Attentionally splitting the mass distribution of hand-held rods

Two experiments on the length-perception capabilities of effortful or dynamic touch differed only in terms of what the subject intended to perceive, while experimental conditions and apparatus were held constant. In each trial, a visually occluded rod was held as still as possible by the subject at an intermediate position. For two thirds of the trials, a weight was attached to the rod above or below the hand. In Experiment 1, in which the subject's task was to perceive the distance reachable with the portion of the rod forward of the hand, perceived extent was a function of the first moment of the mass distribution associated with the forward portion of the rod, and indifferent to the first moment of the entire rod. In Experiment 2, in which the task was to perceive the distance reachable with the entire rod if it was held at an end, the pattern of results was reversed. These results indicate the capability of selective sensitivity to different aspects of a hand-held object's mass distribution, without the possibility of differential exploration specific to these two tasks. Results are discussed in relation to possible roles of differential information, intention, and self-organization in the explanations of selective perceptual abilities.     

A new typology of health behaviours for personality-health predictions: The case of locus of control

Psychological investigations of the impact of personality on health behaviours have tended to emphasize fine distinctions among personality variables while failing to distinguish among different kinds of behaviours. For example, theoretical treatments of perceived personal control are quite sophisticated; in contrast, only one well-known analysis of health behaviours exists. We propose four categories of health-enhancing behaviours, which take into account contemporary views of the shift in health care from acute and physician-directed actions to long-term and patient-directed efforts. In addition, we suggest that perceived control (we emphasize locus of control because of its generality and parsimony) is an important predictor variable when combined with other factors common to current models of health behaviour.     

Conditioned approach and withdrawal behavior in pigeons: Effects of a novel extraneous stimulus during acquisition and extinction

Three experiments examined the effects of complete removal of reinforcement and of the introduction of a novel stimulus on conditioned approach and withdrawal behavior exhibited by pigeons in an autoshaping paradigm. Experiment 1 indicated that complete omission of food from the experimental situation resulted in the gradual disappearance of both approach and withdrawal behavior in subjects that had received either explicitly paired or explicitly unpaired conditioning. Subsequent presentation of a novel visual stimulus reinstated both approach and withdrawal. Experiment 2 replicated these findings in a within-subjects, discriminative paradigm. In Experiment 3, presenting the novel visual stimulus during acquisition when approach and withdrawal behaviors were asymptotic did not produce significant disruption of performance. These data suggest that removal of reinforcement leads to the disappearance of withdrawal as well as approach performance, and that subsequent presentation of a novel stimulys reinstates whatever behavior was dominant prior to extinction—a finding that seems analogous to results of experiments concerning proactive interference.     

Psychometric and instructional validation approaches in the hierarchical sequencing of learning tasks

Two strategies used to test prerequisite relationships among intellectual skills were employed to examine the sequence of three types of subtraction tasks. A psychometric validation strategy yielded results similar to an instructional validation strategy. This finding provides support for the use of the more efficient psychometric approach for validating large numbers of learning hierarchies in relatively short periods of time.     

Prediction of success or failure in birth planning: An approach to prevention of individual and family stress

Following the view that individual future time perspective is an outcome of the socialization process, it was hypothesized that good contraceptors would display significantly longer future time extension than poor contraceptors. In a Planned Parenthood agency, 25 subjects from each group, constituting nearly the whole clinic population in these categories for a 3-month period, were given the Future Events Test during their clinic visits. The major hypothesis was confirmed, and also a significant tendency towards viewing future events more negatively was found among the poor contraceptors. Demographic data did not discriminate clearly between the two groups, though the poor contraceptors were somewhat younger and had a somewhat higher weekly family income. Use of personality variables in predicting birth-planning success or failure seems more promising than continued reliance solely on the sociocultural approach. Implications for screening and prevention in the interest of the individual, the family, and the community are discussed.     

Book reviews

Wyer, Robert S., Jr. Cognitive Organization and Change : an Information Processing Approach. Potomac, Maryland: Lawrence Erlbaum Associates. 1974. Pp. 502. £10.50.

Egan, J. P. Signal Detection Theory and ROC Analysis. New York: Academic Press. 1975. Pp. 277. £9.75. ISBN

Aldis, O. Play-Fighting. New York: Academic Press. 1975. Pp. 319. £8.75.

Warburton, D. M. Brain Behaviour and Drugs. London: John Wiley. 1975. Pp. 280. £6.95. ISBN 0471 91991 8.

Grieve, D. W., Miller, D., Mitchelson, D., Paul, J. and Smith, A. J. Techniques for the Analysis of Human Movement. London: Lepus Books. 1975. Pp. 177. £5.50.     

A quasi-experimental investigation of message appeal variations on organ donor registration rates.

OBJECTIVE: Approximately 6,000 Americans die every year awaiting an organ transplant. Health promotion interventions may alleviate the shortage of viable organs by increasing the number of registered organ donors. This study is the first to evaluate the differential effectiveness of various organ donor messages in naturalistic settings. DESIGN: A 4 (Appeal)x4 (Exemplar)x4 (Location) counterbalanced quasi-experimental design was implemented. MAIN OUTCOME MEASURE: The behavioral outcome measure was the number of individuals who registered to be organ donors at computer kiosks. RESULTS: A number of significant main effects and interactions emerged. Most notably, of the 4 different appeals (counterargument, emotional, motivating action, dissonance), counterargument was by far the most efficacious, especially in academic-type settings (library, university, community college); the emotional appeal was most successful in hospitals. CONCLUSIONS: The findings from this study have implications for both organ donor investigations and health campaign research in general. Statistical interactions highlight the importance of evaluating multiple exemplars in multiple locations for each type of appeal when conducting health campaign research.