Different recognition cues reveal the decision rules used for egg rejection by hosts of a variably mimetic avian brood parasite

Brood parasitism imposes several fitness costs on the host species. To reduce these costs, hosts of avian brood parasites have evolved various defenses, of which egg rejection is the most prevalent. In the face of variable host-parasite mimicry and the costs of egg discrimination itself, many hosts reject only some foreign eggs. Here, we experimentally varied the recognition cues to study the underlying cognitive mechanisms used by the Chalk-browed Mockingbird (Mimus saturninus) to reject the white immaculate eggs laid by the parasitic Shiny Cowbird (Molothrus bonariensis). Immaculate eggs are the only parasite eggs rejected by this host, as it accepts all polymorphic, spotted eggs laid by cowbirds. Using a within-breeding pair experimental design, we tested for the salience of spotting, UV reflectance, and brightness in eliciting rejection. We found that the presence of spotting significantly decreased the probability of rejection while increments in brightness significantly increased rejection frequencies. The cognitive rules underlying mockingbird rejection behavior can be explained by a decision-making model which predicts changes in the levels of rejection in direct relation to the number of relevant attributes shared between host and parasite eggs.     

The effects of young children's affiliations with prosocial peers on subsequent emotionality in peer interactions

Preschoolers’ (60 boys and 64 girls, M age = 50.73 months) affiliations with prosocial peers were observed in naturally occurring interactions and then examined in relation to positive and negative emotionality within their peer interactions one semester later. Greater affiliation with prosocial peers in the fall was related to enhanced positive emotionality (especially for girls) and decreased negative emotionality (especially for boys) in later peer interactions. These findings held when initial levels of the emotion were controlled and were found above and beyond variations in classroom levels of prosociality. The findings suggest that peers exert influence in early childhood and that these effects can positively affect the quality of young children's later peer interactions.     

The missing link between faces and names: Evidence from Alzheimer's disease patients

Retrieval of proper names is a cause of concern and complaint among elderly adults and it is an early symptom of patients suffering from neurodegenerative diseases such as Alzheimer's disease (AD). While it is well established that AD patients have deficits of proper name retrieval, the nature of such impairment is not yet fully understood. Specifically, it is unknown whether this deficit is due to a degradation of the links between faces and proper names, or due to deficits in intentionally accessing and retrieving proper names from faces. Here, we aim to investigate the integrity of the links between famous faces and proper names in AD while minimizing the impact of the explicit retrieval. We compare the performances of AD patients and elderly controls in a face-name priming task. We assess the integrity of the link between faces and names at two different levels: identity level - the name and face belong to the same person; and semantic level - the name and face belong to the same category (e.g., politicians). Our results reveal that AD patients compared with controls show intact semantic priming but reduced priming for person identity. This suggests that the deficits in intentionally retrieving proper names in AD are the result of a partial disruption of the network at the identity level, i.e., the links between known faces and proper names.     

UNDERSTANDING THE SEXUALITY OF MEXICAN-BORN WOMEN AND THEIR RISK FOR HIV/AIDS

Participants in this study were 300 Mexican women of rural origin who were born and raised in villages of that country and who belong to one of three groups: married and living with their husbands in Los Angeles, California ( n = 100), married to migrant workers but living in Mexico ( n = 100), and living in Mexico with their spouses ( n = 100). Trained female professionals conducted face-to-face interviews in Spanish, in Mexico and in the United States. The purpose of this study was to identify specific sexual practices, coping strategies in sex-related situations, and fears and concerns regarding sexual intercourse. This article analyzes how these elements place Mexican ruralorigin women at risk for HIV/AIDS. It discusses the need to design intervention strategies to prevent HIV/AIDS that take into consideration the limited power of women in traditional societies and the cultural precepts that promote gender roles characterized by male dominance and female submissiveness in the sexual arena.