Sensitivity to reinforcement in concurrent arithmetic and exponential schedules

The generalized matching law states that the logarithm of the ratio of responses emitted or time spent responding in concurrent variable-interval schedules is a linear function of the logarithm of the ratio of reinforcements obtained. The slope of this relation, sensitivity to reinforcement, varies about 1.0 but has been shown to be different when obtained in different laboratories. The present paper analyzed the results from 18 experiments on concurrent variable-interval schedule performance and showed that response-allocation sensitivity to reinforcement was significantly smaller when arithmetic, rather than exponential, progressions were used to produce variable-interval schedules. There were no differences in time-allocation sensitivity between the two methods of constructing variable-interval schedules. Since the two laboratories have consistently used different methods for constructing variable-interval schedules, the differences in obtained sensitivities to reinforcement are explained. The reanalysis suggests that animals may be sensitive to differences in the distribution of reinforcements in time.     

Sex differences in spatial ability and spatial activities

Explanations of sex-related differences in spatial ability emphasizing the role of sex-differentiated experience have not been supported by direct measurement of spatial activities during adolescence, the period when these differences seem to increase. The present research involved development of a scale to measure the spatial experience of adolescents and adults. In Study 1, a list, as complete as possible of adolescent activities was compiled and given to undergraduate judges for ratings of involvement of spatial skills and sex-typing. Judges also indicated whether they had participated in each activity. Activities considered spatial by 75% or more of the judges were used to develop a spatial experience questionnaire. Judgments of the spatial nature of tasks were positively correlated with judged masculinity and with greater male than female participation. In Study 2, participation in spatial activities by undergraduates was correlated with spatial ability as measured by the Differential Aptitude Test. The activity questionnaire should prove useful in studying the development of spatial ability in adolescents and adults.     

A Risk-Amplification Model of Victimization and Depressive Symptoms Among Runaway and Homeless Adolescents

This report is an examination of a theoretical model of risk amplification within a sample of 255 homeless and runaway adolescents. The young people were interviewed on the streets and in shelters in urban centers of four Midwestern states. Separate models were examined for males (n = 102) and females (n = 153). Results indicated that street experiences such as affiliation with deviant peers, deviant subsistence strategies, risky sexual behaviors, and drug and/or alcohol use amplified the effects of early family abuse on victimization and depressive symptoms for young women. These street adaptations significantly increased the likelihood of serious victimization over and above the effects of early family history for both young men and women. Similarly, street behaviors and experiences increased the likelihood of depressive symptoms for young women over the effects of early family abuse, but not for young men. The risk-amplification model from the life course theoretical perspective is discussed as an example of the cumulative continuity of maladaptive behaviors.     

运动强度和持续时间对运动后过量氧耗的影响

本研究采用双因素实验设计探讨了运动负荷强度和持续时间对 E-POC的影响。实验结果发现 ,运动过程中机体净耗氧量主要取决于运动持续时间 ,而运动后的 EPOC既受运动强度 ,也受持续时间的影响 ,但以前者的作用更加明显 ;运动后 VO2 的恢复速度快于血乳酸的消除 ,不同运动条件下的氧亏量变化主要取决于运动负荷的强度。     

Aptness predicts preference for metaphors or similes, as well as recall bias

Why might we sometimes prefer a metaphor such as “genes are blueprints” to a simile such as “genes are like blueprints”? One possibility is that metaphors are preferred when the comparison between a tenor (e.g., genes) and a vehicle (e.g., blueprints) seems especially apt. That is, metaphors might be used when the comparison captures many salient features of the tenor in question. The present experiments examined the relation between the aptness of comparisons and people’s preferences for expressing those comparisons as metaphors or as similes. In Experiment 1, it was found that there is consensus on how to express particular comparisons. In Experiment 2, it was found that this preference can be predicted from the aptness of a comparison. It was also found that aptness can predict errors in the recall of comparisons. These findings have implications for theories of metaphor.     

Monthly fluctuation in task concentration in female college students.

50 university women with consistent and rhythmic menstrual cycles were given Golden's version of the Stroop color-word test to evaluate their concentration accuracy. 50 male undergraduates were also tested as a control sample. The participants took the Stroop test every seven days for four consecutive weeks to allow examination of whether change in the color and word naming activity occurred. A split-plot analysis of the variance of the scores gave a significant difference for the sequence in which the tests were taken, the measures recited during the testing, and the sex of the respondent. When the values for the women were ordered to correspond to stages of their menstrual cycle, the over-all mean accuracy rose slowly to midcycle, then dropped as menses approached. This supports the hypothesis that the women's concentration was at the lowest level during the latter part of the monthly cycle. Women scored significantly higher on the color and word naming task on the Stroop test than men.     

Psychosocial predictors of gay men's AIDS risk-reduction behavior.

Used psychosocial variables derived from the health belief model (Rosenstock, 1974), Bandura's (1986) self-efficacy framework, and protection motivation theory (Rogers, 1984) to predict self-reported AIDS risk-reduction behaviors in a sample of 389 homosexual men who participated in the Multicenter AIDS Cohort Study in Los Angeles and who knew their HIV antibody status. Hierarchical multiple regression analyses showed that self-efficacy, perceived risk, response efficacy, and prior sexual behavior accounted for approximately 70% of the variance in the total number of sexual partners and the number of anonymous partners over a 6-month interval, controlling for demographic variables, HIV antibody status, and presence of a primary partner. A logistic regression analysis showed that barriers to change predicted increased unprotected anal receptive intercourse over a 6-month interval, controlling for prior behavior. The relation of health beliefs to risk-reduction behavior was substantially different for HIV-seropositive men without primary partners than for other groups of gay men. Implications for interventions are discussed.     

The Field of Disasters and Disaster Stress

The literature on disasters - including the contributions to the present symposium - refers to a wide range of victim groups and very different kinds of disasters. There is a need for a classificatory system which draws the different studies together. Disasters may be natural, technological or human, and can be subdivided into categories relating to earth, fire, water/liquid and people. The stages in dealing with disaster include preparedness, response, recovery and mitigation. Further categorisation is necessary in terms of types of victim. A three-dimensional model for the integration of disaster studies is proposed.