Effects of delta 9-THC on marijuana smoking, dose choice, and verbal report of drug liking.

The effects of delta 9-tetrahydrocannabinol content of marijuana on cigarette smoking, dose choice, and verbal report of drug "liking" by adult males living in a residential laboratory were investigated. Marijuana cigarettes were available during programmed intervals while subjects were engaged in recreational activities. The tetrahydrocannabinol content of the cigarettes remained constant each day, but was changed across days. Subjects provided written ratings of drug liking at the end of each day. In the first study, placebo or active (2.3% delta 9-tetrahydrocannabinol) marijuana cigarettes were available for 1-, 2-, or 3-day intervals at varying times of day. The number of cigarettes smoked was unrelated to tetrahydrocannabinol content, although verbal reports of drug liking were consistently higher when marijuana cigarettes containing tetrahydrocannabinol were smoked. In a second study, a choice procedure, consisting of four 3-day blocks of 2 sample days and 1 choice day, was used. On sampling days, subjects smoked cigarettes varying in tetrahydrocannabinol content (0.0, 2.0, and 3.5%, w/w); on choice days they were allowed to choose between the two previously sampled doses. The number of cigarettes was not consistently related to tetrahydrocannabinol content. Ratings of drug liking were increased when marijuana cigarettes contained tetrahydrocannabinol, but ratings of marijuana containing 2.0% and 3.5% of the compound were similar. In contrast, subjects consistently chose the 3.5% dose over either the 0.0% or 2.0% dose. Dose choice was more sensitive to tetrahydrocannabinol content than either reports of drug liking or numbers of cigarettes smoked.     

Synergistic effects of ethanol and cocaine on brain stimulation reward.

The effects of two widely abused drugs, ethanol and cocaine, were examined alone and in combination on intracranial reward processes. In agreement with previous research, higher doses of both cocaine and ethanol alone produced facilitation of behavior maintained by brain stimulation reward. Low intraperitoneal doses of ethanol and cocaine, which alone did not affect performance, were found to reduce stimulation reward threshold and modestly increase response rate. The enhancement of brain stimulation reward by the combination of ethanol and cocaine suggests that both drugs may produce their rewarding effects through common neuronal substrates and that they may potentiate the abuse of each other.     

Ratio versus difference comparators in choice.

Several theories in the learning literature describe decision rules for performance utilizing ratios and differences. The present paper analyzes rules for choice based on either delays to food, immediacies (the inverse of delays), or rates of food, combined factorially with a ratio or difference comparator. An experiment using the time-left procedure (Gibbon & Church, 1981) is reported with motivational differentials induced by unequal reinforcement durations. The preference results were compatible with a ratio-comparator decision rule, but not with decision rules based on differences. Differential reinforcement amounts were functionally equivalent to changes in delays to food. Under biased reinforcement, overall food rate was increased, but variance in preference was increased or decreased depending on which alternative was favored. This is a Weber law finding that is compatible with multiplicative, scalar sources of variance but incompatible with pacemaker rate changes proportional to food presentation rate.     

Tolerance to cocaine's rate-increasing effects upon repeated administration.

Four squirrel monkeys responded daily under a fixed-interval 5-min or 8-min schedule of food-pellet delivery. Cocaine (0.03 to 1.7 mg/kg) and saline were injected before occasional daily sessions (acute administration). Some doses of cocaine produced substantial overall increases in response rate for 3 of the subjects; effects were less substantial for the remaining subject, who exhibited modest increases in response rate early in the session and during the middle portion of the intervals. A dose that increased response rate when administered acutely was then administered before each session (chronic administration). Chronic administration resulted in a reduction in the increases in response rate seen under acute administration for all subjects.     

Capacity demands of automatic processes in semantic priming

Ben-Gurion University of the Negev, Beer Sheva, Israel In three experiments, we examined the effects of prime-target stimulus onset asynchrony (SOA) and the proportion of related primes and targets (relatedness proportion, or RP) on semantic priming when the prime was either named or was searched for a specific letter. In Experiment 1, with an RP of. 50, priming occurred at SOAs of 240 and 840 msec when the prime was named, but no priming was found at either SOA when the prime was searched for a letter. In Experiment 2 the RP was either. 20 or. 80, and the SOA was set at 1, 700 msec; priming again was found in both conditions when the prime was named, but only in the RP.80 condition when a letter search task was performed on the prime. In Experiment 3, both the proportion of related trials and SOA were varied; as in the previous experiments, no priming effects were found with the letter search task for either SOA in the RP.20 condition, but the priming effect was reinstated in the RP.80 condition. These results are discussed with respect to how limited capacity resources are allocated and how they influence semantic priming effects.     

An erotetic approach to explanation by specification

In earlier publications of the first author it was shown that intentional explanation of actions, functional explanation of biological traits and causal explanation of abnormal events share a common structure. They are called explanation by specification (of a goal, a biological function, an abnormal causal factor, respectively) as opposed to explanation by subsumption under a law. Explanation by specification is guided by a schematic train of thought, of which the argumentative steps not concerning questions were already shown to be logically valid (elementary) arguments.Independently, the second author developed a new, inferential approach to erotetic logic, the logic of questions. In this approach arguments resulting in questions, with declarative sentences and/or other questions as premises, are analyzed, and validity of such arguments is defined.In the present paper it is shown that all four kinds of erotetic argumentative steps occurring in the train of thought of explanation by specification are valid arguments in the sense of inferential erotetic logic. Hence, in view of the fact that the other argumentative steps were already shown to be valid, it may be concluded that the logical structure of explanation by specification can be as well-established as that of explanation by nomological subsumption. Moreover, explanation by specification provides some illustrations of the applicability of erotetic logic in everyday life and some empirical sciences.     

On the field aspect of Quantum fields

In this paper we contrast the idea of a field as a system with an infinite number of degrees of freedom with a recent alternative proposed by Paul Teller in Teller (1990). We show that, although our characterisation lacks the immediate appeal of Teller's, it has more success producing agreement with intuitive categorisations than his does. We go on to extend the distinction to Quantum Mechanics, explaining the important role that it plays there. Finally, we take some time to investigate the way in which strings are to be considered fields, and the important differences with scalar fields. Overall, we aim to show that many types of systems may be viewed as fields, and to point out significant distinctions amongst them, thereby expanding our understanding of what it is to fall in this category.Thanks to our anonymous referees for invaluable comments.     

Perfectionism and components of state and trait anxiety

The association between dimensions of perfectionism and state and trait anxiety was examined in three studies. Study 1 and Study 2 were correlational studies that investigated the link between dimensions of perfectionism (i.e., self-oriented, other-oriented, and socially prescribed perfectionism) and the Endler Multidimensional Anxiety Scales (EMAS). Taken together, the results indicated that self-oriented and socially prescribed perfectionsim are correlated significantly with both the cognitive-worry and autonomic-arousal components of state anxiety. As for the trait anxiety measures, self-oriented perfectionism was associated with the ambiguous and social evaluation facets in Study 1, and socially prescribed perfectionism was associated with the ambiguous and daily routines facets in Study 2. The purpose of Study 3 was to examine perfectionism and state anxiety under conditions of high versus low ego involvement. It was found that socially prescribed perfectionism was associated with higher state anxiety, but only in the high ego involvement condition. Self-oriented perfectionism was unrelated to state anxiety in either experimental condition. Overall, the findings indicate that socially prescribed perfectionism is the dimension linked most closely with components of state and trait anxiety, especially under conditions of ego threat. The results are discussed in terms of the need for an interactional approach to the study of the social aspects of both perfectionism and anxiety.     

Depression, self-esteem, and complex attributions for life problems

Past research has suggested that mild and moderate depression are associated with increased attributional processing and a tendency to make complex attributions involving two or more causes. The present research tested the hypothesis that depression and low self-esteem are associated with a tendency to make attributions to multiple causes when faced with life problems. The results were used to demonstrate that the tendency to make multiple attributions for specific life problems accounts for unique variance in depression and self-esteem scores, even after removing variance due to general attributional style. The findings are discussed with reference to the need for multidimensional models of attribution in depression and attributional retraining efforts to include an emphasis on individual differences in the number of multiple attributions made by people.     

Accuracy of memories from childhood and adolescence related to growth and size

The ability of middle-aged adults to recall their body size and events occurring up to 40 years earlier was assessed. Ninety-one subjects recalled their relative height, weight, and fatness during childhood, early adolescence and late adolescence. Accuracy of these memories was compared with the accuracy of current reports. The ability to accurately date benchmarks of their maturation such as menarche and year of maximal growth in height was also examined. Accuracy of reports did not decline uniformly over time. In general, reports of childhood physical characteristics were at least as accurate as reports of current characteristics; that is, they did not differ significantly from current reports. Males were less accurate in their reports of relative height and fatness during early adolescence and childhood. This project has been funded at least in part with federal funds from the U.S. Department of Agriculture, Agricultural Research Service under contract number 53-3K06-5-10. The contents of this article do not necessarily reflect the views or policies of the U.S. Department of Agriculture, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.