Carnegie Mellon University

About: Carnegie Mellon University is a education organization based out in Pittsburgh, Pennsylvania, United States. It is known for research contribution in the topics: Population & Robot. The organization has 36317 authors who have published 104359 publications receiving 5975734 citations. The organization is also known as: CMU & Carnegie Mellon.

Social Ties and Susceptibility to the Common Cold

Abstract: Objective. —To examine the hypothesis that diverse ties to friends, family, work, and community are associated with increased host resistance to infection. Design. —After reporting the extent of participation in 12 types of social ties (eg, spouse, parent, friend, workmate, member of social group), subjects were given nasal drops containing 1 of 2 rhinoviruses and monitored for the development of a common cold. Setting. —Quarantine. Participants. —A total of 276 healthy volunteers, aged 18 to 55 years, neither seropositive for human immunodeficiency virus nor pregnant. Outcome Measures. —Colds (illness in the presence of a verified infection), mucus production, mucociliary clearance function, and amount of viral replication. Results. —In response to both viruses, those with more types of social ties were less susceptible to common colds, produced less mucus, were more effective in ciliary clearance of their nasal passages, and shed less virus. These relationships were unaltered by statistical controls for prechallenge virus-specific antibody, virus type, age, sex, season, body mass index, education, and race. Susceptibility to colds decreased in a dose-response manner with increased diversity of the social network. There was an adjusted relative risk of 4.2 comparing persons with fewest (1 to 3) to those with most (6 or more) types of social ties. Although smoking, poor sleep quality, alcohol abstinence, low dietary intake of vitamin C, elevated catecholamine levels, and being introverted were all associated with greater susceptibility to colds, they could only partially account for the relation between social network diversity and incidence of colds. Conclusions. —More diverse social networks were associated with greater resistance to upper respiratory illness.

The Red and the Black: Mental Accounting of Savings and Debt

Abstract: In the standard economic account of consumer behavior the cost of a purchase takes the form of a reduction in future utility when expenditures that otherwise could have been made are forgone. The reality of consumer hedonics is different. When people make purchases, they often experience an immediate pain of paying, which can undermine the pleasure derived from consumption. The ticking of the taxi meter, for example, reduces one's pleasure from the ride. We propose a "double-entry" mental accounting theory that describes the nature of these reciprocal interactions between the pleasure of consumption and the pain of paying and draws out their implications for consumer behavior and hedonics. A central assumption of the model, which we call prospective accounting, is that consumption that has already been paid for can be enjoyed as if it were free and that the pain associated with payments made prior to consumption but not after is buffered by thoughts of the benefits that the payments will finance. Another important concept is coupling, which refers to the degree to which consumption calls to mind thoughts of payment, and vice versa. Some financing methods, such as credit cards, tend to weaken coupling, whereas others, such as cash payment, produce tight coupling. Our model makes a variety of predictions that are at variance with economic formulations. Contrary to the standard prediction that people will finance purchases to minimize the present value of payments, our model predicts strong debt aversion-that they should prefer to prepay for consumption or to get paid for work after it is performed. Such pay-before sequences confer hedonic benefits because consumption can be enjoyed without thinking about the need to pay for it in the future. Likewise, when paying beforehand, the pain of paying is mitigated by thoughts of future consumption benefits. Contrary to the economic prediction that consumers should prefer to pay, at the margin, for what they consume, our model predicts that consumers will find it less painful to pay for, and hence will prefer, flat-rate pricing schemes such as unlimited Internet access at a fixed monthly price, even if it involves paying more for the same usage. Other predictions concern spending patterns with cash, charge, or credit cards, and preferences for the earmarking of purchases. We test these predictions in a series of surveys and in a conjoint-like analysis that pitted our double-entry mental accounting model against a standard discounting formulation and another benchmark that did not incorporate hedonic interactions between consumption and payments. Our model provides a better fit of the data for 60% of the subjects; the discounting formulation provides a better fit for only 29% of the subjects even when allowing for positive and negative discount rates. The pain of paying, we argue, plays an important role in consumer self-regulation, but is hedonically costly. From a hedonic perspective the ideal situation is one in which payments are tightly coupled to consumption so that paying evokes thoughts about the benefits being financed but consumption is decoupled from payments so that consumption does not evoke thoughts about payment. From an efficiency perspective, however, it is important for consumers to be aware of what they are paying for consumption. This creates a tension between hedonic efficiency and what we call decision efficiency. Various institutional arrangements, such as financing of public parks through taxes or usage fees, play into this tradeoff. A producer developing a pricing structure for their product or service should be aware of these two conflicting objectives, and should try to devise a structure that reconciles them.

Determinants of Risky Decision-Making Behavior: A Test of the Mediating Role of Risk Perceptions and Propensity

Abstract: The reported research examined the usefulness of placing risk propensity and risk perception in a more central role in models of risky decision making than has been done previously. Specifically, t...

Discovering objects and their location in images

Abstract: We seek to discover the object categories depicted in a set of unlabelled images. We achieve this using a model developed in the statistical text literature: probabilistic latent semantic analysis (pLSA). In text analysis, this is used to discover topics in a corpus using the bag-of-words document representation. Here we treat object categories as topics, so that an image containing instances of several categories is modeled as a mixture of topics. The model is applied to images by using a visual analogue of a word, formed by vector quantizing SIFT-like region descriptors. The topic discovery approach successfully translates to the visual domain: for a small set of objects, we show that both the object categories and their approximate spatial layout are found without supervision. Performance of this unsupervised method is compared to the supervised approach of Fergus et al. (2003) on a set of unseen images containing only one object per image. We also extend the bag-of-words vocabulary to include 'doublets' which encode spatially local co-occurring regions. It is demonstrated that this extended vocabulary gives a cleaner image segmentation. Finally, the classification and segmentation methods are applied to a set of images containing multiple objects per image. These results demonstrate that we can successfully build object class models from an unsupervised analysis of images.