Role of conditioned reinforcers in the initiation,maintenance and extinction of drug-seeking behavior

The development of a secondary reinforcer as a result of associating a neutral stimulus (buzzer) with intravenous (IV) doses of morphine was studied in rats. Secondary reinforcement developed in the absence of physical dependence and followed the association of the stimulus with either response-contingent or non-contingent injections of morphine. Strength of the conditioned reinforcer, measured in terms of responding on a lever for the stimulus plus infusion of saline solution, was proportional to the unit dosage of morphine employed in pairings of buzzer and drug. When extinction of the lever-press response for IV morphine was conducted (by substituting saline for morphine solution) in the absence of the conditioned reinforcing stimulus, it was seen later that the stimulus could still elicit lever responses, until it too had been present for a sufficient interval of non-reinforced responding. Similarly, extinction of the response for morphine by blocking its action with naloxone in the absence of the stimulus did not eliminate the conditioned reinforcement. Another study showed that a passive, subcutaneous (SC) dose of morphine served to maintain lever-pressing on a contingency of buzzer plus sahne infusion. Furthermore, the stimuli resulting from the presence of morphine (after a SC injection) were able to reinstate the lever-responding with only the buzzer-saline contingency when such responses had previously been extinguished. Moreover, it was shown thatd-amphetamine could restore responding under the same conditions, and that morphine could also do so for rats in which the primary reinforcer had beend-amphetamine. It is suggested that animal data such as these show that procedures designed for the elimination of human drug-taking behavior must take into account secondary reinforcers as well as the primary reinforcer(s).     

Demographic influences in sensation seeking and expressions of sensation seeking in religion, smoking and driving habits

A large sample of readers of a popular psychology magazine took the Sensation Seeking Scale (form V) and filled out a personal data form. The information in the data form was used to examine the relationship between SSS scores and demographic and experience variables. Sex and age showed strong relationships with the SSS. Education and occupation of the subjects and their parents showed lesser relationships with the SSS and primarily in females. Non-believers in conventional religion and infrequent church-goers had higher SSS scores than those who identify with such religions and attend church regularly. Smokers had higher scores than non-smokers although the relationship with amount of smoking was not a linear one. Driving habits of speeding related strongly to sensation seeking in a linear fashion.     

How much help do repeated presentations give to recognition processes?

A recent experiment by Haber and Hershenson (1965) had shown that in a recognition task one long look at a stimulus was always superior to two or more shorter looks summing to the same total presentation time. In order to explore this more fully and to account for opposite results in a different type of recognition task, as well as in a serial learning task, an improved replication of the earlier study was carried out using very short durations and single letters as stimuli. The same non-reciprocity was found, again strongly favoring duration over repetition as a determinant of clarity of a percept, even though repetition alone was also shown to be a significant independent variable. As a subsidiary finding, an error analysis showed that when a letter was misnamed it was nearly always confused with one that looked like it rather than one that sounded like it. Some discussion was offered as to the role of an auditory information storage in low memory load tasks such as this one, as well as some general implications for information processing analyses of the non-reciprocity of duration and repetition.     

Auditory agnosia for speech (“pure word-deafness”): A historical review with current implications

A historical review of thought about the existence, clinical presentation, and mechanism of auditory agnosia for speech is presented. Implications of recent contributions which shed more light on this syndrome are discussed.     

Increases in rewards promote flexible behavior

Offering reward for performance can motivate people to perform a task better, but better preparation for one task usually means decreased flexibility to perform different tasks. In six experiments in which reward varied between low and high levels, we found that reward can encourage people to prepare more flexibly for different tasks, but only as it increased from the level on the previous trial. When the same high rewards were offered continuously trial after trial, people were more inclined to simply stick with doing what had worked previously. We demonstrated such enhancements in flexibility in task switching, a difficult visual search task, and an easier priming of pop-out search task, which shows that this effect generalizes from executive tasks to perceptual processes that require relatively little executive control. These findings suggest that relative, transient changes in reward can exert more potent effects on behavioral flexibility than can the absolute amount of reward, whether it consists of money or points in a social competition.     

Experiences of being homeless or at risk of being homeless among Canadian youths

A qualitative study was undertaken with four groups--immigrants, youths, Aboriginal people, and landlords--in order to explore, compare, and contrast diversity issues among the homeless population and those at risk of homelessness in a larger Canadian city (Calgary, Alberta) with a smaller city (Lethbridge, Alberta), to better understand their and to needs make recommendations for improvement in service delivery and policy formation. This paper focuses on the findings from our sample of youths who shared information on a range of factors that contributed to their being homeless or at risk of being homeless. The youths in this study also shared their positive as well as negative experiences with educators, peers, family members, and social service providers. Canada's homeless include growing numbers of young people, families, women, and members of various ethnic communities, including Aboriginal people and immigrants. Today it is no longer possible to articulate a single silhouette of the homeless, but rather a diversity of profiles is needed. It was in the light of this reality that a study, "Diversity Among the Homeless and Those At Risk," was carried out. It was undertaken with four groups--immigrants, youths, Aboriginal people, and landlords.