1,721,084 research outputs found
Multiple variable interval schedule behaviour in humans: effects of ethanol, mood, and reinforcer size on responding maintained by monetary reinforcement
No full textEthanol is an effective reinforcer but, in common with other drugs of abuse, it may derive some of its reinforcing properties from the effects it has on behaviour maintained by other reinforcers. However, any assessment of ethanol's hypothesized effect on behaviour maintained by other reinforcers must take into account the fact that ethanol may have multiple mechanisms of action. In order to address this problem the experiments reported herein used a procedure based upon Herrnstein's Matching Law which allowed joint assessment of subjects' motor capacity and reinforcer sensitivity. The effect of ethanol (0, 0.3, and 0.6 g/kg) on motor capacity and reinforcer sensitivity was assessed by studying behaviour maintained by monetary reinforcement. In the first experiment the procedure was validated by showing that the behaviour of subjects was sensitive to changes in reinforcer value and in the second experiment 0.6 g/kg ethanol reduced motor capacity but did not affect reinforcer sensitivity. As a secondary hypothesis we also studied the effect of mood on reinforcer sensitivity and motor capacity. It was found that lower mood scores (lower hedonic tone) were associated with reduced reinforcer sensitivity and that male subjects showed higher motor capacity than females. However, there was also a mood by sex interaction, which indicated that higher motor capacity in males was only found in the presence of lower mood scores. The results are discussed in relation to the mechanisms of ethanol's dopaminergic effects, interactions between ethanol and other drugs of abuse, and the changes in reinforcer sensitivity which are thought to occur in depression
Mood, cue and gender influences on motivation, craving and liking for alcohol in recreational drinkers
No full textThe effects of exposure to an alcohol-related cue (drinking low-alcohol beer) and a musical depression/elation mood induction procedure, on craving, motivation and liking for alcohol, were studied in male and female recreational drinkers. Alcohol craving was assessed using the multidimensional desires for alcohol questionnaire (DAQ), motivation for alcohol was assessed by performance on a progressive ratio (PR) task reinforced with small volumes (25 ml) of low-alcohol beer, and liking for the reinforcers earned in the PR task was assessed using a visual analogue scale. Consumption of a half-pint of low-alcohol beer increased alcohol craving in male subjects but had no effect or decreased craving in female subjects. Subsequent induction of a depressed mood increased craving scores, relative to elated or neutral mood groups, but these effects were confined to abstinent (non-cued) subjects, both male and female. Performance on the PR task correlated significantly with one of the four factors of the DAQ, negative reinforcement, and was increased by induction of a depressed mood in abstinent female and cued male subjects. Reinforcer liking was unchanged following mood induction in male subjects, but decreased in both groups of female subjects. To summarize, the cue of drinking low-alcohol beer increased alcohol craving in men but not in women, and induction of a depressed mood increased alcohol craving and motivation, but also decreased alcohol liking. These effects were present to different extents in different cue/gender subgroups, and were partially independen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Motivation for alcohol assessed by multiple variable interval schedule behaviour: effects of reward size and alcohol cues
No full textAltered motivation for drugs of abuse is a central feature of most definitions of drug dependence and the impact of drug-related cues on motivation is of current interest. However, since most studies of cue-reactivity have not used behavioural measures of motivation, their results are often difficult to interpret in motivational terms. In the current paper we describe two experiments in which a behavioural technique, based on multiple variable interval (VI) schedules of reinforcement, was used to study motivation for alcohol in human subjects. In both experiments, subjects attended for several sessions and, during each session, were exposed to a 6-ply VI schedule (values ranged from 1 to 720 s), during which they earned points that were later exchanged for a preferred beer or lager. In Experiment 1 the procedure was validated by showing that changes in the magnitude of reinforcement altered behaviour appropriately. In Experiment 2 we found evidence that the presence of an alcohol-related cue increased the value of alcohol rewards. The results are discussed with reference to a model for the behavioural effects of drug-related cues in triggering relapse and a number of problems we found in using the multiple variable interval schedule procedure
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