journal appears to contain a significant error in the data analysis. The "goodness-of-fit" coefficients reported which suggest that overall about 94% of the variance can be accounted for by the model seem to be a substantial overestimation as a result of inappropriate procedures for statistical modeling. Using the data made available to us by Kail, we have reanalyzed these results. The corrected values range from 0.9 to 92.1% for the individual tasks with an overall average between 40 and 60%. We suggest that the support for the original conclusions is considerably weaker than reported.     

Cardiovascular reactivity and interpersonal influence: active coping in a social context

Previous studies have demonstrated that effortful attempts to secure positive outcomes or avoid negative outcomes produce significant increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR). Although these effects of active coping on cardiovascular reactivity are central in current psychosomatic theories, virtually all of the research to date has used impersonal, asocial tasks. Our two studies examined the cardiovascular effects of effortful attempts to influence other people. In Study 1, male subjects attempting to influence the opinions of their discussion partner to improve their own chances of winning money displayed significantly greater SBP, DBP, and HR reactivity. In Study 2, we obtained similar effects on SBP and DBP reactivity in men and women, while both preparing an influence attempt and making that attempt. Furthermore, reactivity levels were larger as the magnitude of incentive for successful persuasion increased. Implications of this interpersonal equivalent of active coping for the development of cardiovascular disease are discussed.     

Predicting Contraceptive Efficacy: A Discriminant Analysis of Three Groups of Adolescent Women1

The relationship of knowledge and attitudes to adolescent contraceptive efficacy was investigated in a multivariate study, with demographic and sexual history variables covaried. Subjects were unmarried, sexually active 15- to 19-year-old women. Two studies were conducted: one using a large and representative sample and the second using a smaller, high socioeconomic status sample that is more typical of samples generally used in earlier research. Subjects were classified as effective, ineffective, or nonusers of contraception, based on both frequency of use and effectiveness of the method(s) they used. Two discriminant function analyses were performed to determine (a) whether knowledge and attitudes contributed to discrimination among the groups over and above discrimination attributable to demographic and sexual history variables, and (b) which variables distinguished ineffective users from both other groups. The results of both studies indicate that attitudes, particularly attitudes toward contraception, are strong predictors of patterns of contraceptive use. Ineffective users were distinguished from nonusers by their greater knowledge of contraception, and from both other groups by their greater sexual activity and more positive attitudes toward intercourse. The discussion focuses on the theoretical implications of the results, the usefulness of the effective/ineffective/nonuser categorization, and applications of these findings to design of interventions.     

An assessment of decision-making as a possible factor in the age-related loss of contrast sensitivity

The possibility that changes in decision-making may contribute to the age-related decline in contrast sensitivity has been investigated in nineteen young subjects (ages 21-38 years) and twenty-seven old subjects (ages 55-92 years). A signal detection paradigm was employed in which the detection of stationary sinusoidal grating patterns was measured at 3 and 15 cycles deg-1 for a range of contrasts which were psychophysically equivalent for each subject. A decline in contrast sensitivity with age at the spatial frequencies studied was confirmed for contrast thresholds obtained both by the ascending method and from the 50% hit rate for detection of the grating pattern. The criterion adopted for decision-making, expressed as both beta and percentage bias, did not change significantly between young and old subjects at 15 cycles deg-1. At 3 cycles deg-1, criterion beta did not change significantly at X0.8, X1.0, or X1.2 contrast threshold, but at contrast giving 50% hit rate there was a significant increase with age. The percentage bias increased significantly at contrast threshold but not at 50% hit rate. It is inferred from the results that the loss of contrast sensitivity was not accountable in terms of the adoption of a more conservative criterion by older subjects. Hence visual loss in ageing is attributed to changes within the visual pathway rather than within higher decision-making centres.     

Family crisis intervention: fish or fowl?

This paper considers the status of family intervention as an area of interest defined by its literature (70 publications) and includes a brief history, assessment of present status, and recommendations for future development of family crisis intervention as a distinct field with concepts and goals that can be clearly defined, taught, researched, and repeated in treatment. Recommendations are made for the development of an explicit paradigm for intervention with a clear, common language of terms and concepts for family involvement. Suggested directions for developing the paradigm and language are explored.     

Do letter features migrate? A note of caution

Summary The feature-integration model of visual information processing (Treisman & Gelade, 1980) predicts perceptual errors based on the incorrect grouping of stimulus features in multi-element displays. Experiment 1 examined the frequency of such errors with a tachistoscopic bar probe task using letters and novel patterns with a production response. A substantial proportion of the errors did involve figures that were not present in the display but contained combinations of features which had been present. Such errors were especially prominent with novel patterns. The results with letters suggested that such responses were due to guessing, not feature migration, and this was confirmed by Experiment 2. In the second study, responses were collected for single character displays but were scored as if they had been responses to the multielement displays in Experiment 1. The results showed the same high proportion of illusory conjunction errors as the previous results and it was concluded that both results were due to guessing. Spatial confusions in the bar probe task with letters appear to involve whole characters, not character features.This research was supported by grant A-9581 from the National Science and Engineering Council of Canada to the senior author. This research was reported as a paper to the annual meeting of the Canadian Psychological Association, Toronto, 1981. Ian Morrison is now a post-doctoral fellow at the Department of Psychology, Carnegie-Mellon University.