Chronic stress impairs recall of extinction of conditioned fear

Chronic restraint stress produces retraction of apical dendrites of pyramidal neurons in medial prefrontal cortex. To begin to examine the functional significance of this dendritic reorganization, we assessed the effects of chronic restraint stress on a prefrontally mediated behavior, extinction of conditioned fear. After bar press training to obtain a baseline of activity against which to measure freezing, rats were either unstressed or stressed via placement in a plastic restrainer (3 h/day for 1 week). After an additional day of bar press training, rats underwent fear conditioning and extinction. Rats received five habituation trials to a 30-s tone (4.5 kHz, 80 db) followed by seven pairings of tone and footshock (500 ms, 0.5 mA). One hour later, rats received tone-alone extinction trials to criterion. The next day, rats received 15 additional extinction trials. Percent freezing was assessed during all phases of training. Stress did not significantly affect unconditioned responding to tone, acquisition of conditioned fear, or initial extinction, but significantly increased freezing on extinction day 2. Thus, consistent with the regressive dendritic changes seen in medial prefrontal cortex, one week of restraint stress specifically impaired recall of extinction, a pattern of deficits typical of animals with impaired medial prefrontal function.     

The emergence of children's causal explanations and theories: evidence from everyday conversation

This research examines the content of explanations that 4 English-speaking children gave or asked for in everyday conversations recorded from 2 1/2 to 5 years of age. Analyses of nearly 5,000 codable explanations (identified by markers like why or because) focused on the entity targeted for explanation (e.g., person, animal, object), the explanatory mode of causal reasoning (e.g., psychological, physical), and interrelations between these elements. Children's explanations focused on varied entities (animals, objects, and persons) and incorporated diverse modes (psychological, physical, social-conventional, and even biological reasoning). Children's pairings of entities with explanatory modes suggest appropriately constrained yet flexible causal reasoning. These data are consistent with the hypothesis that young children draw on several complementary causal-explanatory theories to make sense of real-life events.     

Variations in hand position, cerebral lateralization, and reading ability among right-handed children

A group of 121 right-handed children between the ages of 7 and 9 with a range of hand positions between normal and inverted were assessed for verbal and visuospatial lateralization and reading comprehension. Results indicate that (a) children with a normal hand position tended to be more verbally lateralized than children with nonnormal positions, although the effect was not strong or always consistent, (b) the closer the child was to the normal position, the higher the child's reading scores, and (c) poor readers were as lateralized for verbal and visuospatial functions as were good readers. Coupled with the results of previous research, these findings suggest that hand position indexes both maturation and lateralization, and that the relationship between hand position and reading is primarily mediated by the former.     

Infants' use of social partnerships to predict behavior

The experiences of social partners are important motivators of social action. Can infants use such experiences to make predictions about how social agents will behave? Sixteen‐month‐old infants were introduced to two social pairs. Initial events established within‐pair cooperation as well as between‐pair conflict involving an individual from each pair. Following these events, infants looked longer when between‐pair members who had never previously interacted now cooperated – instead of conflicted – with each other. Thus, infants tracked the third‐person allegiances and inferred that the conflict would generalize across social partnerships. These findings demonstrate a critical feature of early social cognition and promote needed, further research on the role of social allegiances in social cognition across development.     

Status legitimizing beliefs predict positivity toward Whites who claim anti-White bias

Although Whites are increasingly likely to perceive themselves as victims of racial bias, research provides little insight into how anti-White bias claimants are perceived. Two studies examined whether Whites' endorsement of status legitimizing beliefs (SLBs) moderates their reactions toward White discrimination claimants. In Study 1, Whites who rejected SLBs reacted less favorably to an anti-White bias claimant relative to one who made a nondiscriminatory external claim, whereas Whites who endorsed SLBs expressed equally positive attitudes toward an anti-White bias claimant and a non-claimant. In Study 2, Whites who were not primed with status legitimizing beliefs displayed negative reactions toward an anti-White bias claimant compared to a non-claimant, whereas those primed with SLBs expressed more positive attitudes and a desire to help the anti-White bias claimant. Implications for affirmative action litigation are discussed.     

Preventing Contagion With Avian Influenza: Disease Salience,Attitudes Toward Foreigners,and Avoidance Beliefs1

Building on an evolutionary approach to out‐group avoidance, this study showed relations between perceived disease salience and beliefs in the efficacy of avoiding foreigners as protective measures in the context of a real‐life pandemic risk; i.e., avian influenza. People for whom avian influenza was salient and who held unfavorable attitudes toward foreigners were more likely to believe that avoiding contact with foreigners protects against infection. This finding suggests that individual differences in social attitudes moderate evolved mechanisms relating threat of disease to out‐group avoidance.     

Neural correlates of belief- and desire-reasoning in 7- and 8-year-old children: an event-related potential study

Theory of mind requires belief‐ and desire‐understanding. Event‐related brain potential (ERP) research on belief‐ and desire‐reasoning in adults found mid‐frontal activations for both desires and beliefs, and selective right‐posterior activations only for beliefs. Developmentally, children understand desires before beliefs; thus, a critical question concerns whether neural specialization for belief‐reasoning exists in childhood or develops later. Neural activity was recorded as 7‐ and 8‐year‐olds (N = 18) performed the same diverse‐desires, diverse‐beliefs, and physical control tasks used in a previous adult ERP study. Like adults, mid‐frontal scalp activations were found for belief‐ and desire‐reasoning. Moreover, analyses using correct trials alone yielded selective right‐posterior activations for belief‐reasoning. Results suggest developmental links between increasingly accurate understanding of complex mental states and neural specialization supporting this understanding.     

Children's understanding of food and its functions: A preliminary study of the development of concepts of nutrition

Children's developing conceptions of how the body functions nutritionally were examined. Two different tasks provided converging findings. One task asked children to judge the causes of certain end states (e.g., why X is fat). The second task asked children to judge the result of certain contrasting diets (e.g., twin-1 eats twice as much candy as twin-2). The results evidenced; (a) systematic misconceptions on the part of kindergarteners that were overcome by sixth grade; and (b) other fairly sophisticated conceptions present even at the youngest ages tested. The research provides a needed first step toward describing the naive theories of nutrition possessed by children at different ages. Knowledge of childrens' theories of nutrition are essential for optimal planning of curricula and methods in nutrition education.