STIMULUS (INSTRUCTIONAL) FADING DURING EXTINCTION OF SELF-INJURIOUS ESCAPE BEHAVIOR

Three individuals with developmental disabilities were exposed to a series of assessment conditions to identify the source of reinforcement for their self-injurious behavior. In each case, self-injury occurred most often in instructional (demand) situations containing a brief time-out from the task contingent on self-injury, indicating that the behavior was an escape response (i.e., maintained by negative reinforcement). Treatment was implemented in a multiple baseline across subjects design and consisted of extinction (prevention of escape) plus instructional fading (initial elimination of instructions followed by their gradual reintroduction). Results showed that the combined treatment produced immediate and large reductions in self-injury that were maintained as the frequency of instructions was increased across sessions to match the original baseline rate of presentation. Results of a component analysis conducted with 1 subject suggested that stimulus fading accelerated the behavior-reducing effects of extinction.     

THE CASE FOR THE PHILOSOPHY OF CHEMISTRY

The philosophy of chemistry has been sadly neglected by most contempory literature in the philosophy of science. This paper argues that this neglect has been unfortunate and that there is much to be learned from paying greater philosophical attention to the set of issues defined by the philosophy of chemistry. The potential contribution of this field to such current topics as reduction, laws, explanation, and supervenience is explored, as are possible applications of insights gained by such study to the philosophy of mind and the philosophy of social science.     

Regendering the U.S. Abortion Debate

This paper originated in a conference presentation with my colleague Michael Tooley, at which we were both asked to re-evaluate articles about abortion that each of us had written over twenty years earlier. While Tooley and I both contended that abortion should be legally unrestricted, there were striking differences in the style and content of our respective arguments. Contemplating these differences has reinforced my own belief in the importance of emphasizing the centrality of gender when discussing abortion. Since gender as we know it is a system of dominance as well as difference (MacKinnon 1987), I take this to mean that contemporary discussions of abortion must address the relationship between abortion access and the social status of women. My early article addressed this relationship to some extent, but the present paper will raise a number of additional gender issues that the early article did not mention.     

On the young child's comparison of sets

When asked to make comparisons between sets of objects, 4-year-old children succeed when the comparison questions are symmetrical with respect to the referential status of their terms. Thus questions that request the comparison of set with set, or subset with subset (both within and between sets), are answered correctly. However, when the comparison questions are referentially asymmetrical, calling for the comparison of set with subset, either within or between sets, young children typically fail to complete such tasks successfully. In such cases, what comparisons young children arrive at is established, how they arrive at them is described, and why they respond in the ways that they do is discussed.     

Gait patterns during free choice ladder ascents

Twenty two male subjects each performed five climbing trials of a portable straight ladder. Each subject was instructed to ascend the ladder at a “comfortable” pace using only the rungs for support. For the first, third and fifth trials, the temporal and movement characteristics of the performances were recorded using capacitive touch sensors mounted on each of the rungs and high-speed cinematographical techniques. The results revealed little evidence to suggest a preferred climbing gait. The two most commonly utilized methods of ascent for all trials were the lateral and four-beat lateral gaits. Only 31.8% of the subjects adopted the same gait pattern during each of the three trials. The temporal characteristics of each gait pattern showed a relatively longer time for each segment contact phase than for the corresponding airborne phase. The shortest average period was found for the four-beat diagonal gait followed, in order, by the lateral, diagonal and four beat lateral gaits. Variability measures assumed the same ranking in reverse order with the four-beat diagonal gait producing the most variable period times.