Reward Training Research Articles

Reward processing in the value-driven attention network: reward signals tracking cue identity and location.

Through associative reward learning, arbitrary cues acquire the ability to automatically capture visual attention. Previous studies have examined the neural correlates of value-driven attentional orienting, revealing elevated activity within a network of brain regions encompassing the visual corticostriatal loop [caudate tail, lateral occipital complex (LOC) and early visual cortex] and intraparietal sulcus (IPS). Such attentional priority signals raise a broader question concerning how visual signals are combined with reward signals during learning to create a representation that is sensitive to the confluence of the two. This study examines reward signals during the cued reward training phase commonly used to generate value-driven attentional biases. High, compared with low, reward feedback preferentially activated the value-driven attention network, in addition to regions typically implicated in reward processing. Further examination of these reward signals within the visual system revealed information about the identity of the preceding cue in the caudate tail and LOC, and information about the location of the preceding cue in IPS, while early visual cortex represented both location and identity. The results reveal teaching signals within the value-driven attention network during associative reward learning, and further suggest functional specialization within different regions of this network during the acquisition of an integrated representation of stimulus value.

Object-finding skill created by repeated reward experience.

For most animals, survival depends on rapid detection of rewarding objects, but search for an object surrounded by many others is known to be difficult and time consuming. However, there is neuronal evidence for robust and rapid differentiation of objects based on their reward history in primates (Hikosaka, Kim, Yasuda, & Yamamoto, 2014). We hypothesized that such robust coding should support efficient search for high-value objects, similar to a pop-out mechanism. To test this hypothesis, we let subjects (n = 4, macaque monkeys) view a large number of complex objects with consistently biased rewards with variable training durations (1, 5, or 30 + days). Following training, subjects searched for a high-value object (Good) among a variable number of low-value objects (Bad). Consistent with our hypothesis, we found that Good objects were accurately and quickly targeted, often by a single and direct saccade with a very short latency (<200 ms). The dependence of search times on display size reduced significantly with longer reward training, giving rise to a more efficient search (40 ms/item to 16 ms/item). This object-finding skill showed a large capacity for value-biased objects and was maintained in the long-term memory with no interference from reward learning with other objects. Such object-finding skill, and in particular its large capacity and long term retention, would be crucial for maximizing rewards and biological fitness throughout life where many objects are experienced continuously and/or intermittently.

Components of reward-driven attentional capture.

Recent research reported that task-irrelevant colors captured attention if these colors previously served as search targets and received high monetary reward. We showed that both monetary reward and value-independent mechanisms influenced selective attention. Participants searched for two potential target colors among distractor colors in the training phase. Subsequently, they searched for a shape singleton in a testing phase. Experiment 1 found that participants were slower in the testing phase if a distractor of a previous target color was present rather than absent. Such slowing was observed even when no monetary reward was used during training. Experiment 2 associated monetary rewards with the target colors during the training phase. Participants were faster finding the target associated with higher monetary reward. However, reward training did not yield value-dependent attentional capture in the testing phase. Attentional capture by the previous target colors was not significantly greater for the previously high-reward color than the previously low or no-reward color. These findings revealed both the power and limitations of monetary reward on attention. Although monetary reward can increase attentional priority for the high-reward target during training, subsequent attentional capture effects may not be reward-based, but reflect, in part, attentional capture by previous targets.

Reward memory relieves anxiety-related behavior through synaptic strengthening and protein kinase C in dentate gyrus.

Anxiety disorders are presumably associated with negative memory. Psychological therapies are widely used to treat this mental deficit in human beings based on the view that positive memory competes with negative memory and relieves anxiety status. Cellular and molecular processes underlying psychological therapies remain elusive. Therefore, we have investigated its mechanisms based on a mouse model in which food reward at one open-arm of the elevated plus-maze was used for training mice to form reward memory and challenge the open arms. Mice with the reward training showed increased entries and stay time in reward open-arm versus neutral open-arm as well as in open-arms versus closed-arms. Accompanying with reward memory formation and anxiety relief, glutamatergic synaptic transmission in dentate gyrus in vivo and dendritic spines in granule cells became upregulated. This synaptic up-regulation was accompanied by the expression of more protein kinase C (PKC) in the dendritic spines. The inhibition of PKC by chelerythrine impaired the formation of reward memory, the relief of anxiety-related behavior and the up-regulation of glutamate synapses. Our results suggest that reward-induced positive memory relieves mouse anxiety-related behavior by strengthening synaptic efficacy and PKC in the hippocampus, which imply the underlying cellular and molecular processes involved in the beneficial effects of psychological therapies treating anxiety disorders.

Cognitive bias in rats is not influenced by oxytocin.

The effect of oxytocin on cognitive bias was investigated in rats in a modified conditioned place preference paradigm. Fifteen male rats were trained to discriminate between two different cue combinations, one paired with palatable foods (reward training), and the other paired with unpalatable food (aversive training). Next, their reactions to two ambiguous cue combinations were evaluated and their latency to contact the goal pot recorded. Rats were injected with either oxytocin (OT) or saline with the prediction that rats administered OT would display a shorter average latency to approach on ambiguous trials. There was no significant difference between latencies to approach on ambiguous trials compared to reward trials, but the rats were significantly slower on the aversive compared to the ambiguous conditions. Oxytocin did not affect approach time; however, it was unclear, after follow-up testing, whether the OT doses tested were sufficient to produce the desired effects on cognitive bias. Future research should consider this possibility.

A further call to action: training as a policy issue in court interpreting

This article gathers research from three studies conducted by industry stakeholders in US court interpreting – research which provides a blueprint for prioritising quality in courtroom language access and which concretely links court interpreter training to policy decisions in the areas of language access and interpreter certification testing. The first study examines training experiences of Spanish/English court interpreters in one US state (Wisconsin); the second surveys practising court interpreters in the same state to demarcate specific skill domains and content in which court interpreters wish to receive training; and the third study examines failure rates on the state-level oral court interpreting exams on a national level over a 15-year period, suggesting some key strategies to mitigate such failure. In light of the aforementioned studies, as well as in response to the National Center for State Court’s recent publication entitled A National Call to Action, this article represents a further call to action, beseeching educators and policymakers to create meaningful training opportunities, to acknowledge the relationship between lack of training and widespread oral exam failure, and to reward and incentivise training and credentialing through proactive policy decisions.

Arc visualization of odor objects reveals experience-dependent ensemble sharpening, separation, and merging in anterior piriform cortex in adult rat.

Visualization using the immediate early gene Arc revealed sparser and more robust odor representations in the anterior piriform cortex of adult rats when odor was associated with water reward over 2-3 d. Rewarded odor "mixtures" resulted in rats responding to either component odor similarly, and, correspondingly, the odor representations became more similar as indexed by increased overlap in piriform Arc-expressing (Arc(+)) pyramidal neurons. The increased overlap was consistent with the rats' generalization from component odors. Discriminating among highly similar odor mixtures for reward led to increased differentiation of the neural representations as indexed by a reduction in overlap for piriform Arc(+) pyramidal neurons after training. Similar odor mixture discrimination also required more trials to criterion. The visible reduction in the overlap of odor representations indexes pattern separation. The Arc visualization of odor representations in the anterior piriform network suggests that odor objects are widely distributed representations and can be rapidly modified by reward training in adult rats. We suggest that dynamic changes such as those observed here in piriform odor encoding are at the heart of perceptual learning and reflect the continuing plastic nature of mature associative cortex as an outcome of successful problem solving.

Contingency-based emotional resilience: effort-based reward training and flexible coping lead to adaptive responses to uncertainty in male rats.

Emotional resilience enhances an animal's ability to maintain physiological allostasis and adaptive responses in the midst of challenges ranging from cognitive uncertainty to chronic stress. In the current study, neurobiological factors related to strategic responses to uncertainty produced by prediction errors were investigated by initially profiling male rats as passive, active or flexible copers (n = 12 each group) and assigning to either a contingency-trained or non-contingency trained group. Animals were subsequently trained in a spatial learning task so that problem solving strategies in the final probe task, as well-various biomarkers of brain activation and plasticity in brain areas associated with cognition and emotional regulation, could be assessed. Additionally, fecal samples were collected to further determine markers of stress responsivity and emotional resilience. Results indicated that contingency-trained rats exhibited more adaptive responses in the probe trial (e.g., fewer interrupted grooming sequences and more targeted search strategies) than the noncontingent-trained rats; additionally, increased DHEA/CORT ratios were observed in the contingent-trained animals. Diminished activation of the habenula (i.e., fos-immunoreactivity) was correlated with resilience factors such as increased levels of DHEA metabolites during cognitive training. Of the three coping profiles, flexible copers exhibited enhanced neuroplasticity (i.e., increased dentate gyrus doublecortin-immunoreactivity) compared to the more consistently responding active and passive copers. Thus, in the current study, contingency training via effort-based reward (EBR) training, enhanced by a flexible coping style, provided neurobiological resilience and adaptive responses to prediction errors in the final probe trial. These findings have implications for psychiatric illnesses that are influenced by altered stress responses and decision-making abilities (e.g., depression).

Effort-Based Reward (EBR) training enhances neurobiological efficiency in a problem-solving task: Insights for depression therapies

Effort-Based Reward (EBR) training strengthens associations between effort and rewards, leading to increased persistence in an unsolvable task when compared to control animals. EBR training involves placing animals in a test apparatus in which they are trained to dig in mounds to retrieve froot loop rewards (contingent group); these animals are compared to control animals that are given the same number of rewards, regardless of expended effort (noncontingent group). In the current study, the effect of EBR training on performance in a spatial task (Dry Land Maze) was explored to determine cognitive resilience during behavioral testing. Additionally, animals received BrdU injections during training to assess the role of neurogenesis on subsequent behavioral performance. Following the probe test, animals were perfused so that fos-immunoreactive (ir) cells in the hippocampus and cortical areas could be assessed. Behavioral results indicated that contingent rats were approximately 50% more efficient in locating and interacting with the previous baited well during the probe test than noncontingent animals, recruiting approximately 20% less c-fos ir-cells in the insular cortex, retrosplenial cortex, and dentate gyrus. A multidimensional scaling analysis grouped noncontingent animals together in a quadrant characterized by high latencies to find the previous baited well and higher ir-cell activation in the aforementioned areas. Thus, our data support the hypothesis that the EBR training enhances both cognitive functioning and emotional regulation during challenging events. Considering the ongoing controversy about the efficacy of pharmacological interventions in treating depression, the EBR model provides a valuable alternative for the investigation of the neurobiology of mood disorders.

Aquarium Studies on the Ability of Potential Predators to Learn to Avoid Humbug Damselfish, Dascyllus aruanus (Pisces, Pomacentridae) as Prey

Five species of potential predators of D. aruanus were trained in aquaria using a simple reward versus no-reward training technique in which D. aruanus (no-reward) and a variety of alternative prey species (reward) were presented simultaneously to the former. All the predators tested exhibited an ability to learn to approach the reward species of fish in preference to D. aruanus. Results are discussed in relation to the recently proposed theory that potential predators may learn in the field not to attack D. aruanus but to concentrate on alternative and more easily caught prey.

Opposite effects of amphetamine self-administration experience on dendritic spines in the medial and orbital prefrontal cortex.

We studied the long-term effects of amphetamine self-administration experience (or sucrose reward training) on dendritic morphology (spine density) in nucleus accumbens (Nacc), medial (MPC) and orbital prefrontal cortex (OFC), and hippocampus (CA1 and dentate). Independent groups of rats were trained under a continuous schedule of reinforcement to nose-poke for infusions of amphetamine (0.125 mg/kg/inf) or to receive sucrose pellets during 2 h daily test sessions for 14-20 days. One month after the last training session, the brains were collected and processed for Golgi-Cox staining. We found that: (i) amphetamine self-administration experience selectively increased spine density on medium spiny neurons in the Nacc and on pyramidal neurons in the MPC; (ii) in contrast, amphetamine self-administration decreased spine density in the OFC, whereas sucrose-reward training increased spine density; and (iii) both amphetamine self-administration and sucrose-reward experience increased spines in the CA1, but had no effect in the dentate gyrus. Thus, amphetamine self-administration experience produces long-lasting and regionally-selective morphological alterations in rat forebrain--alterations that may underlie some of the persistent psychomotor, cognitive and motivational consequences of chronic drug exposure.

A neural network underlying individual differences in emotion and aggression in male golden hamsters

In rodents, aggressive behavior can be altered by experimental manipulations of emotional responsiveness. The goal of this study was to identify characteristics of emotional reactivity associated with individual differences in aggressive behavior and their integration within a common neural network. Male golden hamsters were first screened for offensive aggression. Then, the animals were trained through immediate reinforcement and tested for their adaptation to a delayed reward. Similar protocols have been used to test behaviors associated with frustration. At first, all hamsters showed increased frequency of bar pressing per reward during delayed reinforcement. However, Low-Aggression animals were able to adapt to the delay and showed a decreased rate of bar pressing per reward within 5 days. In contrast, High-Aggression animals maintained a high rate of bar pressing per reward. In addition, brains were collected after immediate reward training or delayed reward testing, and labeled for pCREB-immunoreactivity as a marker of trans-synaptic activity. In High-Aggression individuals, elevated density of cyclic AMP response element binding protein, phosphorylated (pCREB) immunostaining was found within the anterior hypothalamus, an area critical to the control of aggression. Delayed reinforcement was associated with enhanced pCREB immunostaining within the central amygdala, medial amygdala and preoptic area/hypothalamus continuum. Further analysis of the data also showed a positive correlation in labeling density between the lateral septum and the anterior hypothalamus, specifically in Low-Aggression animals exposed to delayed reward. Therefore, as High-Aggression individuals lack control of their emotional reactivity, they are also characterized by a de-synchronization between the inhibitory output of the septum and the aggression areas of the hypothalamus. Finally, our data also show that frustration is associated with an extensive activation of the preoptic area/hypothalamus continuum and amygdala.

GABA immunoreactivity in mouse barrel field after aversive and appetitive classical conditioning training involving facial vibrissae

We have previously reported that a classical conditioning paradigm involving stimulation of a row of facial vibrissae produced an expansion of the cortical representation of the “trained row”, labeled with 2-deoxyglucose (2DG), in layer IV of the barrel field. The present study has examined the pattern of GABA immunoreactivity (GABA-IR) in the cortical representation of row B of the facial vibrissae after (i) 3 days of aversive training, and (ii) 2 months of appetitive training, where stimulation of row B of vibrissae on one side of the snout was used as a conditioned stimulus. The most notable observation was a greater density of GABA-IR cells concentrated in the hollows of the “trained row” B barrels compared to the hollows in the barrel field of the opposite hemisphere in the same mouse. After aversive training, we noted a 2-fold increase in the density of GABA-IR neurons in the hollows of row B; after reward training, the increase amounted to 49%. In contrast, GABA-IR was unchanged in the control groups, which received only stimulation of vibrissae without the unconditioned stimulus. The classification of labeled neurons according to size revealed that the increase in density of GABA-IR neurons was confined to the small (12–15 μm) diameter group. We concluded that the GABAergic system undergoes up-regulation, after both associative learning paradigms, and that the population of small, GABAergic neurons plays an active role in use-dependent plasticity.

Does reward increase or decrease creativity?

Two studies involving 504 school children investigated why behaviorists and cognitively oriented investigators have come to opposite conclusions about reward's erects on creativity. A monetary reward for a high degree of divergent thought in 1 task (word construction) increased children's subsequent originality in a different task (picture drawing). The same reward, made contingent on a low degree of divergent thought, reduced this generalized originality. These effects were eliminated by using a large reward and were restored by keeping the large reward out of the children's sight. The results suggest that reward training increases generalized creativity when (a) a high degree of divergent thought is required and (b) the reward is presented in not too salient a fashion

Partial reinforcement delayed extinction effect after regularly alternating reward training

When extinction is delayed very long, the superior resistance to extinction of the random schedule group relative to the alternating schedule group disappears (partial reinforcement delayed extinction effect, PRDE). Two experiments assessed the effects of reinforcement/nonreinforcement on Trial 1 on the PRDE. Following extended partial reinforcement acquisition training in a runway, rats received extinction training after a short (1-day) or long (23-day) retention interval. The schedules used in Experiment 1 were: a single-alternation (SA) schedule beginning each day with a rewarded (r) trial, for Group r-SA; an SA schedule beginning with a nonrewarded (n) trial, for Group n-SA; and a random (Rd) schedule, for Group Rd. The schedules and group names used in Experiment 2 were r-SA, Rd, and r-Rd. The results were that (1) rats given r-SA schedules yielded considerable resistance under delayed extinction, (2) those given Rd and r-Rd schedules showed a decline in resistance to extinction over a long retention interval, (3) those given the n-SA schedule showed relatively low resistance at both retention intervals, although retention deficit was not greater than in the case of the Rd schedule, and thus, (4) the PRDE was found in both experiments, although only weakly in Experiment 1. The results indicated that a regularly alternating reward pattern was a more important determinant than was type of reward on Trial 1 for the PRDE. The PRDE due to differential retention deficits among schedules is discussed on the basis of dual-process associative sequential mechanisms and cognitive rule-encoding mechanisms.

Single unit activity of locus coeruleus neurons in the freely moving cat: II. Conditioning and pharmacologic studies

A series of experiments were carried out in which the single unit activity of presumed noradrenergic (NE) neurons in the area of the locus coeruleus (LC) was examined in freely moving cats during two conditioning paradigms and in response to pharmacologic manipulations relevant to anxiety. LC unit activity was examined during conditioned emotional response (CER) and conditioned food reward (CFR) training. During CER training, LC units showed a large increase in activity in response to a stimulus paired with a noxious air puff, whereas no increase in unit activity was seen in response to a stimulus not paired with the air puff (both comparisons relative to their appropriate control conditions). By contrast, during CFR training, a stimulus paired with a rewarding food delivery did not elicit a significant increase in LC unit activity relative to its appropriate control condition. Therefore, NE units in the LC greatly increase their activity in response to a stimulus that predicts the occurrence of a noxious event, but not in response to a stimulus that predicts the occurrence of a rewarding event. Administration of the anxiolytic drug diazepam (0.25 and 2.0 mg/kg, i.p.) had no significant effect on the spontaneous activity of LC neurons, but significantly reduced the excitatory response of LC neurons to simple stimuli. Administration of the anxiogenic drug yohimbine (2.0 mg/kg, i.p.) significantly increased the spontaneous activity of LC neurons. These results support the hypothesis that LC neurons play a role in aversive but not appetitive conditioning, and are consistent with the hypothesis that these neurons may play a role in anxiety. These data are discussed within the broader context of LC neurons mediating the organism's adaptive response to environmental or physiological challenges.

Books-Received

Books-Received Get access Ecological Genetics: The Interface.— Peter F. Brussard (ed.). 1978. Springer-Verlag, New York, vii + 247 pp. $22.80.—Twelve chapters on the evolution of ecological parameters, coadaptarion, enzyme variation, hypoxia, sexual selection and genetics of Hawaiian and other Drosophila, speciation in field crickets, snail genetics, plant demography and genetics, and population differentiation, reproduced from typescript. Ecological Genetics: The Interface.— Peter F. Brussard (ed.). 1978. Springer-Verlag, New York, vii + 247 pp. $22.80.—Twelve chapters on the evolution of ecological parameters, coadaptarion, enzyme variation, hypoxia, sexual selection and genetics of Hawaiian and other Drosophila, speciation in field crickets, snail genetics, plant demography and genetics, and population differentiation, reproduced from typescript. Life Cycles: An Evolutionary Approach to the Physiology of Reproduction, Development and Ageing.— Peter Calow. 1978. Chapman and Hall, London, distributed by Halsted Press, John Wiley & Sons, New York, ix + 164 pp. $14.95.—A wideranging synthetic treatment of prokaryotes, protists, plants, and animals. Animal Learning: Survey and Analysis.— M. E. Bitterman, V. M. LoLordo, J. Bruce Overmier, Michael E. Rashotte 1979. Plenum Press, New York, xi + 510 pp. $42.50.—Covers conditioning, reward training, and allied topics. Fine Structure of Parasitic Protozoa: An Atlas of Micrographs, Drawings and Diagrams.— E. Scholtyseck 1979. Springer-Verlag, New York, vii + 206 pp. $39.80.—Illustrations of the ultrastructure of representative non-ciliate parasites. Dispersal Centres of Sphingidae (Lepidoptera) in the Neotropical Region.— Harald Schreiber. 1978. Biogeographica, Vol. 10; W. Junk, The Hague and Boston. 195 pp.—An argument for the existence of 18 “dispersal centres” in the Neotropics, based on sphingid distribution, of which “the majority” are congruent with those of Miiller based on terrestrial vertebrates. American Spiders.— Willis J. Gertsch. Second edition, 1979. Van Nostrand Reinhold, New York, xiii + 274 pp. $24.95.—A revised edition (after thirty years) of this classic popular account of the natural history of the North American spider fauna; with numerous new color plates. Behavioral Biology of Aplysia: A Contribution to the Comparative Study of Opisthobranch Molluscs. — Eric R. Kandel. 1979. W. H. Freeman and Co., San Francisco, xiii + 463 pp. No price supplied. —Survey of the sensory structure and function, development, and behavior of marine snails. Contrasts in Behavior.— Ernst S. Reese Frederick J. Lighter (eds.). 1979. John Wiley and Sons, New York, xi + 406 pp. $27.50.—Twelve chapters on comparative aspects on the reproductive, communicative, regulatory, feeding, and social behavior of terrestrial and aquatic vertebrates. Why the Dinosaurs Became Extinct.— J. L. Cloudsley-Thompson. 1978. Meadowfield Press, Shildon, England DL4 2QZ. 86 pp. $8.40.—Stories for swapping on a wintry evening. Turtles: Perspectives and Research.— Marion Harless and Henry Morlock (eds.). 1979. John Wiley and Sons, New York, xiv + 695 pp. $45.00.—A general survey of turtle biology, with a single, brief, and less than up-to-date chapter on “Taxonomy, Evolution, and Zoogeography.” Das evolutive Plateau Saugetier: Origin and Early Evolution of Mammals.— D. Starck, H. F. Moeller, W. Maier, and G. Hahn 1978. Sonderbände des Naturwissenschaftlichen Vereins in Hamburg, No. 3; Verlag Paul Parey, Hamburg. 95 pp. 26 marks.—Proceedings of the “22. Phylogenetisches Symposion” (1977) with chapters by the four authors, respectively, on monotremes, marsupials, the tribosphenic molar, and multituberculates. Sirenian Evolution in the North Pacific Ocean.— Daryl P. Domning 1978. Univ. of California Publ. in Geol. Sci., Vol. 118; University of California Press, Berkeley. 187 pp. $9.00.—A monographic study pertaining to material published in SZ 25:352-362. Kangaroo Rats: Intraspecific Variation in Dipodomys spectabilis Merriam and Dipodomys deserti Stephens.— Iyad A. Nader. 1978. Illinois Biological Monographs 49, University of Illinois Press, Urbana. 116 pp. $12.50.—Study of 14 skull measurements, six external measurements, and color in seven and four subspecies, respectively. Sensory Systems of Primates.— Charles R. Noback (ed.). 1978. Plenum Press, New York, xiii + 207 pp. $25.00.—Another volume in the “Advances in Primatology” series. Extra-ocular Photosensitivity.— N. Millott 1978. Meadowfield Press, Shildon, England DL4 2QZ. 52 pp. $8.40.—Popularized survey of the structural, biochemical, and physiological basis of light receptors other than eyes. Analysis of Ecological Systems.— David J. Horn, Rodger D. Mitchell, Gordon R. Stairs (eds.). 1979. Ohio State University Press, Columbus, ix + 312 pp. $27.50.—Chapters of evolutionary interest include “Fitness, Survival, and Optimality” by R. C. Lewontin, “Darwinian Analyses: The New Natural History” by Rodger D. Mitchell and Mary B. Williams, “The Ecology of Colonizing Species” by D. C. Embree, “Niche Segregation in Desert Lizards” by Erik R. Pianka, Raymond B. Huey, and Lawrence R. Lawlor, and “Development of Theory in Insect-Plant Interactions” by Lawrence E. Gilbert. Systematic Biology, Volume 28, Issue 3, September 1979, Pages 412–413, https://doi.org/10.1093/sysbio/28.3.412 Published: 01 September 1979

マウスの回避学習と報酬学習に及ぼすvinblastineの腹腔内投与の影響

マウスの回避学習と報酬学習に及ぼすvinblastineの腹腔内投与の影響

Resistance to satiation of consummatory and instrumental performance

In three experiments rats received training in a straight alley under high hunger and then were tested satiated. Both eating and running continued to occur under satiation, but the two responses were not completely correlated, and continued running did not depend upon continued eating. Further, groups differed in their eating behavior, although all experienced the same satiation procedure, suggesting that eating under satiation is not just a reflection of incomplete satiation. Resistance to satiation of the running response was greater following partial reward than following consistant reward and tended to be greater following small reward training than large reward training, regardless of schedule of reward. Eating during satiation was greater following partial than following consistent reward and was greater if the same reward magnitude was given in satiation as in acquisition than if a different reward magnitude was given. It was suggested that resistance to satiation is an associative phenomenon. Eating and running occur during satiation because the stimuli present during satiation continue to elicit them. The differences between results using rewarded satiation and results using high drive extinction as measures of persistence were attributed to satiation being nonfrustrating.

The learning of hand preferences by squirrel monkey

In a reaching task with Squirrel Monkeys stable hand preferences were established by reward training. The use of a particular hand was brought under the control of a colour cue.