Showing papers by "Hampshire College published in 1983"

Hierarchical control of rapid movement sequences.

Abstract: Are movement sequences executed in a hierarchically controlled fashion? We first state explicitly what such control would entail, and we observe that if a movement sequence is planned hierarchically, that does not imply that its execution is hierarchical. To find evidence for hierarchically controlled execution, we require subjects to perform memorized sequences of finger responses like those used in playing the piano. The error data we obtain are consistent with a hierarchical planning as well as execution model, but the interresponse-time data provide strong support for a hierarchical execution model. We consider three alternatives to the hierarchical execution model and reject them. We also consider the implications of our results for the role of timing in motor programs, the characteristics of motor buffers, and the relations between memory for symbolic and motor information. Language: en

The Movement Precuing Technique: Assumptions, Applications, and Extensions

Abstract: The movement precuing technique is designed to reveal the major information-processing steps that lead up to the execution of voluntary movements. The main idea in the technique is to supply the subject with partial information about the defining characteristics of a motor response and then observe how long it takes the subject to perform the response when its corresponding reaction signal is presented. On the assumption that the time to perform the response includes the time to specify those parameters that were not precued in advance, times to perform the response in different precue conditions can be used to find out whether its defining parameter values are specified in a fixed or variable order, serially or in parallel, etc. This chapter reviews the studies that have utilized the movement precuing technique. These studies have focused on aimed hand movements, finger movements, and aimed foot movements. A common finding of the studies is that the parameters of movements can be specified in a variable rather than fixed order and serially rather than in parallel, although some notable exceptions have been found. Much of the chapter is concerned with methodological variations of the precuing technique which a number of investigators have introduced.

The petrology of high‐MG dikes from the Beartooth Mountains, Montana: A search for the parent magma of the Stillwater Complex

Abstract: Six geochemically distinct groups of Precambrian high-Mg dikes have been examined to determine if any could have been a sample of or closely related to the parent magma of the Stillwater Complex. Only two groups have sufficiently magnesian olivine and orthopyroxene, but neither of these has sufficiently calcic plagioclase. In terms of major elements there appear to be only two distinct magma types: one has a high orthopyroxene component and is petrographically similar to noritic dikes and sills near the Great Dyke of Zimbabwe and the Bushveld Complex of South Africa; the other is similar to primitive tholeiites with higher plagioclase and diopside components than the first. All of the groups are enriched in light-REE and have unusually high K2O concentrations. Model calculations indicate that crustal contamination of fractionating komatiitic magmas is consistent with the major and trace element characteristics of the first magma type. Less extensive contamination of komatiitic magmas may produce the parental magmas of the large layered intrusions.

Evolution and Patriarchal Myths of Scarcity and Competition

Abstract: Nature, as depicted in biological science, is a man’s world. For researchers inevitably project the visions their imaginations, and the attitudes their life experiences make available,1 and most biologists have been men. A feminist task is to reconsider patriarchal images: to understand them as reflections of a male mentality; to consider whether they even answer any questions feminists wish to ask; and to remake the image of nature in metaphors conformable to women’s reality.