The influence of the order and congruency of correct and erroneous worked examples on learning and (meta-)cognitive load.

Several studies highlight the importance of the order of different instructional methods when designing learning environments. Correct but also erroneous worked examples are frequently used methods to foster students' learning performance, especially in problem-solving. However, so far no study examined how the order of these example types affects learning. While the expertise reversal effect would suggest presenting correct examples first, the productive failure approach hypothesizes the reversed order to be learning-facilitating. In addition, congruency of subsequent exemplified problems was tested as a moderator of the effect of order on learning. For example, with arithmetic tasks, congruent problems target exactly the same calculation while incongruent problems refer to different calculations. Following cascade theory, a model of cognitive skill acquisition, presenting correct examples first should be more effective when the subsequent exemplified problems are different. To test the (conflicting) hypotheses, 83 university students were assigned to one of the four conditions in a 2 (correct vs. erroneous example first) × 2 (same vs. different exemplified problems) between-subject design. Learners navigated through a slideshow on the topic of Vedic mathematics consisting of explicit instruction, worked examples differing in terms of the experimental condition, and transfer problems. Although no main or interaction effects were found regarding students' learning performance, mediational analysis offered support for the expertise reversal effect, as it indicated that there is a significant indirect effect of order via mental load on learning. Presenting correct examples first and erroneous examples second resulted in a lower mental load, which in turn was associated with better learning performance. In contrast, presenting erroneous examples first and correct examples second resulted in a more accurate self-assessment of learning performance. These findings offer first insights into the question of how the presentation order of different example types impacts learning and provide practical recommendations for the design of educational media. Results are discussed in light of the ongoing debate regarding the question if less guided instructional methods should precede or succeed more guided methods.

HIV prevention cascade theory and its relation to social dimensions of health: a case for Nigeria.

BACKGROUND: Nigeria has the second largest HIV epidemic in the world and one of the highest rates of new infection in sub-Saharan Africa. Within the last three decades, majority of HIV programs in Nigeria were treatment strategies with few prevention approaches. The persistence of HIV prevalence despite the treatment blueprint has led to a concerted call to HIV Prevention Cascade (HPC) theory which ensures continuous sophisticated interrelationship that stretches beyond the biomedical interventions of treatment. To our knowledge, there is no previous review on HPC theory in Nigerian context. OBJECTIVES: The aim of this review was to explore and outline the HIV/AIDS prevention cascade theory in relation to the achievement of the global 90-90-90 target set by the United Nations Programme on HIV and AIDS and suggest possible avenues to maximize on strengths and weaknesses of HPC in Nigeria. METHODS: In this mini-review, the authors utilized standardized search measures in the review of published articles in credible domains across the HPC in PubMed, Research gate, Google Scholar, Mendeley Reference Manager and Cochrane Library from January 1980 to December 2018. Referenced sections of the articles identified were used to hand-search additional references not retrieved by the initial search engines. The authors performed an evaluation of selected studies on three cascade theories: epidemiological, behavioral and social science with an integration of the supply, demand and adherence sides. RESULTS: We included nine review articles reporting three different cascade theories. Only one included study applied the cascade theories exclusively in Nigerian context. We could only conduct narrative synthesis. CONCLUSION: There is scarceness of currently published evidence on HPC in Nigerian context. HPC allows for a paradigm shift and sequential process of events to eliminate the epidemic of HIV using HIV prevention perspectives in Nigerian settings. Since data are sparse, more research is needed on HPC theory.

Alzheimer's disease and immunotherapy: what is wrong with clinical trials?

Alzheimer's disease (AD) is characterized by progressive neurodegeneration and is the most common cause of dementia. Immunotherapy has recently been regarded as a potential treatment for AD. This stems from the fact that the clinical and pathological findings from the active AD vaccine trial suggests that such vaccine therapy may be effective for AD. However, this trial was halted because of the occurrence of meningoencephalitis in some patients. Avoiding excessive immune reaction is necessary for the success of vaccine therapy. For this purpose, adjuvant-free vaccine therapies (eg, passive immunization or DNA vaccines) are currently under investigation. However, the results of clinical trials employing both active and passive anti-amyloid-beta immunotherapy have been unsatisfactory. In this article, we will analyze the reasons for the limited efficacy of currently available immunotherapies and discuss the effectiveness of new vaccine therapies. Finally, we will speculate on the possibility of its clinical application.