How incidental values from the environment affect decisions about money, risk, and delay

How different are £0.50 and £1.50, or "a small chance" and "a good chance", or "three months" and "nine months"? Our experiments show that people behave as if these differences alter after incidental everyday experiences. Preference for a £1.50 lottery rather than a £0.50 lottery was stronger after exposure to intermediate supermarket prices. Preference for "a good chance" of winning rather than "a small chance" was stronger after predicting intermediate probabilities of rain. Preference for consumption in "three month" rather than "nine months" was stronger after planning for an intermediate birthday. These fluctuations offer a direct challenge to economic accounts which translate monies, risks, and delays into subjective equivalents by stable functions. The decision by sampling model, in which subjective values are rank positions constructed from comparisons with samples of monies, probabilities, or delays, predicts these effects and indicates a primary role for sampling in decision making

Does wage rank affect employees' well-being?

How do workers make wage comparisons? Both an experimental study and an analysis of 16,000 British employees are reported. Satisfaction and well-being levels are shown to depend on more than simple relative pay. They depend upon the ordinal rank of an individual's wage within a comparison group. “Rank” itself thus seems to matter to human beings. Moreover, consistent with psychological theory, quits in a workplace are correlated with pay distribution skewness

On the origin of utility, weighting, and discounting functions: How they get their shapes and how to change their shapes

We present a theoretical account of the origin of the shapes of utility, probability weighting, and temporal discounting functions. In an experimental test of the theory, we systematically change the shape of revealed utility, weighting, and discounting functions by manipulating the distribution of monies, probabilities, and delays in the choices used to elicit them. The data demonstrate that there is no stable mapping between attribute values and their subjective equivalents. Expected and discounted utility theories, and also their descendants such as prospect theory and hyperbolic discounting theory, simply assert stable mappings to describe choice data and offer no account of the instability we find. We explain where the shape of the mapping comes from and, in describing the mechanism by which people choose, explain why the shape depends on the distribution of gains, losses, risks, and delays in the environment

Response vs. Perception

Three experiments were conducted in which college students read, and then attempted to match, a series of written descriptive passages with the referent photographs on which they were based; the photographs sho wed the face of an actor, representing a variety of emotional expressions. In Experiment I, subjects provided with a series of context passages depicting a narrow range of emotions (neither pleasant nor unpleasant) chose “matches” having more extreme pleasantness values than did subjects provided with context passages depicting a wide range of descriptions on the pleasantness dimension when responding to test descriptions embedded within the context series. In Experiments II and III, contrast effects were obtained; subjects who had read mostly unpleasant context passages chose more pleasant referents in response to neutral test descriptions than did those who had read mostly pleasant descriptions. The results of all three experiments suggested that these effects were mediated in large part by a response bias, the tendency to use each response alternative with roughly equal frequency. In Experiments II and III, there was suggestive evidence for the possibility that a more central (or perceptual) mechanism may also have contributed to the observed results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45367/1/11031_2004_Article_BF00992590.pd

Isolated Grauer's gorilla populations differ in diet and gut microbiome

The animal gut microbiome has been implicated in a number of key biological processes, ranging from digestion to behavior, and has also been suggested to facilitate local adaptation. Yet studies in wild animals rarely compare multiple populations that differ ecologically, which is the level at which local adaptation may occur. Further, few studies simultaneously characterize diet and gut microbiome from the same sample, despite their likely interdependence. Here, we investigate the interplay between diet and gut microbiome in three geographically isolated populations of the critically endangered Grauer's gorilla, which we show to be genetically differentiated. We find population- and social group-specific dietary and gut microbial profiles and co-variation between diet and gut microbiome, despite the presence of core microbial taxa. There was no detectable effect of age, and only marginal effects of sex and genetic relatedness on the microbiome. Diet differed considerably across populations, with the high-altitude population consuming a lower diversity of plants compared to low-altitude populations, consistent with plant availability constraining diet. The observed pattern of covariation between diet and gut microbiome is likely a result of long-term social and environmental factors. Our study suggests that the gut microbiome is sufficiently plastic to support flexible food selection and hence contribute to local adaptation