An Active Learning Intervention Based on Evaluating Alternative Hypotheses Increases Scientific Literacy of Controlled Experiments in Introductory Biology

Scientific education provides a set of tools to make sense of a complex world by teasing out complicated cause-and-effect relationships, such as the elimination of effects of confounding factors in controlled experiments. There is evidence that depth of understanding of controlled experiments is lacking among undergraduate science students despite exposure to controlled experiments in courses. To examine the understanding of controlled experiments, we developed a two-tiered assessment that includes closed-ended and open-ended questions, with three types of questions, i.e., (i) a scientific scenario about a flawed drug study, (ii) an everyday-life scenario about flawed thinking regarding product effectiveness, and (iii) a direct question about explaining controlled experiments. Consistent with previous findings, we demonstrated that large percentages of students in introductory biology courses at both a research-intensive institution and a primarily undergraduate, minority-serving institution failed to recognize the need to account for confounds. Based on these findings, we tested the hypothesis that scientific literacy could be improved through a course-based intervention using an active learning framework focused on science as a process of evaluating alternative hypotheses. We found start-to-end-of-semester improvement in students' identification of unaccounted confounds with a scientific scenario in an intervention course but not in the control course. Interestingly, students in both the control and intervention courses showed improvement when tested with a scenario based on everyday life. The study findings suggest that a concerning number of college students may not account sufficiently for uncontrolled variables in real-life situations, and we present a widely applicable instructional strategy that improves on this broadly relevant scientific reasoning skill.

Two-tailed significance tests for 2 × 2 contingency tables: What is the alternative?

Two-tailed significance testing for 2 × 2 contingency tables has remained controversial. Within the medical literature, different tests are used in different papers and that choice may decide whether findings are adjudged to be significant or nonsignificant; a state of affairs that is clearly undesirable. In this paper, it is argued that a part of the controversy is due to a failure to recognise that there are two possible alternative hypotheses to the Null. It is further argued that, while one alternative hypothesis can lead to tests with greater power, the other choice is more applicable in medical research. That leads to the recommendation that, within medical research, 2 × 2 tables should be tested using double the one-tailed exact probability from Fisher's exact test or, as an approximation, the chi-squared test with Yates' correction for continuity.

How scientists perceive the evolutionary origin of human traits: Results of a survey study

Various hypotheses have been proposed for why the traits distinguishing humans from other primates originally evolved, and any given trait may have been explained both as an adaptation to different environments and as a result of demands from social organization or sexual selection. To find out how popular the different explanations are among scientists, we carried out an online survey among authors of recent scientific papers in journals covering relevant fields of science (paleoanthropology, paleontology, ecology, evolution, human biology). Some of the hypotheses were clearly more popular among the 1,266 respondents than others, but none was universally accepted or rejected. Even the most popular of the hypotheses were assessed "very likely" by <50% of the respondents, but many traits had 1-3 hypotheses that were found at least moderately likely by >70% of the respondents. An ordination of the hypotheses identified two strong gradients. Along one gradient, the hypotheses were sorted by their popularity, measured by the average credibility score given by the respondents. The second gradient separated all hypotheses postulating adaptation to swimming or diving into their own group. The average credibility scores given for different subgroups of the hypotheses were not related to respondent's age or number of publications authored. However, (paleo)anthropologists were more critical of all hypotheses, and much more critical of the water-related ones, than were respondents representing other fields of expertise. Although most respondents did not find the water-related hypotheses likely, only a small minority found them unscientific. The most popular hypotheses were based on inherent drivers; that is, they assumed the evolution of a trait to have been triggered by the prior emergence of another human-specific behavioral or morphological trait, but opinions differed as to which of the traits came first.

Cognitive processes underlying human mate choice: The relationship between self-perception and mate preference in Western society

This study tested two hypotheses concerning the cognitive processes underlying human mate choice in Western society: (i) mate preference is conditional in that the selectivity of individuals' mate preference is based on their perception of themselves as long-term partners, and (ii) the decision rule governing such conditional mate preference is based on translating perception of oneself on a given attribute into a comparable selectivity of preference for the same attribute in a mate. Both hypotheses were supported. A two-part questionnaire was completed by 978 heterosexual residents of Ithaca, New York, aged 18-24; they first rated the importance they placed on 10 attributes in a long-term partner and then rated their perception of themselves on those same attributes. Both women and men who rated themselves highly were significantly more selective in their mate preference. When the 10 attributes were grouped into four evolutionarily relevant categories (indicative of wealth and status, family commitment, physical appearance, and sexual fidelity), the greatest amount of variation in the selectivity of mate preference in each category was explained by self-perception in the same category of attributes. We conclude that, in Western society, humans use neither an "opposites-attract" nor a "reproductive-potentials-attract" decision rule in their choice of long-term partners but rather a "likes-attract" rule based on a preference for partners who are similar to themselves across a number of characteristics.