Developing human-nonhuman chimeras in human stem cell research: ethical issues and boundaries

The transplantation of adult human neural stem cells into prenatal non-humans offers an avenue for studying human neural cell development without direct use of human embryos. However, such experiments raise significant ethical concerns about mixing human and nonhuman materials in ways that could result in the development of human-nonhuman chimeras. This paper examines four arguments against such research, the moral taboo, species integrity, "unnaturalness," and human dignity arguments, and finds the last plausible. It argues that the transfer of human brain or retinal stem cells to nonhuman embryos would not result in the development of human-nonhuman chimeras that denigrate human dignity, provided such stem cells are dissociated. The article provides guidelines that set ethical boundaries for conducting such research that are consonant with the requirements of human dignity.     

The relative effectiveness of various instructional approaches in developing anticipation skill

The relative effectiveness of explicit instruction, guided discovery, and discovery learning techniques in enhancing anticipation skill in young, intermediate-level tennis players was examined. Performance was assessed pre- and postintervention, during acquisition, and under transfer conditions designed to elicit anxiety through the use of laboratory and on-court measures. The 3 intervention groups improved from pre- to posttest compared with a control group (n = 8), highlighting the benefits of perceptual-cognitive training. Participants in the explicit (n = 8) and guided discovery (n = 10) groups improved their performance during acquisition at a faster rate than did the discovery learning (n = 7) group. However, the explicit group showed a significant decrement in performance when tested under anxiety provoking conditions compared with the guided discovery and discovery learning groups. Although training facilitated anticipation skill, irrespective of the type of instruction used in this experiment, guided discovery methods are recommended for expediency in learning and resilience under pressure.     

Prevalence of alcohol use in a rural South African community

Among a community sample of 801 rural South Africans, 22.2% of men and 5.0% of women were classified as high-risk drinkers and 3.3% as with probable alcohol dependence.     

Personality and the predisposition to engage in risky or problem behaviors during adolescence

Longitudinal data from a representative sample of 1,978 Black and White adolescents were used to examine the role of personality in multiple risk or problem behaviors. Results indicate that covariation among diverse behaviors (educational underachievement, delinquent behavior, substance use, sexual behavior) can be adequately modeled by a single higher order factor, and that impulsivity and avoidance coping serve as generalized risk factors for involvement in these behaviors. Whereas none of the personality variables examined explained change in problem behaviors once established, avoidance coping prospectively predicted involvement among a subgroup of adolescents with little or no prior involvement. Results suggest that dysfunctional styles of regulating emotions and emotionally driven behaviors are core features of risky or problem behaviors during adolescence.     

Trunk- and head-centred spatial coordinates do not affect free-viewing perceptual asymmetries

Turning the trunk or head to the left can reduce the severity of leftward neglect. This study sought to determine whether turning the trunk or head to the right would reduce pseudoneglect: A phenomenon where normal participants underestimate the rightward features of a stimulus. Participants made luminance judgements of two mirror-reversed greyscales stimuli. A preference for selecting the stimulus dark on the left was found. The effect of trunk-centred coordinates was examined in Expt. 1 by facing the head toward the display and turning the trunk to the left, right or toward the display. Head-centred coordinates were examined in Expt. 2 by directing the eyes toward the display and then turning the head and trunk. No effect of rotation was observed. It was concluded that the leftward bias for the greyscales task could be based on an object-centred attentional bias or left-to-right eye scanning habits.     

Metaphors and the mental lexicon.

In two experiments we investigate the possibility that lexicalization can account for the distinction between literal and metaphorical language. In both experiments, sentence contexts were presented with the final word missing. When subjects signaled they understood the context, two possible final words were presented and subjects were required to decide which was more appropriate. Semantic decision times over five different types of stimuli investigating literal and metaphorical word usage were consistent with a modified class inclusion model in which both the lexicalized meaning of words and the context in which they are presented make essential contributions to understanding.     

Reducing intergroup bias: elements of intergroup cooperation

The authors examined the potentially separable contributions of 2 elements of intergroup cooperation, interaction and common fate, and the processes through which they can operate. The manipulation of interaction reduced bias in evaluative ratings, which supports the idea that these components are separable, whereas the manipulation of common fate when the groups were interacting was associated with lower bias in nonverbal facial reactions in response to contributions by in-group and out-group members. Whereas interaction activated several processes that can lead to reduced bias, including decategorization, consistent with the common in-group identity model (S. L. Gaertner, J. F. Dovidio, P. A. Anastasio, B. A. Bachman, & M. C. Rust, 1993) as well as M. Hewstone and R. J. Brown's (1986) group differentiation model, the primary set of mediators involved participants' representations of the memberships as 2 subgroups within a superordinate entity.