Choice in a "self-control" paradigm: effects of a fading procedure

Pigeons chose between an immediate 2-second reinforcer (access to grain) and a 6-second reinforcer delayed 6 seconds. The four pigeons in the control group were exposed to this condition initially. The four experimental subjects first received a condition where both reinforcers were delayed 6 seconds. The small reinforcer delay was then gradually reduced to zero over more than 11,000 trials. Control subjects almost never chose the large delayed reinforcer. Experimental subjects chose the large delayed reinforcer significantly more often. Two experimental subjects showed preference for the large reinforcer even when the consequences for pecking the two keys were switched. The results indicate that fading procedures can lead to increased “self-control” in pigeons in a choice between a large delayed reinforcer and a small immediate reinforcer.     

The acquisition of taste aversions in humans

A written questionnaire or an interview was given to 517 undergraduates concerning their acquisition of illness-induced (taste) aversions to foods and drinks. The subjects reported 415 aversions, with 65% of the subjects reporting at least one aversion. The aversions were more likely to be reported as having been formed through forward rather than simultaneous or backward conditioning, and long-delay learning was frequent. The aversions usually formed to the taste of the foods, rather than the appearance or other aspects of the foods. Extinction appeared more effective in decreasing the aversions than did forgetting. The illness responsible for the aversion's forming was usually attributed to the subsequently aversive food, but for 21% of the reported aversions subjects were sure that something else had caused their illness. Aversions were more likely to have formed to relatively less familiar and less preferred foods. Aversions were also more likely to form between the ages of 13 and 20. Generalization of the aversions to similar foods occurred in 29% of the cases. Approximately one fourth of the aversions were to alcoholic beverages. Finally, instances of aversions forming without food or drink consumption and instances of observational learning were reported. The data were quite similar to laboratory taste aversion data collected using other species and can help in optimizing taste aversion treatments of eating and drinking disorders. Taste aversions among humans are frequent and strong.     

Using Force: Australian Newspaper Depictions of Contacts Between the Police and Persons Experiencing Mental Illness

The media creates and sustains knowledge about socially relevant issues such as crime, mental illness, and policing. Past research suggests that while the media portrayal of the police is undoubtedly complex, their portrayal of people experiencing mental illness remains mainly negative. The depiction of their encounters in the mass media is of considerable interest because of the influential role the media has on public opinion and debate; however, there is a lack of current research in this area. This study aimed to examine media items in the major newspapers across Australia between January 2006 and December 2007 (n = 77) to investigate their portrayal of this interface. The dominant themes encountered in the initial analysis depicted people experiencing mental illness as dangerous and a threat to the public, where the mental health system has failed to manage them adequately. Further analyses found that people experiencing mental illness were stigmatised in a third of the media items reviewed and were represented significantly more negatively in these encounters than the police. Implications of these findings and some suggestions regarding possible strategies that could improve socially responsible media reporting and public discourse on mental illness are proposed.     

The effect of variable delays on self-control

Five pigeons served as subjects in an experiment that examined the effects of variable as opposed to fixed delays on preference in a self-control paradigm (choice between larger, more delayed and smaller, less delayed reinforcers). Nonindependent concurrent variable-interval schedules were used to measure choice. When delays to the larger, more delayed reinforcers were variable as opposed to fixed, the subjects showed an increased preference for that alternative (the self-control alternative). A series of regressions revealed that the hyperbolic decay model and incentive theory provided poor fits to the data, but a modified version of the generalized matching law provided an adequate fit. Together, consistent with a general prediction made by discounting models, the data supported the conclusion that variable delays can increase self-control. However, specific discounting models were not able to explain the present data well.     

Self-Control and Impulsiveness in Preschool Children

The Psychological Record - Eleven girls and nine boys, aged 41–59 months, chose repeatedly, under controlled laboratory conditions, between one sticker available immediately and three...     

Signal detection and matching: analyzing choice on concurrent variable-interval schedules.

Pigeons' pecks on a red key and a green key were followed by access to grain according to pairs of concurrent independent variable-interval schedules in a combined signal detection/matching law paradigm. Pecks on the red key were reinforced by the richer variable-interval schedule if a short-duration tone had been presented; pecks on the green key were reinforced by the richer variable-interval schedule if a long-duration tone had been presented. Pecks on the green key given a short-duration tone, or on the red key given a long-duration tone, were reinforced by the leaner variable-interval schedule. The data were analyzed according to both signal detection's and the matching law's separate measures of, first, the discrimination of the choices and, second, the bias to make one response or another. Increasing the difficulty of the tone-duration discrimination decreased both methods' measures of the discrimination of the choices and did not change both methods' measures of the bias to make one response or another. Changing the leaner variable-interval schedule so that it approached the richer variable-interval schedule decreased signal detection's measure of discrimination but left its measure of response bias and the matching law measures unchanged. Data collected only until a subject's first changeover response following presentation of a long or a short tone showed higher values for both methods' measures of discrimination, no change in signal detection's measure of response bias, and lower values for the matching law's measure of response bias. Relationships between the matching law's and signal detection's methods of analyzing choice are discussed. It is concluded that a signal detection analysis is more efficient for examining changes in the difficulty of a discrimination, whereas a matching law analysis is more effective for examining the effects of changes in relative reinforcer frequency.     

Individual differences in magnitude estimation of loudness

Twenty-two male and female subjects, aged 15 to 31 years, participated in two sessions, 11 weeks apart, of magnitude estimations of loudness. Stable individual differences in the exponent of the psychophysical power law, ψ=k?ⁿ, were shown. The correlation between subjects’ exponents of the first and second sessions was +.59. The generality of these findings and the origin of the individual differences were discussed.     

Matching in concurrent variable-interval avoidance schedules

After pretraining with multiple variable-interval avoidance schedules, two rats were exposed to a series of concurrent variable-interval avoidance schedules. Responses on two levers cancelled delivery of electric shocks arranged according to two independent variable-interval schedules. The ratio of responses and time spent on the two levers approximately matched the ratio of shocks avoided on each. Matching to the number of shocks received was not obtained. Concurrent variable-interval avoidance can therefore be added to the group of positive and negative reinforcement schedules that can be expressed in the quantitative framework of the matching law.     

The relationship among the transtheoretical model of behavioral change,psychological distress,and diet attitudes in obesity: Implications for primary care intervention

Obesity is prevalent but undertreated in primary care. Family practice volunteer outpatients (N=454) were administered the Stage of Change for Weight (URICA), the Brief Symptom Inventory (BSI), and the Diet Readiness Test (DRT) to assess the relationship between these variables and obesity. The body mass index (BMI) was used to classify obesity revealing 197 patients with elevated BMI's. There was no significant difference between the obese and the nonobese on any of the psychological measures. The obese reported significantly more difficulty setting diet goals and less control over their eating, ate more to emotional situations, and exercised less than the nonobese. The obese sample (46.7%) reported being in the Action stage of change for weight management. Implications for intervention in primary care include targeting attitudes (DRT) and dispelling physician attitudes that obese individuals have increased levels of psychological distress. Addressing Stage of Change for weight management can facilitate tailoring the appropriate intervention when used in concert with the DRT variables.