Effort is crucial for academic performance and varies by gender. However, it is not clear at what age nor under what circumstances gender differences in effort arise. Using behavioral measures of ...executive function from 799 fifth-grade students, we find no gender differences in cognitive effort in the absence of rewards. However, boys exert more effort than girls when materially incentivized. Adding a status incentive on top of material rewards does not further increase the gender gap. According to expectancy-value theory, the degree to which incentives moderate the gender effect may depend on ability. We find that while low-ability girls work as hard as high-ability girls when no incentives are present, low-ability boys tend to disengage from effortful tasks. High-ability girls increase effort more than low-ability girls when material incentives are added, and high-ability boys increase effort more than low-ability boys when status incentives are added.
•There is no gender gap in effort when performance is not rewarded.•Boys outwork girls when material incentives are in place.•The average gender gap does not widen when status incentives are added.•Effort is highest for high-ability boys under material and status incentives.•Effort is lowest among low-ability boys when no incentives are present.
Two cognitive processes have been explored that compensate for the limited information that can be perceived and remembered at any given moment. The first parsimonious cognitive process is object ...categorization. We naturally relate objects to their category, assume they share relevant category properties, often disregarding irrelevant characteristics. Another scene organizing mechanism is representing aspects of the visual world in terms of summary statistics. Spreading attention over a group of objects with some similarity, one perceives an ensemble representation of the group. Without encoding detailed information of individuals, observers process summary data concerning the group, including set mean for various features (from circle size to face expression). Just as categorization may include/depend on prototype and intercategory boundaries, so set perception includes property mean and range. We now explore common features of these processes. We previously investigated summary perception of low-level features with a rapid serial visual presentation (RSVP) paradigm and found that participants perceive both the mean and range extremes of stimulus sets, automatically, implicitly, and on-the-fly, for each RSVP sequence, independently. We now use the same experimental paradigm to test category representation of high-level objects. We find participants perceive categorical characteristics better than they code individual elements. We relate category prototype to set mean and same/different category to in/out-of-range elements, defining a direct parallel between low-level set perception and high-level categorization. The implicit effects of mean or prototype and set or category boundaries are very similar. We suggest that object categorization may share perceptual-computational mechanisms with set summary statistics perception.
The replicability of some scientific findings has recently been called into question. To contribute data about replicability in economics, we replicated 18 studies published in the American Economic ...Review and the Quarterly Journal of Economics between 2011 and 2014. All of these replications followed predefined analysis plans that were made publicly available beforehand, and they all have a statistical power of at least 90% to detect the original effect size at the 5% significance level. We found a significant effect in the same direction as in the original study for 11 replications (61%); on average, the replicated effect size is 66% of the original. The replicability rate varies between 67% and 78% for four additional replicability indicators, including a prediction market measure of peer beliefs.
Microplastics (<5 mm) have been found in many fish species, from most marine environments. However, the mechanisms underlying microplastic ingestion by fish are still unclear, although they are ...important to determine the pathway of microplastics along marine food webs. Here we conducted experiments in the laboratory to examine microplastic ingestion (capture and swallowing) and egestion by juveniles of the planktivorous palm ruff, Seriolella violacea (Centrolophidae). As expected, fish captured preferentially black microplastics, similar to food pellets, whereas microplastics of other colours (blue, translucent, and yellow) were mostly co-captured when floating close to food pellets. Microplastics captured without food were almost always spit out, and were only swallowed when they were mixed with food in the fish's mouth. Food probably produced a ‘gustatory trap’ that impeded the fish to discriminate and reject the microplastics. Most fish (93% of total) egested all the microplastics after 7 days, on average, and 49 days at most, substantially longer than food pellets (<2 days). No acute detrimental effects of microplastics on fish were observable, but potential sublethal effects of microplastics on the fish physiological and behavioural responses still need to be tested. This study highlights that visually-oriented planktivorous fish, many species of which are of commercial value and ecological importance within marine food webs, are susceptible to ingest microplastics resembling or floating close to their planktonic prey.
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•Fish captured preferentially microplastic similar to food pellets.•Microplastics were only swallowed when mixed with food in the fish's mouth.•Food produced a ‘gustatory trap’ that impedes fish to discriminate against microplastics.•Microplastics were egested after one week on average, and a maximum of 7 weeks.•Microplastics did not have notable acute deleterious effects on the fish.
Microplastic similarity to food, and food presence together with microplastics, influence the ingestion of microplastics by visually-oriented planktivorous fish.
Despite the renewed interest in the use of experimental designs in the fields of leadership and management over the past few decades, these designs are still relatively underutilized. Although there ...are several potential reasons for this, chief among them is misunderstanding the value of these designs. The purpose of this article is to review the role of laboratory, field, and quasi-experimental designs in management and leadership research. We first discuss the primary goals of experimental studies. Next, we examine the characteristics of experimental designs and how to distinguish laboratory, field, and quasi-experiments from one another and from non-experimental studies. Following these discussions, we provide examples of each type of experimental design and discuss their relative strengths and limitations. Finally, we discuss steps that researchers can take to increase the probability of having articles reporting experiments accepted by leadership and management journals.
Water ice is abundant in protoplanetary disks. Its sticking properties are therefore important during phases of collisional growth. In this work, we study the sticking and rolling of 1.1 mm ice ...grains at different temperatures. We find a strong increase in sticking between 175 and 200 K, which levels off at higher temperatures. In terms of surface energy this is an increase with a factor of 63.4, e.g., from γ = 0.0029 to γ = 0.19 J m−2, respectively. We also measured critical forces for inelastic rolling. The critical rolling distance is constant with a value of 0.19 mm. In view of planetesimal formation at low temperatures in protoplanetary disks, the surface energy is not larger than for silicate dust, and ice aggregation will share the same shortcomings. In general, water ice has no advantage over silicates for sticking, and collisional growth might not favor ice over silicates.
In this paper, we study the correlation between cheating in the lab and cheating in the field. We conduct a laboratory experiment using a variant of the Mind game (Jiang, 2013). Payoffs above a ...certain threshold are indicative of cheating behavior. Subjects are paid their earnings by bank transfer. A fraction of the subjects is deliberately paid more than their earnings. We send subjects a reminder e-mail stating their earnings and asking them if they have received their payment. We find a significant correlation of 0.31 between cheating in the lab and in the field. Subjects with higher payoffs in the Mind game are also less likely to report the overpayment. Our results speak to the lab-field generalizability of cheating behavior.
Soils underpin terrestrial ecosystem functions, but they face numerous anthropogenic pressures. Despite their crucial ecological role, we know little about how soils react to more than two ...environmental factors at a time. Here, we show experimentally that increasing the number of simultaneous global change factors (up to 10) caused increasing directional changes in soil properties, soil processes, and microbial communities, though there was greater uncertainty in predicting the magnitude of change. Our study provides a blueprint for addressing multifactor change with an efficient, broadly applicable experimental design for studying the impacts of global environmental change.
Safeguarding gene drive experiments in the laboratory Akbari, Omar S; Bellen, Hugo J; Bier, Ethan ...
Science (American Association for the Advancement of Science),
08/2015, Letnik:
349, Številka:
6251
Journal Article
Recenzirano
Odprti dostop
Gene drive systems promote the spread of genetic elements through populations by assuring they are inherited more often than Mendelian segregation would predict (see the figure). Natural examples of ...gene drive from Drosophila include sex-ratio meiotic drive, segregation distortion, and replicative transposition. Synthetic drive systems based on selective embryonic lethality or homing endonucleases have been described previously in Drosophila melanogaster (1-3), but they are difficult to build or are limited to transgenic populations. In contrast, RNAguided gene drives based on the CRISPR/Cas9 nuclease can, in principle, be constructed by any laboratory capable of making transgenic organisms (4). They have tremendous potential to address global problems in health, agriculture, and conservation, but their capacity to alter wild populations outside the laboratory demands caution (4-7). Just as researchers working with self-propagating pathogens must ensure that these agents do not escape to the outside world, scientists working in the laboratory with gene drive constructs are responsible for keeping them confined (4, 6, 7).
This study investigates how people provide public goods in a network formation game. In this game, players form a network through bilateral linking, with or without a link cost; the players then ...contribute to a public good, which can benefit both themselves and their direct neighbors. Theoretically, two equilibrium goods provision strategies exist: splitting and alternation. Efficient networks are conditioned on a goods provision strategy and are less dense when the link cost increases. Our laboratory experiment indicates that subjects predominantly converge to splitting instead of alternation and can often form efficient networks. Subjects form fewer links under a higher link cost and tend to form too many links.
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