Overt activity during conditioned suppression: a search for punishment artifacts

Pigeons, previously trained to peck a key (using food as the reinforcer), were permitted unlimited access to food and, concurrently, key pecking was allowed to go unreinforced until all pecking ceased. A tone ending with electrical shock was then repeatedly presented in an effort to establish the tone as a potentially suppressing stimulus. When key pecking was later reestablished, tone presentation (without shock) sharply reduced the rate of pecks. At selected points throughout the experiment, special observation procedures supplemented the recordings of key pecks and provided detailed fine-grain protocols of the birds' overt movements during the periods before, during, and after tone presentations. Results indicated that neither punishment of key pecks nor punishment of other overt movements was a necessary precursor to the conditioned suppression observed in the final stage. As such, the findings support interpretations of conditioned suppression that characterize the phenomenon as reflecting a conditioned emotional reaction that either directly or indirectly inhibits overt activity.     

Category dimensionality and feature knowledge: when more features are learned as easily as fewer

Three experiments compared the learning of lower-dimensional family resemblance categories (4 dimensions) with the learning of higher-dimensional ones (8 dimensions). Category-learning models incorporating error-driven learning, hypothesis testing, or limited capacity attention predict that additional dimensions should either increase learning difficulty or decrease learning of individual features. Contrary to these predictions, the experiments showed no slower learning of high-dimensional categories; instead, subjects learned more features from high-dimensional categories than from low-dimensional categories. This result obtained both in standard learning with feedback and in noncontingent, observational learning. These results show that rather than interfering with learning, categories with more dimensions cause individuals to learn more. The authors contrast the learning of family resemblance categories with learning in classical conditioning and probability learning paradigms, in which competition among features is well documented.     

The role of small changes in the acoustic environment in modifying the startle reflex.

When either the intensity or frequency spectrum of an approximately 70-db. SPL narrow-band noise was abruptly changed by a small amount, the rat's response to a startle stimulus presented 64 msec later was inhibited. When similar small frequency changes preceded the startle stimulus by ony 5 msec, the latency of the startle response was reduced, but even relatively large changes in intensity of the antecedent stimulus had no effect on response latency. These findings provide added support for the generalization that the neural processes associated with startle are engaged by small changes in the auditory environment. They also point to a measure of separation between the processes responsible for inhibition and those responsible for latency shift.     

Stigma and Ostracism Associated with HIV/AIDS: Children Carrying the Secret of Their Mothers' HIV+ Serostatus

Qualitative interviews were conducted with mothers (N = 47) who had disclosed their HIV status to their children. The majority of mothers explicitly told their child not to disclose to other people that she was HIV-positive because they feared repercussions in the way of stigma and ostracism for both themselves and their child. Approximately one-fourth of the mothers identified safe people, to whom their child could discuss her serostatus, such as family members, health care providers, or therapists. The majority of the children respected their mothers' wishes; only four children disclosed to someone after being explicitly told not to do so. A significant number of children expressed concerns about their friends finding out, fearing that they would be ostracized or that it would be assumed they were also infected. In addition, the children did not want others to find out because they wanted to protect their mothers. The burden of keeping the secret of their mothers' serostatus does seem to be a stressor for some of the children.     

Attention to faces: a change-blindness study

What strategies does human vision use to attend to faces and their features? How are such strategies altered by 2-D inversion or photographic negation? We report two experiments in which these questions were studied with the flicker task of the change-blindness literature. In experiment 1 we studied detection of configural changes to the eyes or mouth, and found that upright faces receive more efficient attention than inverted faces, and that faces shown with normal contrast receive more efficient attention than faces shown in photographic negative. Moreover, eyes receive greater attention than the mouth. In experiment 2 we studied detection of local changes to the eyes or mouth, and found the same results. It is well known that inversion and negation impair the perception and recognition of faces. The experiments presented here extend previous findings by showing that inversion and negation also impair attention to faces.     

Are the discrepancies between self- and others' appraisals of competence predictive or reflective of depressive symptoms in children and adolescents: a longitudinal study, Part II

Two cohorts of children and adolescents (who started 6th grade in 1993 and 1996), parents, teachers, and peers participated in a 4-wave, 2-year, longitudinal study of perceived competence and depressive symptoms. The authors assessed children's tendencies to underestimate their competence (discrepant self-appraisals) relative to the appraisals of significant others. We also assessed the degree to which self-appraisals reflected the evaluations of others (reflective self-appraisals). Domains of competence were academic competence, physical appearance, behavioral conduct, social acceptance, and athletic competence. Cross-sectional analyses indicated that depressive symptoms correlated with reflective and discrepant self-appraisals. Longitudinal analyses revealed that reflective and discrepant self-appraisals predicted subsequent depressive symptoms and that depressive symptoms predicted discrepant but not reflective self-appraisals. Clinical implications of the findings are discussed.