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Measuring and modeling the interaction among reward size, delay to reward, and satiation level on motivation in monkeys.

ABSTRACT: Motivation is usually inferred from the likelihood or the intensity with which behavior is carried out. It is sensitive to external factors (e.g., the identity, amount, and timing of a rewarding outcome) and internal factors (e.g., hunger or thirst). We trained macaque monkeys to perform a nonchoice instrumental task (a sequential red-green color discrimination) while manipulating two external factors: reward size and delay-to-reward. We also inferred the state of one internal factor, level of satiation, by monitoring the accumulated reward. A visual cue indicated the forthcoming reward size and delay-to-reward in each trial. The fraction of trials completed correctly by the monkeys increased linearly with reward size and was hyperbolically discounted by delay-to-reward duration, relations that are similar to those found in free operant and choice tasks. The fraction of correct trials also decreased progressively as a function of the satiation level. Similar (albeit noiser) relations were obtained for reaction times. The combined effect of reward size, delay-to-reward, and satiation level on the proportion of correct trials is well described as a multiplication of the effects of the single factors when each factor is examined alone. These results provide a quantitative account of the interaction of external and internal factors on instrumental behavior, and allow us to extend the concept of subjective value of a rewarding outcome, usually confined to external factors, to account also for slow changes in the internal drive of the subject.

SUBMITTER: Minamimoto T

PROVIDER: S-EPMC2637024 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Measuring and modeling the interaction among reward size, delay to reward, and satiation level on motivation in monkeys.

Minamimoto Takafumi T La Camera Giancarlo G Richmond Barry J BJ

Journal of neurophysiology 20081105 1

Motivation is usually inferred from the likelihood or the intensity with which behavior is carried out. It is sensitive to external factors (e.g., the identity, amount, and timing of a rewarding outcome) and internal factors (e.g., hunger or thirst). We trained macaque monkeys to perform a nonchoice instrumental task (a sequential red-green color discrimination) while manipulating two external factors: reward size and delay-to-reward. We also inferred the state of one internal factor, level of s ...[more]

PMID: 18987119

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Project description:BackgroundThe threshold of 2.3 skilled health workers per 1,000 population, published in the World Health Report in 2006, has galvanized resources and efforts to attain high coverage of skilled birth attendance. With the inception of the Sustainable Development Goals (SDGs), a new threshold of 4.45 doctors, nurses, and midwives per 1,000 population has been identified. This SDG index threshold indicates the minimum density to respond to the needs of health workers to deliver a much broader range of health services, such as management of non-communicable diseases to meet the targets under Goal 3: Ensure healthy lives and promote well-being for all people of all ages. In the United Republic of Tanzania, the density of skilled health workers in 2012 was 0.5 per 1,000 population, which more than doubled from 0.2 per 1,000 in 2002. However, this showed that Tanzania still faced a critical shortage of skilled health workers. While training, deployment, and retention are important, motivation is also necessary for all health workers, particularly those who serve in rural areas. This study measured the motivation of health workers who were posted at government-run rural primary health facilities.ObjectivesWe sought to measure three aspects of motivation-Management, Performance, and Individual Aspects-among health workers deployed in rural primary level government health facilities. In addition, we also sought to identify the job-related attributes associated with each of these three aspects. Two regions in Tanzania were selected for our research. In each region, we further selected two districts in which we carried out our investigation. The two regions were Lindi, where we carried out our study in the Nachingwea District and the Ruangwa District, and Mbeya, within which the Mbarali and Rungwe Districts were selected for research. All four districts are considered rural.MethodsThis cross-sectional study was conducted by administering a two-part questionnaire in the Kiswahili language. The first part was administered by a researcher, and contained questions for gaining socio-demographic and occupational information. The second part was a self-administered questionnaire that contained 45 statements used to measure three aspects of motivation among health workers. For analyzing the data, we performed multivariate regression analysis in order to evaluate the simultaneous effects of factors on the outcomes of the motivation scores in the three areas of Management, Performance, and Individual Aspects.ResultsMotivation was associated with marital status (p = 0.009), having a job description (p<0.001), and number of years in the current profession (<1 year: p = 0.043, >7 years: p = 0.042) for Management Aspects; having a job description (p<0.001) for Performance Aspects; and salary scale (p = 0.029) for Individual Aspects.ConclusionHaving a clear job description motivates health workers. The existing Open Performance Review and Appraisal System, of which job descriptions are the foundation, needs to be institutionalized in order to effectively manage the health workforce in resource-limited settings.

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Dataset Information

Measuring and modeling the interaction among reward size, delay to reward, and satiation level on motivation in monkeys.

Publications

Measuring and modeling the interaction among reward size, delay to reward, and satiation level on motivation in monkeys.

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