Voluntary Selection Research Articles

Voluntary herbage intake and diet selection in Scottish-Blackface ewes suckling twin lambs and grazing perennial ryegrass/white clover swards with or without protein supplementation

Mixed perennial ryegrass and white clover swards are often used as the basis of upland sheep grazing systems. This study’s objective was to examine voluntary herbage intake and diet selection in 30 lactating Scottish-Blackface ewes grazing mixed perennial ryegrass (PRG) and white clover (WC) swards supplemented with or without protein. The work was part of a wider study of nutrition and parasitology in organic sheep systems.

Body temperature regulation in the amphisbaenian Trogonophis wiegmanni

We studied the thermal ecology of the amphisbaenian Trogonophis wiegmanni at the Chafarinas Islands (North Africa). We aimed to evaluate the extent of thermoregulation in this fossorial amphisbaenian by analyzing the relationships between environmental available operative (Te) and body (Tb) temperatures of active individuals found under stones. Amphisbaenians are typical thigmotherms that obtain heat through contact with soil and, thus, Tb was closely correlated to Te under stones. However, the comparison of Tb with Tes available in the study area indicated that Tb deviated less from the set-point range of preferred temperatures than would result from a random response, which is indicative of behavioral temperature regulation. Measurements of Te under rocks selected by T. wiegmanni deviated significantly less from the range of preferred temperatures than Te beneath available rocks. This suggests that amphisbaenians occupied rocks with or when thermal properties were suitable for maintaining their preferred Tb. We found a bimodal pattern of Tb during the day, with amphisbaenians being active at higher Tb during the afternoon than in the morning. This did not reflect changes in the thermal environment, but was presumably a voluntary selection pattern, as indicated by similar results obtained in thermal gradients in a previous study. Also, juveniles had higher Tb than adults, but this might be a biophysical effect of differences in body size and heating rates. We conclude that amphisbaenians seem capable of regulating body temperature to an extent that comparable with epigeal diurnal lizards.

Effect of naltrexone on acute tolerance to ethanol in UChB rats

The effect of naltrexone (a non-selective opioid receptor antagonist) on both alcohol consumption in a voluntary selection situation and acute tolerance to the motor impairment effect of ethanol was examined in female high alcohol-drinking (UChB) rats using the tilting plane test. In experiment 1, the effect of naltrexone on alcohol consumption was studied in UChB rats which were given a daily 1-h period access to a 10% (v/v) ethanol solution with food and water always available. Naltrexone in doses of 5 or 10 mg/kg intaperitoneal (i.p.) caused dose-dependent reduction in voluntary alcohol intake by 45% and 66%, respectively, without altering daily water intake. In experiment 2, the effect of naltrexone (5 mg/kg i.p.) on acute tolerance to motor impairment effect of a dose of 2.3 g ethanol/kg i.p. was examined. A comparison of control (C) and naltrexone (Nal) UChB groups indicated that naltrexone slowed the recovery of the motor activity and reduce acute tolerance development at comparable ethanol levels in cerebral blood. These results suggest a contribution of the opioid system to acute tolerance to ethanol.

The influence of molar occlusal surface area on the voluntary intake, digestion, chewing behaviour and diet selection of red deer (Cervus elaphus)

The influence of molar occlusal surface area on the voluntary intake, digestion, chewing behaviour and diet selection of red deer (Cervus elaphus)

Limitations of palatability as a concept in food intake and diet selection studies

The concept of palatability occurs frequently in studies of voluntary food intake and diet selection (see for example the numerous references in Forbes, 1986). The purpose of this paper is to suggest that the concept is of limited value. Four major areas are considered. The first is that of definition, as the term is often used in an ambiguous manner. Secondly, the use of palatability as a food descriptor is challenged since it is essentially an animal rather than a food characteristic. Thirdly, the usefulness of the concept is challenged in the context of its evolutionary and ecological significance. Finally, it is contended that the response of the animal is not necessarily a good measure either of the stimulus received or of the resulting internal state.

Voluntary food intake and diet selection in farm animals

Voluntary food intake and diet selection in farm animals

Rehearsal strategies, test expectancy, and memory monitoring in free recall.

Three experiments were carried out to determine (a) the effectiveness of associative rehearsal and rote repetition for long-term recall with and without expectation of a later recall test, and (b) the subjects' ability to assess their own future recall performance. The overall results showed that a test expectancy effect was not obtained when a voluntary selection in strategies was prohibited, but was found for subjects not instructed in the use of any particular strategy. It is also shown that the subjects could predict correctly that the items studied with associative rehearsal would be recalled more successfully at the final test than when they were studied with rote repetition. A superiority of associative rehearsal for prediction was not found when the subjects used only one type of rehearsal, but was found when they were not given the immediate test. The results suggest that the expectancy effect can be explained in terms of subjects' intentional shifts of strategies based on their metacognitive assessment of such strategies.

Auto-assignment and enrollment in Medicaid managed care programs.

In the face of escalating Medicaid costs and anticipated reductions in federal Medicaid spending, states are increasingly converting from fee-for-service (FFS) to managed health care systems. The interrelated issues of enrollment and auto-assignment are fundamental to the overall success or failure of Medicaid managed care programs. The purpose of this article is to suggest how policy makers, consumer advocates, and providers should address these issues. My major premise is that implementation of managed care will proceed more smoothly if states adopt enrollment strategies that promote voluntary selection of health plans by Medicaid consumers, minimize the likelihood of auto-assignment, and mitigate the negative consequences of mandatory assignment of consumers to managed care organizations (MCOs).States seeking to implement Medicaid managed care must apply for a waiver from the secretary of the Department of Health and Human Services (DHHS). Two different types of waivers are available to implement Medicaid managed care.

Saccadic localization of eccentric forms

Saccades made to outline drawings of eccentric forms were compared with saccades made to single-point targets. Saccades could be directed to designated locations within eccentric forms nearly as accurately and precisely as they could be directed to single points. Saccades directed to the form as a whole landed at consistent locations near the center of the form. These results show that contour information is sufficient for accurate computation of a saccadic command and that this computation is constrained by the internal coding of the shape. A serial two-stage process, voluntary selection followed by a weighted-averaging process, is proposed for computation of the saccadic command based on information provided by shape.

Voluntary response selection in free association

Reaction time (RT) in free association (FA) is assumed to consist of three components: stimulus word encoding, response selection, and response generation. The RT of word naming contains the first and third components only. If response selection is a serial voluntary search it can be manipulated by rewarding response speeding. This would lead the subject to terminate the search sooner. Thus, greater speeding will be achieved for delayed responses, for which search was long, than for undelayed ones. This differential speeding effect was observed in Experriment 1 (N=17), in which the task was FA. Speeding effect was not differential in Experiment 2, in which the subjects (N=16) were given a word naming task. Both of these experiments employed a between‐subjects design. Their results were replicated in Experiment 3 (N=13), which employed a within‐subject design. The results, taken together, suggest that differential speeding is specific to response selection, in accordance with Flekkoy's (1973a, 1981) voluntary selection model. However, they are inconsistent with the traditional associonistic models.

Voluntary selection of the target for smooth eye movement in the presence of superimposed, full-field stationary and moving stimuli

Prior work has shown that smooth eye movements in the presence of both stationary and moving stimuli are determined, at least in part, by the voluntary selection of either the stationary or the moving stimulus as the target for smooth eye movements. The effectiveness of voluntary selection in eliminating the influence of the stimuli not selected (i.e. backgrounds) on smooth eye movement is not known because prior studies used targets and backgrounds with different physical characteristics. Thus, effects of voluntary selection were confounded with the relative strength of target and background as stimuli for smooth eye movements. We measured eye movements (resolution 1′) of two highly-experienced eye movement subjects with a target and background with the same physical characteristics: two, identical, full-field, superimposed patterns of randomly-positioned dots (1 dot/deg 2 or 8 dots/deg 2). One field was stationary and the other moved at 70.2 minarc/sec. The effect of the moving background on smooth eye movements when the stationary field was the target and the effect of the stationary background on smooth eye movements when the moving field was the target was negligible (0–4% for one subject; 0–2% for the other). The influence of the background on smooth eye movements was affected by a six-fold reduction in the intensity of either the target or background, but effects of such intensity changes were small and different for each subject. Taken together, these results show that the effectiveness of voluntary selection in eliminating the influence of background stimuli on smooth eye movements can be virtually complete. Any observed influence of the background—however small—can be attributed to voluntary factors (e.g. subjects' failure to apply sufficient effort or attention) rather than to the operation of an involuntary mechanism that automatically integrates velocity information from target and background. The attention and effort required to ensure that voluntary selection is perfect may impair the accuracy of psychophysical judgments made about the background.

Affective state and the selective exposure to and use of television

Zillmann's “annoyance reduction” hypotheses were used to test the relationship between affective states and voluntary television selection and use. The results indicated that annoyed individuals viewed television significantly less than praised individuals.

Effect of chronic vasopressin treatment on alcohol drinking of Brattleboro HZ and DI rats

Preference for alcohol was determined for three groups of male and female rats, 100–150 days old, comprised of: (1) Long Evans (LE); (2) LE-derived Brattleboro heterozygous (HZ); and (3) Brattleboro homozygous (DI) animals afflicted with diabetes insipidus due to vasopressin deficiency. Each alcohol drinking test was run over 11 days during which food, water and an ethyl alcohol solution, increased in concentration from 3% to 25%, were freely available. Following an initial preference screen, 100 milli-units of vasopressin tannate in oil was administered subcutaneously, during a second preference test, once per day to each animal. This treatment ameliorated the polydipsia-polyuria syndrome characteristic of the DI sub-strain of Brattleboro rat. Administration of the peptide to both the LE or HZ animals exerted no effect on g/kg intake nor on the proportional measure of alcohol to water. However, in the DI rat of either gender, vasopressin reduced the mean absolute gram intake of alcohol over concentrations to resemble that of the other LE and/or HZ groups. These results demonstrate that vasopressin serves to normalize the intake of alcohol in the DI rat by virtue of the elimination of the diabetic condition. However, since vasopressin fails to alter alcohol consumption of the HZ and LE rats, it would appear that this neuroactive peptide may play only a minor role in the CNS mechanisms governing the voluntary selection of alcohol.

“Subject” and “Structure” in Power-phenomena

Among the conventional theories of power structure, the predominant notion is that power-phenomena contain no longer the centralized unitary structure but the pural one which comprises polymorphous games of strategies adapting to each condition. But one of the recent trends in power-analyses tries to make clear the deep structure which underlies and determines the various phenomena of power-relations. In this type of analysis, however, some difficult problem will befall us. It is how to relate “subjectivity” to “structure”.S. Lukes presumes power exercise as realization of “subjectivity” to the extent that he considers the room of discretion within structurally determined limits. S. Clegg, on the contrary, refuses the existence of “subjectivity” by regarding that the criterion of seemingly voluntary selection is determined by “form of life” which is beyond each individual and socially monolithic. It is M. Foucault's power-analysis that provides with one bridge to link these two opposite views. He implies the most fundamental principle of knowledge by the term “pouvoir pastorat” and then does not accept “subjectivity”. But at the same time, he takes a view of some resistances rejecting the “Pouvoir” itself. Such conflict situations indicate the plurality of the principle of knowledge.This would mean that “subjectivity” exists not within the “structural” limits but in the relation of the conflicts about “structure” mentioned above.

Alcohol intake, ethanol-induced narcosis and intoxication in rats following neonatal 6-hydroxydopamine or 5,7-dihydroxytryptamine treatment

Newborn rats were treated with 5,7-dihydroxytryptamine (5,7-HT; 2 x 100 mg/kg s.c., 24 h interval) after pretreatment with desipramine (20 mg/kg s.c.) for depletion of brain 5-hydroxytryptamine (5-HT) or with 6-hydroxydopamine (6-OHDA; 3 x 100 mg/kg s.c., 24 h interval) for selective reduction of brain noradrenaline (NA). The 5,7-HT treatment resulted in a 53% reduction in endogenous 5-HT in the cerebral cortex and a 60% increase in the pons-medulla when determined in adult rats. The 5-HT content in the midbrain was not affected. Endogenous NA in the 6-OHDA treated animals was selectively reduced by 100% in the cerebral cortex, 35% in the midbrain and increased by 117% in the pons-medulla. No difference was found between the voluntary ethanol selection of these groups and that of the controls when measured at the age of 3 months. In a tilting-plane test, ethanol (2 g/kg i.p.) impaired the performance of the 6-OHDA treated rats significantly more than that of the controls. Moreover ethanol (4 g/kg e.p.) produced significantly longer narcosis in these rats. In contrast, the 5,7-HT treated rats were not affected significantly more than the controls in these tests. These results suggest that catecholamine neuronal systems interact with the expression of alcohol intoxication.

Tetrahydroisoquinolines in the Brain: The Basis of an Animal Model of Alcoholism

Quite surprisingly, the direct introduction of THP into the brain induces a remarkable shift in voluntary alcohol intake... Even as much as 6 mo later, with no further infusions of THP, the remarkable voluntary selection of alcohol did not abate.

Randomized invitations: One solution to the problem of voluntary treatment selection in program evaluation research

An alternative to randomized assignment to treatments in social program evaluation research is proposed in the form of randomized invitation to treatment. A procedure is suggested for identifying a subset of the uninvited control group that is maximally equivalent to those in the invited group who self-select into treatment in order to increase power to detect treatment effects on outcome measures.

Brain sensitivity to alcohol in inbred mouse strains.

The voluntary selection of aqueous ethanol in preference to water has been studied in a number of animal species. A pharmacological phenomenon observed in all species, including humans, is depression of the central nervous system which eventually leads to "sleep." The sleeping time at a given concentration of alcohol in the brain depends on strain sensitivity.

Doctor-patient relationship.

Because everything the physician does to or for his patient has a psychological effect on the patient the doctor-patient relationship is his most powerful tool. Three aspects of this relationship are discussed: 1) the voluntary selection of physician by the patient 2) continuity of treatment by the same physician 3) the third party payment of fees for doctor's services. These three considerations may influence the patient's or the doctor's attitude toward the other. A questionnaire was addressed to the 89 members of the staff of the Institute of the Pennsylvania Hospital which includes four heads of departments of psychiatry, two heads of departments of neurology, members of the departments of psychiatry in all five local medical schools, two past presidents of the APA etc. The psychiatric experiences of the 82 who replied ranged from three to 52 years. Three groups were identifiable on the basis of their formal relationship with psychoanalysis. “A” group (26) had no such formal connection; “B” group (30) included 18 members of the American Psychoanalytic Association and eight graduates of psychoanalytic institutes; and “C” group (30) were students of a psychoanalytic institute. Sixty-six of the respondents were certified in psychiatry by either the American Board of Psychiatry and Neurology or its Canadian equivalent. The Tables show the “guestimated” replies to the question “How important do you feel the patient's voluntary selection of a psychiatrist is to the outcome of his treatment in comparison to the assignment of a psychiatrist of comparable training and experience. It would appear that the respondents felt that voluntary selection was most important for the neurotic, slightly less important for the patient with a character disorder and still less so for the schizophrenic and even less again for the patients suffering from an affective disorder. Other questions asked were: “How important to the outcome of treatment do you feel the uninterrupted continuity of doctor-patient relationship is”? This continuity of treatment by one physician was thought to be most important to all patients with the possible exception of those with affective disorders. Another question was; “In what percentage of their cases was a third party involved in payment”? What percentage of these patients benefitted by this and in what way those not benefitted were hindered? An average of 24% of patients enjoyed some form of third party payment, and 38% of these benefitted from this, mostly because without some financial assistance many patients could not get treatment, and it helps the psychiatrist to give better and more thorough treatment. For the percentage who were hindered by third party payment a number of reasons were given. It would, therefore, appear that the method of payment of physician's fees is at least as important to doctor-patient relationship as the voluntary selection of his physician by the patient.

VOLUNTARY INTAKE OF CALCIUM AND PHOSPHORUS IN PARTIALLY NEPHRECTOMIZED AND PARATHYROIDECTOMIZED RATS

THE RECENT EXPERIMENTS of Richter and Eckert (1, 2) indicate that the metabolism of calcium and phosphorus may be regulated in part by voluntary selection of these materials from the diet. In parathyroidectomized rats an increased amount of calcium and a decreased amount of phosphorus was consumed. This compensatory mechanism was sufficient to prevent or arrest manifestations of tetany. Further, this altered voluntary intake could be reversed by subsequent transplantation of parathyroid tissue. From these results it would seem reasonable to expect that in other conditions in which calciumand phosphorus metabolism is disturbed, alterations in their voluntary intake might be demonstrable. One such condition is chronic renal insufficiency. The evidence that such a disturbance may occur in this condition is as follows. (a)In renal insufficiency phosphorus excretion through the kidney is decreased, while its excretion in the intestine in the form of calcium phosphate is increased (3).