Effects of prefeeding on the DRL preformance of rats with septal lesions.

Two experiments reported the effects of prefeeding normal and septal rats prior to their daily sessions on a differential reinforcement of low rates (DRL-20) schedule. Prefeeding reduced responses and increased reinforcements in the case of septal animals, regardless of the level of body weight. In the case of normal animals, prefeeding led to a decrease in responding and an increase in the number of reinforcements obtained only when the animals were at 85% of ad-lib levels, prefeeding, although it decreased responding, also decreased the frequency of obtained reinforcements. These results implied an impairment in normal animals in the discrimination of response feedback by stimulation arising from stomach distention.     

Behavioral momentum: the effects of the temporal separation of rates of reinforcement.

In Part 1 of the experiment, rats responded under a variable-interval (VI) 30-s schedule and a VI 120-s schedule, with each in effect for a block of consecutive sessions. That is, the two VI schedules were presented in successive conditions. In Part 2 the VI schedules alternated each day, and in Part 3 the schedules alternated within the session as a multiple schedule. For half of the rats in Parts 1 and 2, the VI schedule alternated every few minutes within the session with a stimulus that signaled extinction. For each part, once response rates had stabilized, resistance to change was measured by prefeeding and extinction. When the schedules were examined in successive conditions (Part 1), resistance to extinction was greater under the VI 120-s schedule of reinforcement than under the VI 30-s schedule, but no consistent differences in resistance to prefeeding were observed between the two VI schedules. When the VI schedules alternated each day (Part 2), resistance to extinction was greater under the VI 120-s schedule. However, no consistent differences in resistance to prefeeding were observed between the VI schedules without extinction in Group A, but resistance to prefeeding was greater under the VI 30-s schedule for rats with the added extinction component in Group B. When the VI schedules alternated within the session as a multiple schedule (Part 3), resistance to extinction and resistance to prefeeding were greater under the VI 30-s schedule. The data suggest that different rates of reinforcement, and their accompanying discriminative stimuli, must be compared within the same session (or at least on alternate days) to produce data consistent with the behavioral momentum model.     

Some conditions for the dissociation of consummatory and instrumental behavior in rats

To investigate whether consummatory and instrumental behavior depend upon different motivational factors, rats were trained to press a bar for saccharin solution, then given various treatments designed to reduce the palatability of saccharin, and finally tested for bar-pressing in extinction and for free intake of saccharin. Prefeeding with dextrose, prefeeding with saccharin, and association of saccharin with injections of lithium chloride all reduced intake of saccharin compared to control treatments, but only prefeeding with dextrose also reduced barpressing in extinction. Thus, performance of an instrumental response may depend upon need for food rather than appetite for it.     

Motivation in concurrent variable-interval schedules with food and water reinforcers

The lever pressing of four food- and water-deprived rats was reinforced on concurrent variable-interval schedules. Food reinforced one response, and water reinforced the other. Response rates in baseline were higher in the food component than in the water component. After response patterns and body weights had stabilized, the animals were given access to either food only, water only, both food and water, or neither food nor water (baseline) before daily sessions. Giving food before a session decreased per cent time in the food component, decreased overall response rates for food, and increased overall response rates for water. Giving water before a session increased per cent time in the food component, increased overall response rates for food, and decreased overall response rates for water. Giving both food and water before a session resulted in a combination of prefeeding and prewatering effects. More food and more water were consumed when both were available than when only one was available before a session.     

Response-dependent point loss and response force as disrupting operations on behavioral resistance to change in humans

Behavioral momentum theory (BMT) provides a theoretical and methodological framework for understanding how differentially maintained operant responding resists disruption. A common way to test operant resistance involves contingencies with suppressive effects, such as extinction or prefeeding. Other contingencies with known suppressive effects, such as response-cost procedures arranged as point-loss or increases in response force, remain untested as disruptive events within the BMT framework. In the present set of three experiments, responding of humans was maintained by point accumulation programmed according to a multiple variable-interval (VI) VI schedule with different reinforcement rates in either of two components. Subsequently, subtracting a point following each response (Experiment 1) or increasing the force required for the response to be registered (Experiments 2 and 3 decreased response rates, but responding was less disrupted in the component associated with the higher reinforcement rate. The point-loss contingency and increased response force similarly affected response rates by suppressing responding and human persistence, replicating previous findings with humans and nonhuman animals when other types of disruptive events (e.g., extinction and prefeeding) were investigated. The present findings moreover extend the generality of the effects of reinforcement rate on persistence, and thus BMT, extending the analysis of resistance to two well-known manipulations used to reduce responding in the experimental analysis of behavior.     

Satiation, capacity, and within-session responding

Responding may change substantially over the course of a session (McSweeney, Hinson, & Cannon, 1996). The role of satiation in this effect was investigated in three experiments. Experiment 1 showed that the capacity of pigeons to consume milo over a 1-hr period was relatively stable across three different methods of measurement. In Experiment 2, pigeons were divided into two groups that differed in their capacity based on one of those measures. Key pecking was then reinforced under a variable-interval 30-s schedule with hopper durations of 2 or 5 s. According to the satiation hypothesis, subjects with small capacities should satiate faster and therefore show greater decreases in food-reinforced responding than would subjects with larger capacities. The results confirmed this prediction and showed that the magnitudes of within-session decreases were better predicted by the amount an animal consumed relative to its capacity than by absolute amount alone. In Experiment 3, each pigeon was prefed 0, 5, 15, or 25 g of milo prior to each session. Consistent with the satiation hypothesis, increases in prefeeding produced lower overall response rates in the smaller capacity subjects than in the larger capacity subjects at each level of prefeeding. These experiments demonstrate the importance of a new variable in the control of behavior, and provide a recommended technique for its measurement.     

The influence of food distribution on the aggressive behaviour of juvenile white-seabream (Diplodus sargus cadenati de la Paz,Bauchot and Daget, 1974)

Experiments were conducted to investigate the effect of differences in the spatial distribution of food on the aggressive behaviour of juvenile white-seabream, Diplodus sargus cadenati, both in the presence and in the absence of food. The groups of fish receiving spatially fixed food displayed less aggression than those receiving spatially variable food. The period (before, during, or after feeding) during which aggressiveness is measured also has influence in the results. During the prefeeding and postfeeding periods (absence of food), groups that were fed with food spatially fixed displayed less aggression than those that received spatially variable food. However, when food was present there were no differences in the number of aggressive acts carried out by fish groups in both environments. The aggressiveness shown by the groups of fish was always more pronounced during the postfeeding period than during the prefeeding period. The dominant fish was more aggressive when food was spatially fixed, and especially when food was present. Therefore, the subordinates were more aggressive when food was spatially variable and particularly when food was present and during the postfeeding period. Aggr. Behav. 24:379–384, 1998. © 1998 Wiley-Liss, Inc.     

Does the context of reinforcement affect resistance to change?

Eight pigeons were trained on multiple schedules of reinforcement where pairs of components alternated in blocks on different keys to define 2 local contexts. On 1 key, components arranged 160 and 40 reinforcers/hr; on the other, components arranged 40 and 10 reinforcers/hr. Response rates in the 40/hr component were higher in the latter pair. Within pairs, resistance to prefeeding and resistance to extinction were generally greater in the richer component. The two 40/hr components did not differ in resistance to prefeeding, but the 40/hr component that alternated with 10/hr was more resistant to extinction. This discrepancy was interpreted by an algebraic model relating response strength to component reinforcer rate, including generalization decrement. According to this model, strength is independent of context, consistent with research on schedule preference.     

Effects of gastric loading on the sucking response and voluntary milk intake in neonatal piglets.

The effects of loading the stomach of piglets with 100 ml of milk after 6 hr of fasting and immediately before allowing them access to the dam were studied. Piglets gained less weight and rested more often on preloaded days. This suggests that gastric receptors exist and signal distension of the stomach. Monitoring sucking responses to a rubber teat revealed that although preloading the stomach substantially reduced voluntary milk intake during the initial 10-min. period of the test, the vigorous oral activity continued largely unabated. Isotonic saline suppressed the voluntary milk intake of the piglets for a shorter period than milk or isotonic glucose solution.     

Accuracy of discrimination,rate of responding,and resistance to change

Pigeons were trained on multiple schedules in which responding on a center key produced matching-to-sample trials according to the same variable-interval 30-s schedules in both components. Matching trials consisted of a vertical or tilted line sample on the center key followed by vertical and tilted comparisons on the side keys. Correct responses to comparison stimuli were reinforced with probability .80 in the rich component and .20 in the lean component. Baseline response rates and matching accuracies generally were higher in the rich component, consistent with previous research. When performance was disrupted by prefeeding, response-independent food during intercomponent intervals, intrusion of a delay between sample and comparison stimuli, or extinction, both response rates and matching accuracies generally decreased. Proportions of baseline response rate were greater in the rich component for all disrupters except delay, which had relatively small and inconsistent effects on response rate. By contrast, delay had large and consistent effects on matching accuracy, and proportions of baseline matching accuracy were greater in the rich component for all four disrupters. The dissociation of response rate and accuracy with delay reflects the localized impact of delay on matching performance. The similarity of the data for response rate and accuracy with prefeeding, response-independent food, and extinction shows that matching performance, like response rate, is more resistant to change in a rich than in a lean component. This result extends resistance to change analyses from the frequency of response emission to the degree of stimulus control, and suggests that the strength of discriminating, like the strength of responding, is positively related to rate of reinforcement.     

Psychosocial correlates of frequent indoor tanning among adolescent boys

The aim of the current study was to assess psychosocial correlates (i.e., perceived weight, weight control strategies, substance use, and victimization) of frequent indoor tanning in adolescent boys—a group at high risk for developing skin cancer. Participants (N = 7,907) were drawn from a nationally representative sample of adolescent boys attending high school in the United States. Binary logistic regression revealed that extreme weight control strategies, particularly steroid use (odds ratio = 3.67) and compensatory vomiting (odds ratio = 2.34), along with substance use and victimization, were significantly related to frequent indoor tanning. These results highlight the role of appearance-changing, and health-risk behaviors in the context of frequent indoor tanning. Skin cancer prevention interventions may benefit from adopting approaches that integrate the treatment of body dissatisfaction and subsequent maladaptive behaviors.     

Key-peck probability and topography in a concurrent variable-interval variable-interval schedule with food and water reinforcers.

The relation between variables that modulate the probability and the topography of key pecks was examined using a concurrent variable-interval variable-interval schedule with food and water reinforcers. Measures of response probability (response rates, time allocation) and topography (peck duration, gape amplitude) were obtained in 5 water- and food-deprived pigeons. Key color signaled reinforcer type. During baseline, response rates and time allocations were greater to the food key than to the water key, and food-key pecks had larger gapes and shorter durations. Relative probability measures (for the food key) were increased by prewatering and decreased by prefeeding. Deprivation effects upon topography measures were apparent only when food- and water-key pecks were analyzed separately. Food-key gape amplitudes increased with prewatering and decreased with prefeeding. The clearest effect occurred with prewatering. There were no consistent effects upon water-key gapes. The key color-reinforcer relation was reversed for 3 pigeons to determine how response topography was modulated during the transition from food- to water-key pecks. Reacquisition was faster for the probability than for the topography measures. Analysis of gape-amplitude distributions during reversal indicated that response-form modulation proceeded through the generation of intermediate gape sizes.     

THE ACQUISITION OF CONSERVATION OF SUBSTANCE AND WEIGHT IN CHILDREN

S medslund , J. The acquisition of conservation of substance and weight in children. I. Introduction. Scand. J. Psychol ., 1961, 2 , 11–20.—This is the first in a series of articles concerning the problem of how children acquire the concepts of conservation of substance and weight. The four alternative interpretations of nativism, maturation theory, learning theory and equilibration theory are discussed. It is concluded that nativism and maturation theory do not account for the known facts. An important issue is whether the concepts are established by external reinforcement (learning theory) or by a process of inner equilibration, as maintained by Piaget.     

Domestic violence shelter residents' substance abuse treatment needs and options

The association between intimate partner aggression and alcohol and other substance use problems is well-established in the literature. However, the nature and scope of alcohol and other substance use problems in women who seek or are likely to seek domestic violence shelter services is difficult to ascertain. The first goal of the current review was to identify and synthesize the findings of studies in which alcohol and other substance use, problem use, or diagnoses in shelter residents was assessed. Despite methodological limitations, this body of studies provides compelling evidence that a substantial number of domestic violence shelter residents (22–72%) have current or past problems with alcohol or other substances and may benefit from treatment. The second goal of the current review was to provide an overview of the availability and limitations of options that are currently available to address domestic violence shelter residents' substance abuse treatment needs. Although substance abuse is a largely under-met need of women seeking domestic violence shelter, promising findings from model integrated treatment programs, as well as the knowledge gained through implementation of these programs provide useful future directions for addressing these co-occurring issues.     

Effects of obesity and set point on taste responsiveness and ingestion in humans.

Two experiments investigated the relationships among degree of obesity, nearness to set point for adipose tissue mass, and responsiveness to taste. In Experiment 1, subjects rated milkshakes varying in sweetness intensity. Overweight and normal weight subjects did not have significantly different detection thresholds or preference ratings. However, overweight subjects worked longer than normals to obtain their most preferred substance. Experiment 2 varied the ease of tasting the milkshake. Preference and food intake of moderately overweight subjects were significantly more influenced by tastes that they found positive and negative than was the preference of normal weight or obese subjects. The ease of ingesting the taste substance also significantly influenced preference and food intake of the moderately obese only. Nearness to set point, operationally defined as weight stability for 2 years, had no significant effects.     

Rats defend different body weights depending on palatability and accessibility of their food.

Normal adult rats lived on powdered diets adulterated to contain as much as 1.6% quinine sulfate, on a palatable high-fat diet, or in Skinner boxes with 45-mg Noyes pellets available on fixed-ratio (FR) schedules as high as FR 156. They maintained lower body weights over periods of months in proportion to the percentage of quinine adulteration or the fixed ratio. Rats exposed to the high-fat diet overate as much and gained weight as rapidly as rats recovering from food deprivation, and became moderately obese. Rats having become lean or obese contingent on the palatability or accessibility of their diet defended body weight by eating more in the cold, less when force-fed by gavage, and more to restore weight after food deprivation. Yet on chow they restored and defended body weights typical of rats whose diet had been confined to commercially prepared chow. These results are interpreted to be inconsistent with motivational models that rigidly distinguish drive from incentive, that treat body weight changes as evidence for failure to regulate energy balance or body weight, or that rely exclusively on deprivation of food or reduction of body weight for definitions of need for calories. Instead, caloric homeostasis in rats may incorporate ecological constraints.     

The punishment of persistent vomiting: a case study

In an attempt to control severe vomiting in a mentally retarded patient, shock was delivered after each stomach tension, a pre-vomiting response that consisted of an overt abdominal movement. Contingent shock resulted in an initial transitory increase followed by a decrease in rate of stomach tensions. There was a decrease in emitted vomitus, which resulted in a weight gain of the patient.     

Body image and body change strategies among adolescent males and females from Fiji, Tonga and Australia

The current study was designed to investigate the body image and body change strategies of adolescents from Fiji, Tonga and Australia. Participants were 628 Fijians, 463 Indo-Fijians, 598 Tongans and 535 European Australians. Adolescents completed measures of height, weight, body dissatisfaction, strategies to lose weight, increase weight and increase muscles. The results demonstrated that overweight adolescents were more dissatisfied with their bodies than those who were normal weight. Overweight Fijians and Tongans were more satisfied with their body than Indo-Fijian or Australian adolescents. Tongans, followed by Fijians and Indo-Fijians, were more likely to engage in strategies to lose weight, increase weight and increase muscles. These results are consistent with the focus in Fiji and Tonga on the value of the large body ideal, but may also reflect the recent focus on the attainment of a healthy body size.     

Differences between golden hamsters (Mesocricetus auratus) and Norway rats (Rattus norvegicus) in preference for the sole diet that they are eating

D. DiBattista (2002) reported that hamsters but not rats showed reduced preferences for the sole diet they had eaten for 10 days. In the current study, the authors fed Norway rats (Rattus norvegicus) a nutritious diet for either 3 or 10 days, then tested them either immediately or 1 or 3 days later. The authors found that like golden hamsters (Mesocricetus auratus), rats exhibited reduced preferences for a prefed diet but only if tested either immediately or 1 day after prefeeding, not if tested 3 days later (when D. DiBattista tested his hamsters). Rats and hamsters differed in the longevity, not the development, of reduced preferences for a palatable food eaten for several consecutive days. Such a response might aid dietary generalists in constructing balanced diets when no single available food is nutritionally adequate.     

Mind and space: a Confucian perspective

This essay explores the Confucian concept of the space of the mind and the Confucian view on cultivation of the space of mind. It then argues that the distinction between the mind as a mental substance and the body as a material substance is that the mind can be infinitely extended while the body can only extended to a certain limit.