Standard Experimental Paradigm Research Articles

The design and analysis of cholera vaccine trials: recent lessons from Bangladesh.

The recent spread of cholera to Latin America, together with the persistent burden of this disease in Asia and Africa, have stimulated efforts to evaluate new cholera vaccines in field settings. Although the standard experimental paradigm for vaccine field trials is well established, the success of these trials will also depend on suitable consideration of the epidemiology of cholera and of cholera vaccination in the setting under study. Epidemiological studies done in Bangladesh emphasize the importance of appreciating the poorly predictable, multifocal occurrence of cholera in estimating a probable incidence of cholera for a field trial. They also underscore how the filtering effect of enrolling subjects into a prospective trial can dramatically reduce the available population for study, and can yield a study sample whose expected risk of cholera differs markedly from that for the source population. Finally, the data highlight the subtle effects that the mode of surveillance and the choice of an outcome definition can have upon protective efficacy, and emphasize the need for subgroup analyses that address the distinctive variations in vaccine protection that may occur in subjects differing in age and in ABO blood groups, and in subjects exposed to classical versus El Tor cholera.

Vietnamese Modal Scales of the Dan Tranh

The dan tranh is a Vietnamese 17-string zither tuned to pentatonic modal scales. Each modal scale, or dieu, encompasses a given tuning and a specific sentiment or modal nuance, and ornamentation using pitch bends is an important embellishment. The dan tranh was tuned entirely by ear, and the repetition rate of the lowest-pitched string varied from G₀ to E₃ in data obtained during a 6-month period from a single highly skilled Vietnamese musician. The modal scales lie in two major systems, bac and nam, and the frequency ratios of the tonal materials comprising the scales were measured. Using a standard categorization experimental paradigm, the musician was unable to categorize intervals in the absence of musical context. In a probe-tone rating experiment, the musician was asked to contemplate the sentiment associated with a particular modal scale, and evidence was found that was suggestive of an internalized hierarchy that differed between the two modal scales used as stimuli. Vietnamese modal scales make extensive use of a 166-cent scale step, which corresponds to $\frac{5}{3}$semitones.

Possible influence of strain differences on pregnancy initiation in laboratory rats

Recent research in this laboratory has failed to replicate previous findings that the first ejaculatory series of the male is sufficient to induce a high incidence of pregnancy in female laboratory rats (Rattus norvegicus). The incidence of pregnancy and pseudopregnancy in albino and hooded females were compared in a standard experimental paradigm. Eight percent of Sprague-Dawley albino females exhibited a progestational response, while 45% of the Long-Evans hooded females became progestational. On the basis of these findings, and a lack of previous formal comparison of genetic strains, it is suggested that genetic differences among strains may be at least partially responsible for differences observed in the ability of a single ejaculatory series to impregnate female laboratory rats.

The Computer as Educator: Lessons From Television Research

Research on the educational facets of television has been marred by a number of blunders that stand in danger of being repeated in the new wave of educational research on computers. Despite the clear differences in purpose and scope between television and computers, some useful lessons can be drawn from earlier assumptions about learning from television. In this paper, it is argued that "computer researchers" should do the following: (a) avoid asking whether computers teach better than some putatively comparable medium; (b) utilize holistic as well as standard experimental research paradigms, particularly during the early phases of research; (c) realize that learners bring many assumptions, proclivities, and active learning strategies to any encounter with a new medium or technology; and (d) expect a range of usages and experiences and a variety of outcomes from any encounter between an individual and a computer. It is particularly important to carry out background research during the period before computers became completely pervasive in the educational environment.

Contrast effects in the child’s judgment of lifted weight

In this study on anchor effectiveness, the hypothesis that the locus of inflection points of adaptation level varies with chronological age was tested and confirmed. Altogether 62 Ss, divided into four age groups (4;8-12;11 years) had to judge either a 20- to 180-g weight series or a 200- to 400-g series, with anchor values ranging either from 95 to 1700 g or from 16 to 270 g, according to Helson’s standard experimental paradigm which was slightly modified with regard to children’s testing perceptual response. For children more than 7;0 years old, the anchor-AL trend follows a cubic trend, whereas for younger Ss a monotonic contrast effect trend was obtained. These results are interpreted in terms of cognitive rather than sensory contrast effects in psychophysics.

Children's Use of Context in Judgment of Weight

O'REILLY, EDMOND, and STEGER, JOSEPH A. Children's Use of Context in Judgmentof Weight. CHILD DEVELOPMENT, 1970, 41, 1095-1101. Using the standard psychophysical experimental paradigm employing the anchor as a frame of reference, children ages 5, 6, 7, 9, 11 were required to judge a series of 5 weights. The results show that all subjects over 6 years of age could both order the series (seriate) and shift their judgment of the whole series when presented with an anchor (transitivity). Subjects 5 years could not do either. The results suggest that seriation and the use of a relative frame of reference are cognitively confounded. The age at which these subjects performed these tasks is younger than has been previously noted.