The insistence of vision: Why do people look at a salient stimulus when it signals target absence?

Researchers and practitioners across many fields would benefit from the ability to predict human search time in complex visual displays. However, a missing element in our ability to predict search time is our ability to quantify the exogenous attraction of visual objects in terms of their impact on search time. The current work represents an initial step in this direction. We present two experiments using a quadrant search task to investigate how exogenous and endogenous factors influence human visual search. In Experiment 1, we measure the oculomotor capture—or the tendency of a stimulus to elicit a saccade—of a salient quadrant under conditions in which the salient quadrant does not predict target location. Despite the irrelevance of quadrant salience, we find that subjects persist in making saccades towards the salient quadrant at above-chance levels. We then present a Bayesian-based ideal performer model that predicts search time and oculomotor capture when the salient quadrant never contains the search target. Experiment 2 tested the predictions of the ideal performer model and revealed human performance to be in close correspondence with the model. We conclude that, in our speeded search task, the influence of an exogenous attractor on saccades can be quantified in terms of search time costs and, when these costs are considered, both search time and search behaviour reflect a boundedly optimal adaptation to the cost structure of the environment.     

A psychological predictor of elders' driving performance: social‐comparisons on the road

Older individuals often believe they can drive better than their contemporaries. This belief is an example of downward social‐comparisons; they can be self‐enhancing tools that lead to beneficial outcomes. As predicted, we found that drivers who engaged in downward social‐comparisons were significantly less likely to have adverse driving events over time, after controlling for relevant factors (p = .02). This effect was particularly strong among women, who tend to experience more negative driving stereotypes (p = .01). The study was based on 897 interviews of 117 elder drivers, aged 70–89 years, over 2 years. Our findings suggest that interventions to reduce adverse driving events among elders could benefit from including a psychological component.     

Stimulus exposure effects in human associative learning

Learning that one cue (CS) predicts a second, salient cue (US) can often be slowed by prior exposure to one or both stimuli. In animals, CS-US learning is more strongly retarded following uncorrelated exposure to both CS and US than following exposure to the US alone. In this paper we present several studies showing a similar effect in humans, using a computer-based task. Experiments 1 and 2 used a between-groups design and demonstrated a strong CS/US exposure effect, whether or not the US was signalled by a neutral cue during exposure. Experiment 3 demonstrated similar effects using a within-subjects design. Overall, these results are consistent with several theoretical interpretations and suggest that uncorrelated CS/US exposure leads to a robust retardation of subsequent CS-US learning in humans.     

Intervention Induced Changes in Perceptions of Parenting and Risk Opportunities Among Rural African American

A randomized prevention trial was conducted contrasting families who took part in the Strong African American Families Program (SAAF), a preventive intervention for rural African American parents and their 11-year-olds, with control families. The trial, which included 671 families, indicated that intervention-induced changes occurred in intervention-targeted parenting and youth behavior, as well as youth initiation of alcohol use and sexual activity. Four waves of data collected were obtained at pretest, 3-month post-test, 29 month long-term follow up; and 65 month long-term follow up. Three data points were selected and analyzed in the current study: pretest, post-test, and 65 month long-term follow up to capture the sustainability of SAAF during three critical developmental stages—middle childhood, early adolescence, and late adolescence. Intervention-induced changes in parenting mediated the effect of intervention-group influences on changes in the onset and escalation of alcohol use and sexual activity over 65 months through its positive influence on youths’ perceptions and internalization of parental norms and resistance to engaging in risk opportunities. These findings highlight the potential for family-based prevention programs to enhance positive developmental outcomes to reduce HIV-related risk behaviors among rural African American youth.     

Book reviews

Jacknedoff, R. (1985). Semantics and cognition. Cambridge, MA: The MIT Press, Pp. 283. ISBN 0-262-60013-7. £ 9.95.

Lakoff, g. (1987). Women, fire and dangerous things : What categories reveal about the mind. Chicago, IL.: Chicago University Press. Pp. 624. ISBN 0-266-46803-8. £19.95.

Longuet-Higgins, H. C. (1987). Mental processes : Studies in cognitive science. Cambridge, MA: The MIT Press. Pp. 424. ISBN 0-262-12119-0. £22.50.

Nowakowska, M. (1986). Cognitive sciences: Basic problems, new perspectives, and implications for artificial intelligence. Orlando, FL: Academic Press. Pp. 379. ISBN 0-12-522620-9. £44.50.

Winograd, T. & Flores, F. (1986). Understanding computers and cognition: A new foundation for design. Norwood, NJ: Ablex. Pp. 207. ISBN 0-89391-050-3. £23.

Weisberg, R. W. (1986). Creativity: Genius and other myths. New York:W. H.Freeman and company. Pp. 169. ISBN 0-1767-1769-7. £9.95.

Bosshardt, H. R. S. G (1986). Perspektiven auf Sprache. Berlin : Walter de Gruyter. Pp. 326. ISBN 3-11-010068-1. DM134.00.     

Impact of caffeine and psychological stress on blood pressure in black and white men

The purpose of this study was to examine the effects of caffeine and psychological stress on systolic blood pressure (SBP) and heart rate (HR) in 40 healthy Black and White male regular coffee drinkers. Half the subjects had a positive family history of hypertension (FH+), and half did not. The effects of 250 mg of caffeine versus placebo (3 mg) in decaffeinated coffee were compared in a within-subject, double-blind, cross-over design. SBP and HR were measured at rest, after caffeine ingestion, during mental arithmetic stress, and during recovery. Results confirmed previous findings with White men that a moderate dose of caffeine produced significant increases in SBP and little effect on HR and that the pressor effects of caffeine and stress combined additively. Contrary to expectations, no overall race or family history differences in SBP levels or in SBP reactivity were observed. FH+ Blacks, however, evidenced slower SBP recovery than Whites. Whites evidenced higher overall HR levels than blacks, but this difference was not specific to caffeine or to mental stress. Mechanisms of racial differences in reactivity underlying differential risk for hypertension are discussed, as well as the utility of caffeine as a pharmacologic probe for such differences.