Home About us Contact
|
Home About us Contact | ||
|
|
||
Replicated Experiment (replicated + experiment)
Selected AbstractsExperimental Tests of Normative Group Influence and Representation Effects in Computer-Mediated CommunicationHUMAN COMMUNICATION RESEARCH, Issue 3 2002When Interacting Via Computers Differs From Interacting With Computers Two experiments addressed the questions of if and how normative social influence operates in anonymous computer-mediated communication (CMC) and human-computer interaction (HCI). In Experiment 1, a 2 (public response vs. private response) × 2 (one interactant vs. four interactants) × 3 (textbox vs. stick figure vs. animated character) mixed-design experiment (N = 72), we investigated how conformity pressure operates in a simulated CMC setting. Each participant was asked to make a decision in hypothetical social dilemmas after being presented with a unanimous opinion by other (ostensible) participants. The experiment examined how the visual representation of interaction partners on the screen moderates this social influence process. Group conformity effects were shown to be more salient when the participant's responses were allegedly seen by others, compared to when the responses were given in private. In addition, participants attributed greater competence, social attractiveness, and trustworthiness to partners represented by anthropomorphic characters than those represented by textboxes or stick figures. Experiment 2 replicated Experiment 1, replacing interaction with a computer(s) rather than (ostensible) people, to create an interaction setting in which no normative pressure was expected to occur. The perception of interaction partner (human vs. computer) moderated the group conformity effect such that people expressed greater public agreement with human partners than with computers. No such difference was found for the private expression of opinion. As expected, the number of computer agents did not affect participants' opinions whether the responses were given in private or in public, while visual representation had a significant impact on both conformity measures and source perception variables. [source] Memory of children's faces by adults: Appearance does matter,APPLIED COGNITIVE PSYCHOLOGY, Issue 7 2009Vicki Silvers Gier Accurately detecting faces of children when their appearance has been altered is especially important in recognizing abducted or missing child. Face recognition studies have focussed on recognizing the adult perpetrator; however, there is lack of research on recognizing a child's face under different appearances. Two studies were conducted to determine what type of photos may increase recognition of missing children. In Experiment 1 participants were shown pictures of children's faces in a study phase in which their faces were either dirtied with negative affect or clean with positive affect, followed by a recognition phase. Accuracy and confidence were higher when the face at recognition was the same type as in the study phase. Experiment 2 replicated Experiment 1, adding four delay conditions: 10-minute interval (10-MI), 3, 6 or 12 week. Accuracy and confidence decreased over time and we again found a significant interaction between face at study and face at recognition. Copyright © 2008 John Wiley & Sons, Ltd. [source] Probabilistically Valid Inference of Covariation From a Single x,y Observation When Univariate Characteristics Are KnownCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 2 2009Michael E. Doherty Abstract Participants were asked to draw inferences about correlation from single x,y observations. In Experiment 1 statistically sophisticated participants were given the univariate characteristics of distributions of x and y and asked to infer whether a single x, y observation came from a correlated or an uncorrelated population. In Experiment 2, students with a variety of statistical backgrounds assigned posterior probabilities to five possible populations based on single x, y observations, again given knowledge of the univariate statistics. In Experiment 3, statistically naïve participants were given a problem analogous to that given in Experiment 1, framed verbally. Experiment 4 replicated Experiment 3 but added an "impossible to determine" response option. Models that rely on computing sample correlations make no predictions about these investigations. From a Bayesian perspective, participants' inferences in all four experiments tended to make probabilistically valid inferences as long as the single datum was directional. The results are discussed in light of the Brunswikian notion of vicarious functioning. [source] Prospects for conserving biodiversity in Amazonian extractive reservesECOLOGY LETTERS, Issue 3 2002Susan M. Moegenburg Abstract Non-timber forest product (NTFP) extraction is a popular alternative to timber extraction that figures prominently in efforts to utilize tropical forests sustainably. But the ability to conserve biodiversity through NTFP management, particularly in extractive reserves in Amazonia, has remained untested. We found that intensive management of Euterpe oleracea (Palmae) fruit, one of the most important extractive products in the Amazon, has substantial impacts on biodiversity, whereas moderate management does not. We mimicked traditional levels of fruit harvest in a replicated experiment over one fruiting season. High-intensity harvest (75% of fruits removed) reduced avian frugivore species diversity by 22%. Low-intensity harvest (40% of fruits removed), however, had no effect on diversity. On a larger scale, we found that forests with enriched densities of E. oleracea supported more fruit-eating birds but fewer non fruit-eating birds than non-enriched forests. Taken together, these results suggest that intensive NTFP management to meet market demands may trigger substantial ecological impacts, at least at the level of our study. E. oleracea harvest should be limited where conservation of biodiversity is a goal. [source] Long-term enhancement of agricultural production by restoration of biodiversityJOURNAL OF APPLIED ECOLOGY, Issue 1 2007JAMES M. BULLOCK Summary 1Experimental manipulations have shown positive impacts of increased species richness on ecosystem productivity, but there remain some questions about this relationship. First, most studies last < 4 years, which raises issues about whether diversity,productivity relationships are maintained in mature communities. Secondly, the conservation relevance of many studies is debatable. We addressed both issues using long-term experimental studies of the agriculturally relevant hay yield of recreated species-rich grasslands. 2Grasslands were recreated within replicated experiments in ex-arable fields at two sites in southern England by using either species-poor or species-rich seed mixtures. The species-poor mixture comprised seven grasses as recommended for grassland creation in English agri-environment schemes. The species-rich mixture comprised 11 grasses and 28 forbs and was designed to recreate a typical southern English hay meadow. 3After 8 years the plots sown with species-rich mixtures resembled target diverse community types. The plots sown with species-poor mixtures had been colonized by a number of forbs but had lower numbers of grasses, legumes and other forbs than the species-rich plots. Increased hay yield of the species-rich plots in the first years of the experiments have been described in an earlier paper, and these differences were maintained after 8 years. 4In the eighth year the species-rich plots had an average 43% higher hay yield than the species-poor plots. Regression analysis showed that the variation in hay yield was related to differences in the number of non-leguminous forbs and showed no relation to grass or legume numbers. This suggests increased hay yield is an effect of the greater range of life forms exhibited by forbs rather than a simple fertilizing effect of legumes. 5The nitrogen content and phosphorus content of the hay showed complex treatment effects over time. However, the nutritional value of the hay was above the minimum requirements for livestock. 6Synthesis and applications. The aims of conservationists and farmers can often be in conflict. This study has shown that the recreation of diverse grasslands of conservation value can have a positive impact on hay yield, which benefits the farm business, and this is repeated across differing sites. Because the effect is maintained over time, farm income will be increased in the long term. [source] In vitro micro-tuber initiation and dormancy in yamANNALS OF APPLIED BIOLOGY, Issue 2 2010E.I. Hamadina Dormancy is a mechanism that regulates the timing of sprouting (germination) of affected plant parts as well as ensures that the food quality of edible parts is maintained in storage until the following growing season. In yam, however, little is known about the control of tuber initiation or tuber dormancy. The objective of this study was to determine the effects of selected plant growth regulators (PGRs) on tuber initiation and dormancy, using an in vitro system. In two replicated experiments, 2-chloroethylphosphonic acid (ethephon, an ethylene source), abscisic acid (ABA) and gibberellin (GA3) , and their inhibitors silver nitrate, fluridone and 2-chloroethyl-trimethylammonium chloride, respectively , were added at two concentrations to the culture medium prior to explant culture. Dates of micro-tuber initiation and sprouting (end of dormancy) and tuber number were recorded. In the control (no PGR) in Experiment 1, micro-tubers were initiated at the base of the stem after 176 days and sprouted 235 days later, that is 411 days after culturing. Most PGR treatments had only small effects (±30 days) on the duration of dormancy and the time of micro-tuber initiation. However, in GA3 micro-tuber initiation occurred after 76 days, about 100 days earlier than in the control, whereas fluridone affected the position of micro-tubers and duration of dormancy. With fluridone treatments, tubers were found at the base of the stem (normal position) and on lower and upper nodes. Lower node tubers sprouted within 225 days of culturing compared with about 420 days after culturing at other nodal positions and in other PGR treatments. These data suggest an important role for ABA and gibberellic acid in yam micro-tuber initiation and the induction of dormancy. [source] The effect of restoration techniques on non-target species: case studies in moorland ecosystemsAPPLIED VEGETATION SCIENCE, Issue 1 2009R.J. Mitchell Abstract Questions: What is the impact on non-target species of restoration methods to establish Calluna vulgaris on grass-dominated moorlands? Location: A Nardus stricta -dominated moorland in Wales and a Molinia caerulea -dominated moorland in Northern England, UK. Methods: Two replicated experiments were established on grass-dominated moorlands. The treatments comprised disturbance (rotavation and trampling by animals), addition of Calluna seed, and three different grazing regimes, together with a no grazing control. Results: The creation of bare ground and addition of seed increased the establishment of the desired dominant shrub, Calluna vulgaris. In the Nardus sward, rotavation and trampling were equally successful in establishing Calluna, but rotavation was more successful in the Molinia sward. Rotavation inhibited the growth of competitive grass species better than trampling. However, the disturbance techniques were detrimental to other components of the plant community, causing a decline in the cover of desirable species such as Vaccinium myrtillus and other dwarf shrub species and a small increase in the occurrence of undesirable species such as Juncus effusus. Grazing also controlled competitive grass species: Festuca ovina decreased in cover at a grazing intensity of 1.5 ewes/ha; Molinia caerulea and Agrostis spp. declined when cattle were included in the grazing regime, but increased in cover when ungrazed or when grazed at 1.5 ewes/ha. Conclusions: When restoration concentrates on the establishment of one or a few species, it is important to monitor how the techniques used affect the rest of the plant community , particularly with regard to losses of desirable species or increases in undesirable species. [source] | |||||||||||||