PECO - Artigos em revistas internacionais
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- Adult neurogenesis in the brain of the Mozambique tilapia, Oreochromis mossambicusPublication . Teles, Magda C; Sîrbulescu, Ruxandra F.; Wellbrock, Ursula M.; Oliveira, Rui Filipe; Zupanc, Günther K. H.Although the generation of new neurons in the adult nervous system ('adult neurogenesis') has been studied intensively in recent years, little is known about this phenomenon in non-mammalian vertebrates. Here, we examined the generation, migration, and differentiation of new neurons and glial cells in the Mozambique tilapia (Oreochromis mossambicus), a representative of one of the largest vertebrate taxonomic orders, the perciform fish. The vast majority of new cells in the brain are born in specific proliferation zones of the olfactory bulb; the dorsal and ventral telencephalon; the periventricular nucleus of the posterior tuberculum, optic tectum, and nucleus recessi lateralis of the diencephalon; and the valvula cerebelli, corpus cerebelli, and lobus caudalis of the cerebellum. As shown in the olfactory bulb and the lateral part of the valvula cerebelli, some of the young cells migrate from their site of origin to specific target areas. Labeling of mitotic cells with the thymidine analog 5-bromo-2'-deoxyuridine, combined with immunostaining against the neuron-specific marker protein Hu or against the astroglial marker glial fibrillary acidic protein demonstrated differentiation of the adult-born cells into both neurons and glia. Taken together, the present investigation supports the hypothesis that adult neurogenesis is an evolutionarily conserved vertebrate trait.
- Evaluation of the Financial Threat Scale (FTS) in four european, non-student samplesPublication . Marjanovic, Zdravko; Greenglass, Esther R.; Fiksenbaum, Lisa; Witte, Hans De; Santos, Francisco Garcia; Buchwald, Petra; Peiró, José María; Mañas, Miguel A.The Financial Threat Scale (FTS) was designed to assess levels of fear, uncertainty, and preoccupation about the stability and security of one’s finances. In previous research with Canadian university students, it was shown that the FTS was a psychometrically sound measure, associated with failing personal financial conditions, threat-related personality characteristics, and depreciated psychological health. The present investigation further examines the FTS in a diverse set of non-student European samples. Data were collected in four countries using a self-report questionnaire which included measures of ones’ financial situation, personality, and psychological health. Results were highly similar to the findings of the previous study. The FTS is unidimensional, reliable, and its validity was supported by moderate statistical relations with variables such as job insecurity, self-esteem, and emotional exhaustion. Importantly, financial threat was higher in countries that fared poorly in the recent financial crisis than countries that fared well, and it mediated the relation between economic hardship and psychological well-being. Implications for researchers are discussed.
- Beyond discounting : The tradeoff model of intertemporal choicePublication . Scholten, Marc; Read, DanielResearch on intertemporal judgments and choices between a smaller-sooner and a larger-later outcome has revealed many anomalies to the discounted-utility model. Attempts to account for these anomalies within the discounting paradigm have resulted in convoluted and psychologically opaque models. We therefore develop a new model of intertemporal choice, the tradeoff model, in which choice results from a tradeoff between the perceived time difference (interval) and the perceived outcome difference (compensation). This model is both more parsimonious and more intuitive than any rival discounting model of comparable scope. Moreover, it accurately describes archival data as well as data from a new experiment.
- Anomalies to Markowitz’s hypothesis and a prospect-theoretical interpretationPublication . Scholten, Marc; Read, DanielMarkowitz hypothesized a fourfold pattern of risk preferences, with risk aversion for large gains and small losses, but risk seeking for small gains and large losses. We test his hypothesis, and obtain two major results. One is the dispersion effect: A majority exhibits risk seeking and risk aversion for small and large gains, but disperses into five preference groups for small and large losses. There are the „Markowitzians‟ (risk aversion and risk seeking), the „non-Markowitzians‟ (risk seeking and risk aversion), the „Cautious‟ (global risk aversion), the „Audacious‟ (global risk seeking), and the „Wavering‟ (who exhibit no definite preference pattern). The other result is the migration effect: The composition of the preference groups changes across risk levels. More specifically, when going from high to moderate risk levels, the shares of the Markowitzians and the Cautious fall while the shares of the Audacious and the non-Markowitzians rise. We show that, if prospect theory accommodates the dispersion effect by allowing for heterogeneity in the elasticity of the value function and the elevation of the probability-weighing function, it correctly predicts the migration effect.
- Conflict-mediated choicePublication . Scholten, MarcResearch on behavioral decision making has demonstrated that preferences are affected by the set of options under consideration. Formal models offer an account of such choice-set effects on the basis of principles according to which the similarity of the options in the choice set has an effect on choice probabilities. Behavioral formulations are Tversky’s (1972) elimination- by-aspects (EBA) model, based on the principle of sequential elimination, and Tversky and Simonson’s (1993) componential context (CC) model, based on the principle of pairwise comparisons subject to loss aversion. While these principles are assumed to determine choice behavior, the conflict induced by the set of options under consideration is assumed to be merely a source of indeterminacy in choice behavior. This paper challenges past models by offering a behavioral account of choice-set effects according to which the effect of similarity on choice probabilities is mediated by conflict. A conflict-mediated choice (CMC) model is developed, its testable implications are derived, and its predictions are contrasted with those of the EBA model and the CC model. Specifically, it is described how, according to each of the three models, choice probabilities are affected by the similarity of the options in the choice set and how choice-set effects are moderated by the relative weight of the attributes along which the options are positioned. In two experimental studies, the CMC model offers an accurate account of observed choice-set effects and outperforms the alternative models.
- Lost and found : The information-processing model of advertising effectivenessPublication . Scholten, MarcThe objective of this study is to formulate a general framework for advertising research. The article provides a brief review of the hierarchy-of-effects para&gm, Petty and Cacioppo's (1983) elaboration-likelihood model (ELM), and McGuire's (1978) information-processing model (IPM). It is argued that the usefulness of the ELM for advertising research derives from its heuristic rather than integrative merits. It is further argued that the IMP, if appropriately revised on a number of critical aspects, incorporates rival proposals in the hierarchy-of-effects paradwn as well as the ELM and provides a sufficiently general framework for research on advertising effectiveness.
- Time and outcome framing in intertemporal tradeoffsPublication . Scholten, Marc; Read, DanielA robust anomaly in intertemporal choice is the delay–speedup asymmetry: Receipts are discounted more, and payments are discounted less, when delayed than when expedited over the same interval. We developed 2 versions of the tradeoff model (Scholten & Read, 2010) to address such situations, in which an outcome is expected at a given time but then its timing is changed. The outcome framing model generalizes the approach taken by the hyperbolic discounting model (Loewenstein & Prelec, 1992): Not obtaining a positive outcome when expected is a worse than expected state, to which people are over-responsive, or hypersensitive, and not incurring a negative outcome when expected is a better than expected state, to which people are under-responsive, or hyposensitive. The time framing model takes a new approach: Delaying a positive outcome or speeding up a negative one involves a loss of time to which people are hypersensitive, and speeding up a positive outcome or delaying a negative one involves a gain of time to which people are hyposensitive. We compare the models on their quantitative predictions of indifference data from matching and preference data from choice. The time framing model systematically outperforms the outcome framing model.
- Discounting by intervals: A generalized model of intertemporal choicePublication . Scholten, Marc; Read, DanielAccording to most models of intertemporal choice, an agent’s discount rate is a function of how far the outcomes are removed from the present, and nothing else. This view has been challenged by recent studies, which show that discount rates tend to be higher the closer the outcomes are to one another (subadditive discounting) and that this can give rise to intransitive intertemporal choice. We develop and test a generalized model of intertemporal choice, the Discounting By Intervals (DBI) model, according to which the discount rate is a function of both how far outcomes are removed from the present and how far the outcomes are removed from one another. The model addresses past challenges to other models, most of which it includes as special cases, as well as the new challenges presented in this paper: Our studies show that when the interval between outcomes is very short, discount rate tends to increase with interval length (superadditive discounting). In the discussion we place our model and evidence in a broader theoretical context.
- DRIFT: An analysis of outcome framing in intertemporal choicePublication . Read, Daniel; Frederick, Shane; Scholten, MarcPeople prefer to receive good outcomes immediately rather than wait, and they must be compensated for waiting. But what influences their decision about how much compensation is required for a given wait? To give a partial answer to this question, we develop the DRIFT model, a heuristic description of how framing influences intertemporal choice. We describe 4 experiments showing the implications of this model. In the experiments, we vary how the difference between a smaller sooner outcome and a larger later outcome is framed—either as total interest earned, as an interest rate, or as total amount earned (the conventional frame in studies of intertemporal choice)—and whether the larger later outcome is described as resulting from the investment of the smaller sooner one. These alternate frames have several effects. First, the investment language increases patience. Second, the explicit provision of the (otherwise implicit) experimental interest rate sharply reduces the magnitude effect. Correspondingly, we find that interest frames increase patience when the rewards are small, but they decrease patience when they are large. Third, the interest-rate frame induces somewhat greater discounting for longer time periods and, thus, reverses the common finding of “hyperbolic” discounting. Thus, many of the “stylized facts” implied by studies involving choices between a smaller sooner and a larger later amount are eliminated or reverse under alternate outcome frames.
- Tradeoffs between sequences: Weighing accumulated outcomes against outcome-adjusted delaysPublication . Read, Daniel; Scholten, MarcWe extend the recently proposed tradeoff model of intertemporal choice (Scholten & Read, 2010) from choices between pairs of single outcomes to pairwise choices involving two-outcome sequences. The core of our proposal is that choices between sequences are made by weighing accumulated outcomes against outcome-adjusted delays. Thus extended, the tradeoff model offers a unified account of recently discovered anomalies in pairwise choices involving two-outcome sequences, including (a) the hiddenzero effect, in which explicit reference to the zero outcomes of the options increases patience, (b) the front-end amount effect, in which the addition of a front-end amount to both options decreases patience, and (c) the mere token effect, in which the addition of an early outcome to both options increases patience. Not only does the extended tradeoff model accommodate these anomalies, it also correctly predicts (d) violations of independence, (e) a reversal of the front-end amount effect, (f) the effect of relocating the front-end amount to the back end of both options, and (g) a dependence of the “mere” token effect on the magnitude of the token. In quantitative analyses, the extended tradeoff model offers an accurate account of the data.