Guided group discussion and attitude change: The roles of normative and informational influence

Kurt Lewin and others have showed that group discussion effectively changed attitudes and behaviors compared to individually targeted messages. This study examines the roles of normative and informational social influence in this effect. High school students heard a message about replacing toxic products with nontoxic alternatives; classes were randomly assigned to hear the message delivered as a lecture or via guided group discussion. For female students (N=250 in 26 classes), HLM mediation analyses suggested normative influence predominated: Discussion was more effective than lecture and this effect was fully mediated by students’ perceptions that other students endorsed nontoxics. Content analyses of students’ comments indicated that three kinds of remarks led female students to this perception: (1) sharing knowledge about nontoxics; (2) asking questions about nontoxics; and (3) little praise for toxic products. For male students in separate HLM analyses (N=107 in 19 of the same classes), informational influence was most apparent: Postmeeting attitudes were higher after discussion than lecture, and this effect was partially mediated by cognitive elaboration about the message (but not perceptions others endorsed the message). In addition, males’ quiz grades were higher after discussion, and students’ comments fully mediated the discussion to quiz grades relationship. Results support the importance of hearing others’ promessage comments for changing socially motivated behaviors, although the routes of influence appear to differ for these samples of male and female students.     

Statistical Issues for Monitoring Ecological and Natural Resources in the United States

The United States funds a number of national monitoring programs to measure the status and trends of ecological and natural resources. Each of these programs has a unique focus; the scientific objectives are different as are the sample designs. However, individuals and committees, all well aware of the cost of ecological monitoring, have called for more effective monitoring programs. The objective of this paper is to summarize existing programs' statistical designs and discuss potential alternatives for improvement in national monitoring. Can we improve the current situation by providing an overall framework for the design or analysis of data from these disparate surveys? First, the paper summarizes the objectives of these surveys, compares and contrasts their survey designs as currently implemented, and determines what variables they collect. Through this process we identify commonalities and issues that impact our ability to combine information across one or more of the surveys. Three potential alternatives are presented, leading to comprehensive monitoring in the United States.     

Phenotypic Alterations, Evolutionarily Significant Structures, and Rhino Conservation

To slow the impending loss of wild black ( Diceros bicornis ) and white ( Ceratotherium simum ) rhinos, three African countries have resorted to dehorning, a practice designed to remove the incentive for poachers to kill the hornless animals. The efficacy of this controversial conservation action remains unknown, in part because much uncertainty exists about the functional significance of rhino horns. We assessed the current utility of horns in Namibian black rhinos from phenotypically altered and intact populations in the Namib Desert, and we collated data on mortal fighting among horned females living in Etosha National Park. Infant mortality was 100% when dehorned mothers were sympatric with spotted hyenas ( Crocuta crocuta ). In contrast, infant survival was 100% for both horned mothers living with hyenas and occasional lions ( Panthera leo ) and 100% for dehorned mothers in the absence of dangerous carnivores. These data suggest that female horns can have direct fitness benefits in terms of calf survival. However, because lethal wounding due to fighting may account for up to 33% of the mortality of horned females, dehorning may improve adult survivorship. Our results (1) suggest that, where the aim of conservation programs is to improve population viability through juvenile recruitment, dehorning is unlikely to be a prudent strategy if practiced in areas with dangerous predators, and (2) illustrate the value of experimental approaches to onerous problems in conservation.     

Nest association in fishes: evidence for mutualism

Nest association, or the habit of spawning in the nest of another species, is a widespread reproductive strategy among North American fishes, especially minnows. The hosts of nest associates include sunfishes and nest-building minnows. Previous experiments demonstrated that nest associates benefited from the parental care of hosts. The purpose of this study was to determine the effect of nest associates on hosts, and thereby characterize the relationship as parasitic, mutualistic or commensal. Since hosts with associates had higher reproductive success than those without associates in this experiment, I characterize nest association as a mutualistic relationship, at least in some systems. The dilution effect is the proposed mechanism responsible for the higher reproductive success of hosts with associates.     

Particulate organic matter in the sea: the composition conundrum

As organic matter produced in the euphotic zone of the ocean sinks through the mesopelagic zone, its composition changes from one that is easily characterized by standard chromatographic techniques to one that is not. The material not identified at the molecular level is called "uncharacterized". Several processes account for this transformation of organic matter: aggregation/disaggregation of particles resulting in incorporation of older and more degraded material; recombination of organic compounds into geomacromolecules; and selective preservation of specific biomacromolecules. Furthermore, microbial activities may introduce new cell wall or other biomass material that is not easily characterized, or they may produce such material as a metabolic product. In addition, black carbon produced by combustion processes may compose a fraction of the uncharacterized organic matter, as it is not analyzed in standard biochemical techniques. Despite these poorly-defined compositional changes that hinder chemical identification, the vast majority of organic matter in sinking particles remains accessible to and is ultimately remineralized by marine microbes.     

Forecasting the Effects of Land-Use Change on Forest Rodents in Indiana

Forest cover in the upper Wabash River basin in Indiana was fragmented due to agricultural conversion beginning more than 175 years ago. Currently, urban expansion is an important driver of land-use change in the basin. A land transformation model was applied to the basin to forecast land use from 2000 to 2020. We assessed the effect of this projected land-use change scenario on five forest rodent species at three scales: using occupancy models at the patch level, proportional occupancy models at the landscape level, and ecologically scaled landscape indices to assess the change in connectivity at the watershed level. At the patch and landscape scales, occupancy models had low predictability but suggest that gray squirrels are most susceptible to land-use change. At the watershed scale, declines in connectivity did not correspond with the decline of forest. This study highlights the importance of map resolution and consideration of matrix elements in constructing forecast models. Unforeseen drivers of land use, such as changing economic incentives, may also have important ramifications.