Observing responses in rats: Support for the secondary reinforcement hypothesis

Rats' lever presses on a retractable lever earned brief presentations of discriminative stimuli signalling periods in which responding on an alternative lever was either non-reinforced (extinction) or reinforced on a random ratio schedule. The predictions of two theoretical accounts of this behaviour were tested by studying the effects of omitting either the stimulus signalling the reinforced or that signalling the non-reinforced schedule component. Under these conditions rats' behaviour is determined by the conditioned, affective properties of the stimuli rather than by their purely informational properties.     

Reducing STD/HIV Stigmatizing Attitudes Through Community Popular Opinion Leaders in Chinese Markets

Reducing STDs and HIV/AIDS incidence requires campaigns designed to change knowledge, attitudes, and practices of risky sexual behavior. In China, a significant obstacle to such changes is the stigma associated with these diseases. Thus 1 campaign intervention strategy is to train credible community leaders to discuss these issues in everyday social venues. This study tested the effectiveness of such an approach on reducing HIV/AIDS stigma, across 2 years, from a sample of over 4,500 market vendors, in 3 conditions. Results showed an increasing growth in market communication about intervention messages, and concomitant declines in stigmatizing attitudes, across time, with the greatest changes in community popular opinion leaders, significant changes in intervention nonopinion leaders, and little change in the control markets.     

Persistent alterations in biological profiles in women with abuse histories: influence of premenstrual dysphoric disorder.

OBJECTIVE: To examine dysregulation in biological measures associated with histories of abuse in women and whether women with premenstrual dysphoric disorder (PMDD) differ in their dysregulation. DESIGN: Twenty-five women meeting prospective criteria for PMDD and 42 non-PMDD controls underwent structured interview to determine abuse histories and lifetime Axis I diagnoses, excluding those with current Axis I disorders or using medications. MAJOR OUTCOME MEASURES: Plasma cortisol and norepinephrine (NE), heart rate (HR), blood pressure (BP), and vascular resistance index (VRI) were assessed at rest and in response to mental stress. RESULTS: A greater proportion of PMDD women had prior abuse compared with non-PMDD women. Regardless of PMDD status, all abused women had lower plasma NE and higher HRs and tended to have lower plasma cortisol at rest and during stress. Abused women also reported more severe daily emotional and physical symptoms. Greater VRI and BP at rest and during stress were seen only in PMDD women with abuse. CONCLUSION: There is persistent dysregulation in stress-responsive systems in all abused women that cannot be accounted for by current psychiatric illness or medications, and PMDD women may be differentially more vulnerable to the impact of abuse on measures reflecting alpha-adrenergic receptor function.     

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.     

Terror Management and Personality: Variations in the Psychological Defense Against the Awareness of Mortality

Drawing on terror management theory (TMT), we discuss the psychological motivations that shape personality at two levels: the characteristically human personality common to us all and the individual differences that distinguish some people from others. TMT posits that the motivation to protect the self against deep-rooted fears about mortality drives people to maintain meaningful, reliable conceptions of reality and positive evaluations of themselves, two broad tendencies that form the foundation of every person’s personality. We review studies showing that mortality reminders increase efforts to bolster cultural sources of meaning and self-esteem in similar ways across individuals and cultures. TMT also posits that individual differences in personality partly reflect the different sources of meaning and self-esteem that people invest in to assuage mortality fears. We review evidence that individual differences predict the degree and direction of people’s defensive responses to mortality reminders. Directions for future research are discussed.     

FACTORS THAT INFLUENCE DEPRESSIVE SYMPTOMS IN MOTHERS OF INFANT

This study explored the association between interpersonal factors and depressive symptoms in first-time mothers over the first two years of parenthood. An interpersonal style characterized by dependency, recollections of rejection in childhood, and current relationship characteristics was assessed in a nonclinical sample of 133 women. The final model explained 52% of the variance in depressive symptoms at 24 months. Controlling for initial symptom levels, interpersonal variables explained 24% of the outcome variance. The findings suggest that two interpersonal attributes, peer rejection in childhood and a dependent interpersonal style, are particularly important to our understanding of depressive symptomatology.     

Gaining knowledge via other minds: Children's flexible trust in others as sources of information

In five experiments, we examined 3‐ to 6‐year‐olds’ understanding that they could gain knowledge indirectly from someone who had seen something they had not. Consistent with previous research, children judged that an informant, who had seen inside a box, knew its contents. Similarly, when an informant marked a picture to indicate her suggestion as to the content of the box, 3‐ to 4‐year‐olds trusted this more frequently when the informant had seen inside the box than when she had not. Going beyond previous research, 3‐ to 4‐year‐olds were also sensitive to informants’ relevant experience when they had to look over a barrier to see the marked picture, or ask for the barrier to be raised. Yet when children had to elicit the informant's suggestion, rather than just consult a suggestion already present, even 4‐ to 5‐year‐olds were no more likely to do so when the informant had seen the box's content than when she had not, and no more likely to trust the well‐informed suggestion than the uninformed one. We conclude that young children who can ask questions may not yet fully understand the process by which they can gain accurate information from someone who has the experience they lack.