Multiple cue use and integration in pigeons (<Emphasis Type="Italic">Columba livia</Emphasis>)

Encoding multiple cues can improve the accuracy and reliability of navigation and goal localization. Problems may arise, however, if one cue is displaced and provides information which conflicts with other cues. Here we investigated how pigeons cope with cue conflict by training them to locate a goal relative to two landmarks and then varying the amount of conflict between the landmarks. When the amount of conflict was small, pigeons tended to integrate both cues in their search patterns. When the amount of conflict was large, however, pigeons used information from both cues independently. This context-dependent strategy for resolving spatial cue conflict agrees with Bayes optimal calculations for using information from multiple sources.     

Ethnicity-Related Sources of Stress and Their Effects on Well-Being

Early research on ethnicity focused on the stereotyped thinking, prejudiced attitudes, and discriminatory actions of Euro-Americans. Minority-group members were viewed largely as passive targets of these negative reactions, with low self-esteem studied as the main psychological outcome. By contrast, recent research has increasingly made explicit use of stress theory in emphasizing the perspectives and experiences of minority-group members. Several ethnicity-related stressors have been identified, and it has been found that individuals cope with these threats in an active, purposeful manner. In this article, we focus on ethnicity-related stress stemming from discrimination, from stereotypes, and from conformity pressure arising from one's own ethnic group. We discuss theory and review research in which examination of ethnicity-related outcomes has extended beyond self-esteem to include psychological and physical well-being.     

The Effect of External and Internal Focus of Attention on Gait Variability in Older Adults

Internal focus of attention on a movement or focusing on an external target are both strategies that can affect motor performance. The authors explored whether manipulating subjects' focus of attention while walking would alter gait variability, a measure reflecting consistency of gait and associated with the risk of falling in older adults. Twenty community-living older adults participated in the study and were tested while focusing their attention on (a) gait consistency (internal focus) or (b) metronome beats (external focus). In both conditions gait variability increased (i.e., worsened p < .05) or did not change. No benefit was found in instructing subjects to focus on gait consistency or metronome beats. Such instructions may actually have distracted and interfered with the execution of gait.     

The effect of arm crossing on persistence and performance

Two experiments investigated the hypothesis that arm crossing serves as a proprioceptive cue for perseverance within achievement settings. Experiment 1 found that inducing participants to cross their arms led to greater persistence on an unsolvable anagram. Experiment 2 revealed that arm crossing led to better performance on solvable anagrams, and that this effect was mediated by greater persistence. No differences in comfort, instruction adherence, or mood were observed between the arms crossed and control conditions, and participants appeared to be unaware of the effect of arm crossing on their behavior. Implications of the findings are discussed in terms of the interplay between proprioceptive cues and contextual meaning. Copyright © 2007 John Wiley & Sons, Ltd.     

STEREOTYPE THREAT AND THE GENDER GAP IN POLITICAL KNOWLEDGE

Men tend to achieve higher response accuracy than women on surveys of political knowledge. We investigated the possibility that this performance gap is moderated by factors that render the communicative context of a survey intellectually threatening to women and thereby induce stereotype threat. In a telephone survey of college students' political knowledge, we manipulated two factors of the survey context: the alleged diagnosticity of the question set (i.e., whether it was portrayed as being sensitive to potential gender differences) and the gender of the interviewer. Consistent with previous studies of political knowledge, men scored higher than women overall. However, as predicted, this difference was reliably moderated by the manipulated factors. Women's scores were not reliably different from men's when the survey was portrayed as nondiagnostic and when women were interviewed by female interviewers. Diagnosticity and interviewer gender had no effects on men's scores. Consistent with previous research on stereotype threat, these results suggest that explicit and implicit cues reminding women of the possibility that they might confirm a negative gender stereotype can impair their retrieval of political knowledge.     

When stereotypes disadvantage boys: Strength of stereotypes in mathematics and language arts and their relations with grades

There is growing concern about boys' lagging performance in school, not only in language arts, where the gap is particularly pronounced, but also in mathematics. Stereotypes associating one gender with language arts or with mathematics are likely to contribute to these gaps. Such stereotypes can translate into explicit beliefs such as the extent to which students are aware of societal stereotypes or the extent to which they personally believe stereotypes to be true, but also indirectly into performance following a stereotype threat manipulation. However, few studies have considered these multiple stereotype expressions in both mathematics and language arts to examine their importance in predicting boys' and girls' actual grades in school. To fill this gap, two complementary studies examined high school boys' and girls' awareness and endorsement of stereotypes about both language arts (n = 299) and mathematics (n = 243), as well as whether stereotype threat impaired boys' performance on a spelling test. Although the effect of stereotype threat was not significant overall, our results showed that students were aware of and endorsed strong stereotypes advantaging girls in language arts. In mathematics, students endorsed counter-traditional stereotypes slightly advantaging girls. Our results also showed that these multiple expressions of stereotypes related to students' grades. In doing so, our work provides insights regarding possible targets for interventions to reduce gender gaps disadvantaging boys in school.     

Dynamic action units slip in speech production errors

In the past, the nature of the compositional units proposed for spoken language has largely diverged from the types of control units pursued in the domains of other skilled motor tasks. A classic source of evidence as to the units structuring speech has been patterns observed in speech errors--"slips of the tongue". The present study reports, for the first time, on kinematic data from tongue and lip movements during speech errors elicited in the laboratory using a repetition task. Our data are consistent with the hypothesis that speech production results from the assembly of dynamically defined action units--gestures--in a linguistically structured environment. The experimental results support both the presence of gestural units and the dynamical properties of these units and their coordination. This study of speech articulation shows that it is possible to develop a principled account of spoken language within a more general theory of action.     

The effects of reinforcer magnitude on timing in rats

The relation between reinforcer magnitude and timing behavior was studied using a peak procedure. Four rats received multiple consecutive sessions with both low and high levels of brain stimulation reward (BSR). Rats paused longer and had later start times during sessions when their responses were reinforced with low-magnitude BSR. When estimated by a symmetric Gaussian function, peak times also were earlier; when estimated by a better-fitting asymmetric Gaussian function or by analyzing individual trials, however, these peak-time changes were determined to reflect a mixture of large effects of BSR on start times and no effect on stop times. These results pose a significant dilemma for three major theories of timing (SET, MTS, and BeT), which all predict no effects for chronic manipulations of reinforcer magnitude. We conclude that increased reinforcer magnitude influences timing in two ways: through larger immediate after-effects that delay responding and through anticipatory effects that elicit earlier responding.