Human genome research in an interdependent world.

This has been the year of agenda-setting conferences for the ambitious ELSI (ethical, legal and social issues) program of the Human Genome Project (HGP). But of the dozen or more major meetings of this sort held across the country, the one held at the National Institutes of Health (NIH) in Bethesda, MD, June 2-4, 1991, was distinctive in several respects. As its name implies, "Human Genome Research in an Interdependent World" was a global look at the issues raised by gene mapping and sequencing. Unlike previous conferences, however, this meeting looked beyond a comparative analysis of clinical and domestic legal issues, and concentrated on topics that may require responses on a truly international level if they are to be successfully resolved....[Capron served as general chairman of the conference]     

Type A behavior and reminiscence in college undergraduates

This study represents the first empirical test of Friedman and Ulmer's (1984. Treating Type A behavior and your heart. New York: Fawcett) clinical observation that deficits in the capacity to reminisce about pleasant past events are among the most pervasive and dysfunctional correlates of Type A behavior. Type A (N = 79) and B (N = 109) college undergraduates completed a questionnaire assessing the frequency, content, style, and consequences of their reminiscence about positive past experiences. Findings supported two hypotheses: relative to Type Bs, Type As were less likely to report that they consciously look back on positive events after these events are over in order to store details for later recall, and were more likely to report that they typically reminisce about past achievements. Contradicting Friedman and Ulmer's observations, however, there were no significant A/B differences in the reported frequency, style, or consequences of recalling positive memories. The findings are discussed in terms of components of Type A behavior, such as competitive achievement-striving and self-esteem enhancement, that may make Type As (a) less likely to store, but not to recall, positive memories and (b) particularly likely to reminisce about personal accomplishments. Plausible reasons for the relative lack of support for Friedman and Ulmer's hypotheses are discussed in the context of directions for future research.     

More on parts in object concepts: Response to Tversky and Hemenway

This articleresponds to the comments ofTversky and Hemenway (1991), who criticized the logic, stimuli, and data analysis of Murphy (1991). It is argued here that their objections do not mitigate the conclusions drawn by Murphy. In particular, the objection that the stimuli were not natural enough to reveal differences between category levels seems to presuppose an answer to the question under investigation. However, further experimentation with other stimuli might resolve this issue empirically.     

Parts in object concepts: Experiments with artificial categories

Previous research has demonstrated that basic-level categories are associated with the parts of objects. Five experiments were conducted to investigate whether this correlation is caused by a psychological principle that requires basic concepts to have common parts. This hypothesis was investigated in the experiments by separating part and nonpart information in artificial categories. Basic-level structure was measured in two ways: as the level with the highest ratio of within-category similarity to between-category similarity, and as the level with the fastest categorization time in an object-identification task. The results revealed that basic-level structure could be found in categories that did not have parts in common. Furthermore, nonpart information, such as size, color, and texture, could both enhance the basic level and eliminate the basic-level advantage, depending on whether the nonpart information was consistent with or contradicted the part information. These results suggest that, psychologically, parts are neither necessary nor sufficient to form a basic level.     

Effects of short-term isolation on the locomotor activity of the angelfish (Pterophyllum scalare).

Two experiments were conducted to test in angelfish (Pterophyllum scalare) some implications of Gallup and Suarez's (1980) ethological model of open-field behavior and to differentiate between the initial locomotor effects of a novel environment and those of isolation per se. Juveniles placed alone in a novel environment initially showed increased locomotion compared with their previous level when kept as a group and with that of fish placed in the novel environment in groups of three and five. When placed alone in a novel tank, individuals that had already been isolated for 10 days moved about less than those that had been isolated for 4 days. During isolation, angelfish significantly reduced activity to a minimum after 3 to 4 days, and after 10 days the level was still lower than in the group situation. The results suggest that, in addition to birds and rodents, Gallup and Suarez's model is applicable to fish and may account for the effects of longer exposure to a novel environment.     

The effects of isolation rearing on behavioural inhibition in the rat

The possibility that isolation-rearing in the rat affects the development of inhibitory mechanisms was studied in a series of experiments. It was found that socially-isolated rats were (1) slower to learn both a lever-panel alternation, and a two-lever alternation schedule of reinforcement, (2) more persistent than controls in pressing a lever for food when a supply of identical “free food” was introduced into the operant chamber, but (3) similar to control rats in their response to preloading with food, a procedure which inhibited lever pressing to the same extent in the two groups. Finally, it was shown in a separate experiment that the effects of increased food deprivation on lever pressing in the presence of free food were qualitatively different from the effects of social isolation, and therefore the social/isolate difference cannot be interpreted as motivational. The possible contributions of neophobia to the difference are discussed. It is concluded that isolates may well suffer from a disinhibitory defect, but that there are probably other effects of isolation in addition.     

Effects of random reinforcement sequences

Rats were exposed to a random sequence of reinforcement on two levers, such that there was no way to predict from the previous reinforcement which lever would deliver reinforcement next. The rats showed a tendency to repeat the choice that had just produced reinforcement, despite the absence of an overall contingency that differentially reinforced such repetition. However, this tendency decreased with continued exposure to the schedule. Runs of successive reinforcements on a lever increased the probability of pressing that lever, but only slightly, and only in the earlier phases of training. The more quickly a press was made after reinforcement the more likely it was to be on the lever that had delivered that reinforcement. Repetition of choice followed by reinforcement should be viewed as a naturally occurring behavior in the rat, but not necessarily as a behavior that will continue without differential reinforcement of repetition.