Infant Spinal Reflex-Testing Apparatus

Final report and team photo for Project 05 of ME450, Fall 2009 semester.Recently-developed equipment can test the presence and stability of spinal-level reflexes in the primary gait muscles of infants 2-10 months old. This baseline data can then assist in the assessment of developmental neuromotor deficits and the development of tailored interventions for infants born with disabilities such as spina bifida, cerebral palsy, and Down syndrome. The goal of this project is to redesign the apparatus used in these tests to be more adjustable and portable.Beverly Ulrich (Kinesiology, U of M)http://deepblue.lib.umich.edu/bitstream/2027.42/86199/1/ME450 Fall2009 Final Report - Project 05 - Infant Spinal Reflex-Testing Apparatus.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/86199/2/ME450 Fall2009 Team Photo - Project 05 - Infant Spinal Reflex-Testing Apparatus.jp

A Comparison of Four Models of Delay Discounting in Humans

The present study compared four prominent models of delay discounting: a one-parameter exponential decay, a one-parameter hyperbola (Mazur, 1987), a two-parameter hyperboloid in which the denominator is raised to a power (Green and Myerson, 2004), and a two-parameter hyperbola in which delay is raised to a power (Rachlin, 2006). Sixty-four college undergraduates made choices between hypothetical monetary rewards, one immediate and one delayed, and the fit of the four models to their data was assessed. All four equations accounted for a large proportion of the variance at both the group and the individual levels, but the exponents of both two-parameter models were significantly less than 1.0 at the group level, and frequently so at the individual level. Taken together, these results strongly suggest that more than one parameter is needed to accurately describe delay discounting by humans. Notably, both the Rachlin and the Green and Myerson models accounted for more than 99% of the variance at the group level and for 96% of the variance in the median individual. Because both models provide such good descriptions of the data, model selection will need to be based on other grounds

Focal points and bargaining

This is a contribution to the growing experimental literature on how trial-and-error adjustment processes can establish a convention for coordination on an equilibrium in a game. A simple bargaining game introduced by Nash is used for this purpose. Subjects are conditioned in different treatments to use four different bargaining solutions. The stability of the conditioning is then studied as the bargaining game is played over an extended period. The data obtained is unusually sharp. In the long run, the median subject behaves as though optimizing often down to a fraction of a penny. The results are therefore not supportive of the view that strategic considerations in such situations can be neglected in favor of a study of fairness norms. Indeed, the equilibrium actually achieved in a session turns out to be a very good predictor of what the median subject says is “fair” in the game after play is over.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45837/1/182_2005_Article_BF01240133.pd

Taxation and market power

"We analyze the incidence and welfare effects of unit sales taxes in experimental monopoly and Bertrand markets. We find, in line with economic theory, that firms with no market power are able to shift a high share of a tax burden on to consumers, independent of whether buyers are automated or human players. In monopoly markets, a monopolist bears a large share of the burden of a tax increase. With human buyers, however, this share is smaller than with automated buyers as the presence of human buyers constrains the pricing behavior of a monopolist." (author's abstract)"Dieser Artikel untersucht Inzidenz- und Wohlfahrtseffekte einer Mengensteuer in experimentellen Monopol- und Bertrand-Märkten. Im Einklang mit der ökonomischen Theorie sind Firmen ohne Marktmacht in der Lage, einen großen Anteil der Last einer Steuererhöhung an die Konsumenten weiterzugeben. Dies gilt unabhängig davon, ob die Käufer simuliert sind oder die Kaufentscheidungen durch reale Käufer getroffen werden. In Monopolmärkten trägt der Monopolist einen großen Anteil der Last einer Steuererhöhung. Werden die Kaufentscheidungen durch reale Käufer getroffen, ist dieser Anteil jedoch kleiner als mit simulierten Käufern, da reale Käufer im Experiment das Preissetzungsverhalten des Monopolisten einschränken." (Autorenreferat