Showing papers by "David W. Johnson published in 1985"
TL;DR: In this paper, the impact of computer-assisted cooperative, competitive, and individualistic instruction on student achievement and attitudes was compared on SAT test items, and it was found that computer assisted cooperative instruction promotes greater quantity and quality of daily achievement, more successful problem solving, and higher performance on factual recognition, application, and problem-solving test items than do computer assisted competitive learning.
Abstract: : The impact of computer-assisted cooperative, competitive, and individualistic instruction was compared on student achievement and attitudes. Seventy-three eighth-grade students were randomly assigned to conditions stratifying for sex and ability. In all conditions students completed the same computer-assisted instructional unit. Results indicate that computer-assisted cooperative instruction promotes greater quantity and quality of daily achievement, more successful problem solving, and higher performance on factual recognition, application, and problem-solving test items than do computer-assisted competitive or individualistic learning. The attitudes of females, compared with males, were adversely affected within the competitive condition.
236 citations
TL;DR: In this paper, the effects of cooperative learning in which oral discussion was structured (to ensure oral summarization and the monitoring of others' summaries) and individualistic learning were compared on daily achievement, post-instructional achievement, and retention.
Abstract: : The effects of cooperative learning in which oral discussion was structured (to ensure oral summarization and the monitoring of others' summaries), cooperative learning in which oral discussion was unstructured, and individualistic learning were compared on daily achievement, post-instructional achievement, and retention. Seventy-five second grade students were randomly assigned to the three conditions stratifying for sex and ability level. The results indicate that students in cooperative groups performed significantly higher on the accuracy of daily work than do students working individualistically. In addition, the high-, medium-, and low-ability students in the structured oral discussion cooperative condition scored higher on the post-instructional and retention tests (which were taken individually) than did the students in the other two conditions, and the students in the unstructured oral discussion cooperative condition scored higher on these tests did the students who had learned individualistically. These results indicate that group-to-individual transfer does take place within cooperative learning groups and that orally summarizing the material being learned and the monitoring of others' summaries contributes to the efficacy of cooperative learning. Keywords: Cooperation; Achievement; Oral Discussion.
211 citations
01 Jan 1985
TL;DR: For the past 10 years, the authors have been conducting a systematic program of research on the relative impact of cooperative, competitive, and individualistic learning experiences on such variables as achievement and relationships among students.
Abstract: For the past 10 years, we have been conducting a systematic program of research on the relative impact of cooperative, competitive, and individualistic learning experiences on such variables as achievement and relationships among students. One major focus of our research program has been to illuminate the internal processes within cooperative learning groups that mediate or moderate the relationship between cooperation and (1) productivity and (2) interpersonal attraction among students.
169 citations
TL;DR: In this paper, the effects of two types of structured academic conflict, controversy and debate, were compared with individual study on a number of dependent variables, and the results indicated that controversy promotes the most verbal rehearsal and exchange of the assigned material, the most concern that all students master the assig...
Abstract: The effects of two types of structured academic conflict, controversy and debate, were compared with individual study on a number of dependent variables. Seventy-two sixth grade students were assigned to conditions on a stratified random basis controlling for sex, reading ability, and handicapping conditions. In all three conditions students studied a controversial issue with materials representing both pro and con views. In the controversy condition each learning group was divided into two pairs representing the pro and con sides. In the debate condition each member of a learning group was assigned a pro or con position to represent in a debate with the other three members. In the individualistic condition subjects were told to learn the material without interacting with other students, and each student was given all the pro and con materials. The results indicate that controversy promotes the most verbal rehearsal and exchange of the assigned material, the most concern that all students master the assig...
156 citations
TL;DR: This paper found that cooperative learning was highly related to social support within the classroom and that the longer and more frequently students engaged in cooperative learning, the greater the social support in the classroom.
Abstract: This study was conducted to determine whether cooperative learning experiences are related to social support in the classroom. The relationship between cooperative learning and social support, the impact of prolonged implementation of cooperative learning on social support, and the effect of different frequency of cooperative learning experiences on social support in the classroom were investigated. An instrument measuring social support was administered in November and in January to 91 eighth-grade students from a suburban school district in the Midwest. The results indicate that cooperative learning was highly related to social support within the classroom and that the longer and more frequently students engaged in cooperative learning, the greater the social support within the classroom.
150 citations
113 citations
TL;DR: Vocalizing was found to be more strongly related to achievement than was listening to other group members vocalize, and medium and low achievers especially benefited from cooperative learning experiences.
Abstract: Oral interaction within cooperative learning groups was observed for high-, medium-, and low-achieving students. Initially, cooperative and individualistic learning situations were compared on achievement and attitudes. Forty-eight 4th- grade American students were assigned to learning situations on a stratified random basis controlling for ability and sex. They participated in the study for 55 min a day for 15 instructional days. Two observation schemes were used. The results for the cooperative situation were factor analyzed to determine the basic dimensions of oral interaction within cooperative learning groups. Five orthogonal factors were identified: Exchanging Task-Related Information, Elaborating on the Information, Encouraging Each Other to Learn, Disagreeing With Each Other's Conclusions, and Making Nontask Comments and Sharing Personal Feelings. The oral participation of students from different achievement levels was differentially related to achievement. Vocalizing was found to be more...
82 citations
TL;DR: The results indicated that cooperative learning situations, compared with individualistic ones, promoted more positive cross-sex and cross-handicap relationships as mentioned in this paper, indicating that males achieved higher and had more positive attitudes toward science than did females.
Abstract: Single-sex cooperative, mixed-sex cooperative, and individualistic learning situations were compared to determine if they promoted systematic differences in relationships between male and female students and handicapped and nonhandicapped students. One-hundred-fifty-four 5th-and 6th-grade students were assigned to conditions on a stratified random basis controlling for ability, sex, grade level, homerooms, and handicap. They participated in a study for 45 minutes a day for 21 days in science class. The results indicate that cooperative learning situations, compared with individualistic ones, promoted more positive cross-sex and cross-handicap relationships. Males achieved higher and had more positive attitudes toward science than did females.
64 citations
61 citations
TL;DR: In this paper, the effects of cooperative and individualistic learning contingencies on interpersonal attraction, social acceptability, and self-esteem between handicapped and non-handicapped fourth-grade students were tracked and compared.
52 citations
TL;DR: In this paper, the magnetic susceptibilities of a series of cluster carbonyl compounds of osmium have been measured by a high-sensitivity Faraday method and the evolution of certain aspects of "metallic" behaviour in the high-nuclearity clusters is revealed by a steady increase in the excess molecular susceptibility as the cluster size increases.
Abstract: The magnetic susceptibilities of a series of cluster carbonyl compounds of osmium have been measured by a high-sensitivity Faraday method and the evolution of certain aspects of ‘metallic’ behaviour in the high-nuclearity clusters is revealed by a steady increase in the excess molecular susceptibility as the cluster size increases. We also consider here ‘metallic’ status in the cluster compounds of other transition elements.
TL;DR: The effects of cooperative-controversy, cooperative-concurrence seeking, and individualistic learning were compared on motivation, achievement, and attitudes toward the science subject being studied.
Abstract: The effects of cooperative-controversy, cooperative-concurrence seeking, and individualistic learning were compared on motivation, achievement, and attitudes toward the science subject being studied. Eighty-four fifth-grade students were assigned to conditions on a stratified random basis controlling for sex and reading ability. In all three conditions students studied whether wolves should or should not be a protected species. The results indicate that cooperative-controversy resulted in the highest achievement, greatest motivation to learn more about wolves, more positive attitudes toward the wolf, and more positive attitudes toward controversy.
TL;DR: The results suggest that changes in the T8 population from the blood of patients with MS involve cytotoxic as well as suppressor cells.
Abstract: A single-cell cloning technique was used to analyze both phenotype and function of individual T cells in patients with multiple sclerosis (MS). Blood and cerebrospinal fluid (CSF) lymphocytes were plated at 1 cell per well, stimulated with phytohemagglutinin followed by interleukin 2, and expanded to 3 X 10(6) cells per "clone." More than 90% of the T8 clones generated from patients with MS and controls in both blood and CSF were cytotoxic precursors. There was also a slight decrease in cytotoxic T4 clones in the blood of patients with MS. The cytotoxic precursor frequencies of T cells in the CSF generally reflected those in the blood. In separate experiments, antigen reactivity was examined in lines established from blood or CSF. No reactivity to myelin basic protein or white matter was found in patients with MS or controls. Myelin basic protein-reactive clones could, however, be generated after first stimulating lymphocytes with antigen before cloning. These results suggest that changes in the T8 population from the blood of patients with MS involve cytotoxic as well as suppressor cells. Sequestration of myelin basic protein- or white matter-reactive T cells was not seen in the CSF of patients with MS, unlike reports of viral meningoencephalitis, in which large numbers of antigen-specific cells were found in the CSF. Direct single-cell clonal analysis of the CSF should provide a more sophisticated approach to the study of T cell abnormalities in patients with MS.
TL;DR: In this article, the 2.5 MeV neutron emission from the beam-target d(d, n)3He fusion reaction has been examined for all PDX deuterium plasmas which were heated by neutral beams and the time evolution of the neutron emission through fishbone events was measured and used to determine the confinement properties of the energetic beam ions.
Abstract: The 2.5 MeV neutron emission from the beam-target d(d, n)3He fusion reaction has been examined for all PDX deuterium plasmas which were heated by deuterium neutral beams. The magnitude of the emission was found to scale classically and to increase with as expected when electron drag is the primary energy degradation mechanism. The time evolution of the neutron emission through fishbone events was measured and used to determine the confinement properties of the energetic beam ions. Many of the experimental results are predicted by the Mode Particle Pumping Theory.
TL;DR: The TFTR Thomson scattering system has been operational since January 1984 as discussed by the authors and uses two ruby lasers and two spectrometer-detector systems to provide profiles at two times in a discharge.
Abstract: The TFTR Thomson scattering system has been operational since January 1984. The diagnostic uses two ruby lasers and two spectrometer‐detector systems to provide profiles at two times in a discharge. The two scattering lines consist of 76 spatial channels which span the 200‐cm vacuum vessel along a major radius. The detectors are gated, intensified CCD arrays with single photoelectron sensitivity. Te(R) and Ne(R) profiles are presented.
TL;DR: The effects of controversy and concurrence seeking and participation is age-homogeneous and age-heterogeneous cooperative learning groups were compared on achievement, achievement motivation, perspective-taking accuracy, and interpersonal attraction as discussed by the authors.
Abstract: The effects of controversy and concurrence seeking and participation is age-homogeneous and age-heterogeneous cooperative learning groups were compared on achievement, achievement motivation, perspective-taking accuracy, and interpersonal attraction. In addition, the interaction among students within the cooperative learning groups was observed. One-hundred-twelve 4th-, 5th-, and 6th-grade students were assigned to conditions on a stratified random basis controlling for age, sex, reading ability, and homerooms. In all conditions, students studied two controversial issues with materials representing both pro and con views. In the controversy condition each small group was divided into two halves representing the pro and con sides. In the concurrence-seeking condition each small group studied pro and con materials on alternating days and were told to learn the material without arguing or disagreeing with one another. In the multi-age conditions 4th-, 5th, and 6th-graders were placed in the same learning groups, while in the single-age conditions students were placed in small groups with peers of the same age. The results indicate that controversy promoted higher achievement, greater achievement motivation, and more accurate perspective taking than did concurrence seeking. Multi-age learning groups had greater achievement motivation than did the single-age groups.
TL;DR: In this article, the authors compared intergroup cooperation and competition to determine their impact on cross-ethnic relationships and found that more positive crossethnic relationships were promoted by inter-group cooperation than by intergroup competition.
Abstract: Intergroup cooperation and competition were compared to determine their impact on cross-ethnic relationships. We assigned 48 sixth-grade students to conditions stratifying for minority status, ability, and sex. They participated in a study for 55 min a day for 10 instructional days. The results indicated that more positive cross-ethnic relationships were promoted by intergroup cooperation than by intergroup competition.
TL;DR: Minnesota Orchestra members evaluated with a hearing history questionnaire, otolaryngologic examination, and pure tone audiometry for the conventional and extended high frequency ranges had no significant correlation with hearing loss.
Abstract: Minnesota Orchestra members (42 males, 18 females) aged 24 to 64 years, all asymptomatic for hearing problems or ear disease, were evaluated with a hearing history questionnaire, otolaryngologic examination, and pure tone audiometry for the conventional (0.25 to 8 kHz) and extended high frequency (9 to 20 kHz) ranges. Hearing sensitivity was examined with respect to musician instrument type, years of playing, and orchestral stage position. Type of instrument played and position on the orchestral stage had no significant correlation with hearing loss.
TL;DR: Subjects involved in cooperative learning experiences performed higher on measures of interaction and interpersonal attraction between hearing and hearing-impaired students than did subjects involved in individualistic learning experiences.
Abstract: Cooperative and individualistic learning experiences were compared in terms of their effects on interaction and relationships between hearing and hearingimpaired students. Two contradictory hypotheses were tested—one stating that the effort required for hearing and hearing-impaired students to communicate would lead to frustration, withdrawal, exclusion, and rejection; the other stating that cooperative learning experiences would lead to cross-handicap interpersonal attraction regardless of communication difficulties. Thirty 3rd-grade students (20 hearing and 10 hearing impaired) were assigned to conditions on a stratified, random basis controlling for handicap, sex, and ability level. They participated in the study for 55 min a day for 15 instructional days. The results indicate that subjects involved in cooperative learning experiences performed higher on measures of interaction and interpersonal attraction between hearing and hearing-impaired students than did subjects involved in individualis...
TL;DR: In this article, the authors examined the effect of magnetic perturbations on fast ions in PDX discharges and found that when the current was rising slowly, a series of'minor' disruptions occurred, accompanied by decreases in β + li/2 and in the loop voltage, and increases in the plasma current.
Abstract: The current penetration phase of PDX discharges is examined. The Fast-Ion Diagnostic Experiment has been used to measure the temporal evolution of the central q (r/a < 0.4) and to show the effect of magnetic perturbations on fast ions. During plasma current penetration, a series of magnetic perturbations was observed in the plasma. When the plasma current was rising rapidly, the perturbations were accompanied by increases in β + li/2 and decreases in the loop voltage, suggesting a rapid penetration of the plasma current. When the plasma current was rising slowly, a series of 'minor' disruptions occurred. These were accompanied by decreases in β + li/2 and in the loop voltage, and increases in the plasma current. During this phase, current penetration may be enhanced by the change in the resistivity profile which accompanies the disruption.
TL;DR: In this paper, S-bridged complexes of the general formula {[Co 2 L 6 ]M} n+ with M = Co(III), Cd(II), Pb, Ni, Zn, and Hg(II) were prepared from [Co(2-aminoethanethiolate) 3 ] and the appropriate metal salt and 13 C NMR spectra were consistent with structures previously proposed for these species with 13 C chemical shifts dependent on the bridging metal ion.
Journal Article•
TL;DR: This article found that controversy, compared with concurrence seeking, resulted in higher-level reasoning reflected in the decision, greater epistemic curiosity and greater personal efficacy and commitment to the decision with no damage to the quality of the relationships among group members.
Abstract: : The effects of controversy and concurrence seeking were compared on effective decision making. Thirty-six students were randomly assigned to conditions and to groups of four within each condition. Subjects participated in a four-hour experimental session (two two-hour sessions two days apart), engaging in structured argumentation or avoiding disagreements while making a group decision, depending on the condition. The results indicate that controversy, compared with concurrence seeking, resulted in higher-level reasoning reflected in the decision, greater epistemic curiosity, and greater personal efficacy and commitment to the decision, with no damage to the quality of the relationships among group members. More orally active members were perceived as providing the most leadership. Additional keywords: Cooperation; Variables; Methodology; Agreements.
TL;DR: In this paper, a semi-empirical transport model was derived from global OH and L-mode confinement scalings and then applied to simulation of H-mode discharges, where radial diffusivities in the model depend on local density and pressure gradients and satisfy an appropriate dimensional constraint.
Abstract: The H-mode transition can lead to a rapid increase in tokamak plasma confinement. A semiempirical transport model was derived from global OH and L-mode confinement scalings and then applied to simulation of H-mode discharges. The radial diffusivities in the model depend on local density and pressure gradients and satisfy an appropriate dimensional constraint. Examples are shown of the application of this model and of similar models to the detailed simulation of two discharges which exhibit an H-mode transition. The models reproduce essential features of plasma confinement in the Ohmic heating and the low- and highconfinement phases of these discharges. In particular, the evolution of plasma energy content through the H-mode transition can be reproduced without any sudden or ad hoc modification of the plasma transport formulation.
TL;DR: Tangentially coinjected deuterium beam ions were accelerated from 82 up to 150 keV during a major-radius compression experiment in the tokamak fusion test reactor and the ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations.
Abstract: Tangentially coinjected deuterium beam ions were accelerated from 82 up to 150 keV during a major-radius compression experiment in the tokamak fusion test reactor. The ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations. In addition, the plasma rotation velocity was observed to rise during compression.
TL;DR: Mise en evidence d'instabilites electroniques dans la serie isoelectronique M II Mo 6 S 8 (M II =Co, Sr, Ba, Yb, Eu, Sn, Pb) and correlations entre ces instabilites and la nature des cations metalliques and avec les temperatures de transition supraconductrice as discussed by the authors.
Abstract: Mise en evidence d'instabilites electroniques dans la serie isoelectronique M II Mo 6 S 8 (M II =Co, Sr, Ba, Yb, Eu, Sn, Pb) et correlations entre ces instabilites et la nature des cations metalliques et avec les temperatures de transition supraconductrice
TL;DR: In this paper, a grating polychromator was used to measure the second-harmonic electron cyclotron emission from the low field side of the tokamak.
Abstract: First-harmonic electron cyclotron heating (ECH) experiments (PRF ≈ 80 kW, f 60 GHz) have been conducted on the Princeton Divertor Experiment (PDX) (R =137 cm, a ≈ 40 cm). Off-axis (≈ 4 cm) location of the resonance zone resulted in heating without sawtooth or m = 1 activity. However, heating with the resonance zone at the plasma centre caused very-large-amplitude sawteeth accompanied by strong m = 1 activity: ΔT/TMAX ≈ 0.41, sawtooth period ≈ 4 ms, m = 1 period 90 μs (11 kHz). This is the first time such intense MHD activity driven by low power (PRF/POH 0.35) ECH has been observed. (For both cases, there was no sawtooth activity in the Ohmic phase of the discharge before ECH.) At very low densities, there is a clear indication that a superthermal electron population is created during ECH. – The electron temperature evolution was monitored using a grating polychromator which measured second-harmonic electron cyclotron emission from the low field side of the tokamak. Interference from the high-power heating pulse on the broadband detectors in the grating instrument was eliminated by using a waveguide filter in the transmission line which brought the emission signal to the grating instrument.
TL;DR: A method employing stable isotope-labelled tracers and gas chromatograph-mass spectrometry (GC-MS) analysis has been used to measure the plasma clearance rates (PCR's) of androstenedione and testosterone in normal women and women with androgen abnormalities including hirsutism and polycystic ovary syndrome.
TL;DR: In additional experiments using isolated populations of T-cell subsets, T8 cells from MS patients who had low percentages of circulating T 8 cells were found to suppress PWM-induced IgG secretion by autologous cells to a similar extent as controls, suggesting that in vitro, T9 cells function normally in these patients.
TL;DR: The present status of the plasma confinement studies in the TFTR tokamak is described with emphasis on those with neutral beam injection (NBI), suggesting that the less-than-expected increase in stored energy with NBI is not due to problems of power delivery, but due to issues of confinement deterioration.
Abstract: The paper describes the present (end of February 1985) status of the plasma confinement studies in the TFTR tokamak with emphasis on those with neutral beam injection (NBI). Recent improvements in the device capabilities have substantially extended operating parameters: B /sub T/ increased to 4.0 T, I /sub p/ to 2.0 MA, injection power (P /sub b/ ) to /sup 5/ MW with H/sup 0/ or D/sup 0/ beams, n /sub e/ to 5 x 10/sup 19/ m/sup -3/ and Z /sub eff/ reduced to 1.4. With ohmic heating (OH) alone, the previously established scaling for gross energy confinement time (T /sub E/ /sup 0/ n /sub e/ q) has been confirmed at higher I /sub p/ and B /sub T/ , and the maximum T /sub E/ of 0.4 sec has been achieved. With NBI at P /sub b/ substantially (by factor > 2) higher than P /sub OH/ , excellent power and particle accountability have been established. This suggest that the less-than-expected increase in stored energy with NBI is not due to problems of power delivery, but due to problems of confinement deterioration. T /sub E/ is observed to scale approximately as I /sub p/ P /sub b/more » /sup 0.5/ (independent of n /sub e/ ), consistent with previous L-mode scalings. With NBI we have achieved the maximum T /sub E/ of 0.2 s and the maximum T /sub i/ (o) of 4.4 keV in the normal operating regime, and even higher T /sub i/ (o) in the energetic-ion regime with low-n /sub e/ and low I /sub p/ operation.« less