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To identify biobehavioral mechanisms underlying excessive reward consumption, reward valuation-effort (RV-E) assessments should (a) parallel measures in basic science to permit translation from preclinical to clinical studies; (b) quantify constructs dimensionally from healthy to disease states; and (c) hold relevance across different diagnostic categories. To address these aims, we developed a progressive ratio (PR) task whereby RV-E is measured as breakpoint when participants worked for access to playing a game. We evaluated test-retest reliability of breakpoint and convergent and discriminant validity of interpretations of this score against an established PR task for food. In Study 1, female undergraduates (N = 71; 33% racial minority; 28% ethnic minority) completed the game and food tasks in fasted and fed states. In Study 2, women (N = 189; 29% racial minority; 27% ethnic minority) with eating disorders (n = 158) were compared to controls (n = 31) on tasks. Game task breakpoint demonstrated excellent test-retest reliability, intraclass correlation coefficient (ICC) = .91, 95% CI [.80, -.96], over 2 weeks and convergent validity with the fasted food task (r = .51, p < .001). Consistent with animal models, breakpoint was lower in fed compared to fasted states across tasks, B (SE) = 321.01 (552.40), p < .001. Finally, the game task demonstrated discriminant validity from measurement of satiation. In Study 2, women with eating disorders demonstrated higher breakpoint on both tasks compared to controls, and game PR task breakpoint decreased from a fasted to fed state. The game PR task offers a novel approach for translating results from animal models of RV-E into testable hypotheses in nonclinical and clinical samples. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Humans (as well as animals) have an inherent tendency to seek out rewards and to avoid punishments. This tendency is crucially important in daily life. The brain selects those behavioral actions that have high probabilities of leading to highly valuable outcomes. Therefore, the brain should compute the value as well as the probability of future rewards in order to make optimal decisions. One of the main questions of this thesis was: how does the human brain assess the value and probability of potential future rewards? Other questions that I addressed in this thesis are: How can the subjective value of monetary rewards be assessed? Are there individual differences in reward sensitivity as reflected in learning style? And as reflected in spontaneous fluctuations in brain activity? In Chapter 2 the startle reflex was used as a readout measure of motivational state during the anticipation, obtainment and omission of rewards with varying magnitudes in order to compare the value of these rewards. However, no evidence was found for systematic increases in startle modulation with increased reward magnitude at stake. The aim of Chapter 3 and 4 was to investigate whether there are individual differences in reward sensitivity as reflected in the extent to which subjects learn from reward and punishment feedback as assessed by the probabilistic selection task (PST) and as reflected in the ratio between spontaneous slow-wave theta and fast-wave beta oscillations in the electro-encephalogram. The results indicate that neither of these two methods could be used as a reliable index of individual differences in reward sensitivity. The results of Chapter 3 show that categorization as being reward/punishment sensitive may not solely reflect motivational style, but also the perceptual discriminability or salience of stimulus characters in the PST. The results of Chapter 4 show that high theta/beta EEG ratio is not related to high reward sensitivity, but rather to poor behavioral adapta

Learning can be instrumental in acquiring new skills or optimizing behaviour, but it is also costly in terms of energy and when maladaptive associations are formed: the balance between costs and benefits affects memory dynamics. Numerous studies have demonstrated that memory dynamics of animal species depend on the value of the reward during conditioning, even when animals are inexperienced with this reward. How an animal perceives reward value depends on a number of aspects, including the quantity or quality of the reward in terms of energy or fitness for the animal, the internal state of the animal and previous experience. The reliability of the learned association is another aspect, which can be assessed through the frequency of experiences, or through perception of inherent properties of the reward. The reward in oviposition learning of parasitic wasps is a host to parasitize. Different host species can differ in their reward value. This study focused on a specific aspect of reward value, namely host value, i.e. the number and size of emerging offspring, and tested the effect on oviposition learning in parasitic wasps of the genus Nasonia. We conditioned parasitic wasps of the species Nasonia vitripennis and Nasonia giraulti using three different host species as a reward, which differed greatly in their value as a host. However, for both parasitic wasp species, the resulting memory formation was independent of the value of the host. We discuss factors that may be responsible for this observation. (C) 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Learning can be instrumental in acquiring new skills or optimizing behaviour, but it is also costly in terms of energy and when maladaptive associations are formed: the balance between costs and benefits affects memory dynamics. Numerous studies have demonstrated that memory dynamics of animal species depend on the value of the reward during conditioning, even when animals are inexperienced with this reward. How an animal perceives reward value depends on a number of aspects, including the quantity or quality of the reward in terms of energy or fitness for the animal, the internal state of the animal and previous experience. The reliability of the learned association is another aspect, which can be assessed through the frequency of experiences, or through perception of inherent properties of the reward. The reward in oviposition learning of parasitic wasps is a host to parasitize. Different host species can differ in their reward value. This study focused on a specific aspect of reward value, namely host value, i.e. the number and size of emerging offspring, and tested the effect on oviposition learning in parasitic wasps of the genus Nasonia. We conditioned parasitic wasps of the species Nasonia vitripennis and Nasonia giraulti using three different host species as a reward, which differed greatly in their value as a host. However, for both parasitic wasp species, the resulting memory formation was independent of the value of the host. We discuss factors that may be responsible for this observation. (C) 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.