The authors explore the well-documented tendency for people to predict that they will finish tasks earlier than they actually do. Whereas previous research has tied this optimistic bias to the operation of specific cognitive processes, the present studies examine the interplay between motivation and cognition. Two studies supported the hypothesis that incentives to finish tasks quickly exacerbate the optimistic bias. An initial field study using a naturally occurring incentive manipulation demonstrated that individuals who expected an income tax refund were more (overly) optimistic in predicting when they would complete their income tax forms than those who did not expect a refund. A laboratory experiment using a word generation task replicated this general effect and identified mediating cognitive mechanisms: Monetary incentives for early completion led to optimistic predictions, increased attention to detailed future plans, and reduced attention to relevant past experiences.

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Symbolic responses are one of many issues attending contingent valuation studies. The problem is that many objects that are the subject of contingent valuation surveys can act as symbols for larger issues. In this paper, we want to compare the attitudes of residents of five communities with two different forest pests, jack pine budworm and gypsy moth. Jack pine budworm affects commercially important forests in Canada, while gypsy moth generally affects recreational areas and has less commercial significance. All of the respondents were asked about both insects; however, not all of the communities had direct experience with both insects. The purpose is to examine whether respondents would differentiate their willingness to pay for control mechanisms between these different defoliators. The implication is that all bugs are alike and generally noxious, a notion that would not necessarily sit well with resource managers who have to deal with insect outbreaks. Respondents did not differentiate strongly between insect control programs that would impact their community and those that would not. While not conclusive, the results do suggest symbolic responses to this particular issue. This is further evidence that willingness-to-pay results from contingent valuation studies need to be cautiously interpreted as pseudo market values.Les réponses symboliques sont l'une des nombreuses questions qui se rattachent aux enquêtes par la méthode des enchères. C'est qu'une bonne partie des objets visés dans ce type d'étude peuvent servir de symboles à des questions plus vastes. Nous voulions ici comparer les attitudes des habitants de cinq localités de l'Ontario à l'égard de deux insectes ravageurs des forêts, la tordeuse du pin gris et la spongieuse. Le premier s'attaque aux peuplements forestiers exploitables, tandis que le second intéresse en général les zones de loisirs mais revêt une importance commerciale moins forte. On interrogeait tous les enquêtés au sujet des deux insectes, même si les localités n'en n'avaient pas toutes subi l'expérience immédiate. On voulait savoir si leur disposition à assumer le coût de programmes de lutte était le même envers les deux défoliateurs, c'est-à-dire que pour eux tous les insectes seraient pareils et généralement nuisibles, une réaction qui ne ferait pas l'affaire des gestionnaires de ressources qui doivent faire face à des foyers d'infestation. De fait, les enquêtés ne faisaient pas beaucoup de différence entre les programmes de lutte qui concernaient leur localité et ceux qui ne la concernaient pas. Sans être concluants, les résultats font apparaître des réponses symboliques à cette question particulière et viennent renforcer le besoin de prudence lorsqu'on interprète les données de disposition à payer obtenues par la méthode des enchères comme pseudo-valeurs commerciales. ). There are numerous issues attending actual applications such as framing (context) effects (Mitchell and Carson 1989), embedding effects (i.e., valuations dependent on whether a good is valued as part of a larger goo...

Measurements of the absorption spectra associated with the vibrations of H - and D - ions in CaF 2 , SrF 2 and BaF 2 have been made in the region 1 to 17 μm . The most detailed investigation has been made in CaF 2 , where, in addition to the fundamental vibrational frequency, a second harmonic and two third harmonics of the fundamental frequency have been observed. The spectra have been assigned to the localized vibrations of isolated light ions on fluorine sites. The harmonics are seen because of anharmonic effects; to a good approximation the light ions can be considered to oscillate in an anharmonic tetrahedral potential well produced by a nearly static host lattice. W eak satellite lines are observed in the immediate vicinity of the fundamental vibrational lines due to the presence of small concentrations of H – and D – ions in other lattice configurations. Broad bands occur at displacements greater than about 100 cm-1 to higher and lower frequencies from the localized vibrational lines due to combined excitation of the localized mode and lattice band modes. The temperature-dependent intensity, shift and width of the localized vibrational lines have been measured. The presence of the broad side bands and the temperature-dependent effects arise from anharmonic interactions with the band modes of lattice vibration. A simple model of the band modes leads to very satisfactory agreement between theory and observed anharmonic effects for reasonable values of the anharmonic force constants which are regarded as parameters.