scholarly journals Impaired expected value computations in schizophrenia are associated with a reduced ability to integrate reward probability and magnitude of recent outcomes

2018 ◽  
Author(s):  
Hernaus Dennis ◽  
Michael J. Frank ◽  
Elliot C. Brown ◽  
Jaime K. Brown ◽  
James M. Gold ◽  
...  
Keyword(s):  
Reward Magnitude ◽  
Expected Value ◽  
Familiar Stimulus ◽  
Q Learning ◽  
Stimulus Response ◽  
Hybrid Framework ◽  
Reward Value ◽  
Reward Probability ◽  
Motivational Deficit ◽  
The Difference

ABSTRACTBackgroundMotivational deficits in people with schizophrenia (PSZ) are associated with an inability to integrate the magnitude and probability of previous outcomes. The mechanisms that underlie probability-magnitude integration deficits, however, are poorly understood. We hypothesized that increased reliance on “value-less” stimulus-response associations, in lieu of expected value (EV)-based learning, could drive probability-magnitude integration deficits in PSZ with motivational deficits.MethodsHealthy volunteers (n= 38) and PSZ (n=49) completed a reinforcement learning paradigm consisting of four stimulus pairs. Reward magnitude (3/2/1/0 points) and probability (90%/80%/20%/10%) together determined each stimulus’ EV. Following a learning phase, new and familiar stimulus pairings were presented. Participants were asked to select stimuli with the highest reward value.ResultsPSZ with high motivational deficits made increasingly less optimal choices as the difference in reward value (probability*magnitude) between two competing stimuli increased. Using a previously-validated computational hybrid model, PSZ relied less on EV (“Q-learning”) and more on stimulus-response learning (“actor-critic”), which correlated with SANS motivational deficit severity. PSZ specifically failed to represent reward magnitude, consistent with model demonstrations showing that response tendencies in the actor-critic were preferentially driven by reward probability. ConclusionsProbability-magnitude deficits in PSZ with motivational deficits arise from underutilization of EV in favor of reliance on value-less stimulus-response associations. Consistent with previous work and confirmed by our computational hybrid framework, probability-magnitude integration deficits were driven specifically by a failure to represent reward magnitude. This work reconfirms the importance of decreased Q-learning/increased actor-critic-type learning as an explanatory framework for a range of EV deficits in PSZ.

scholarly journals How informative is Wright's estimator of the number of genes affecting a quantitative character?

Genetics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 235-247 ◽  
Author(s):  
Z B Zeng ◽  
D Houle ◽  
C C Cockerham
Keyword(s):  
Genetic Variance ◽  
Estimation Procedure ◽  
Expected Value ◽  
Allele Frequencies ◽  
Quantitative Character ◽  
Base Population ◽  
Single Population ◽  
Number Of Genes ◽  
Selection Limit ◽  
The Difference

Abstract S. Wright suggested an estimator, m, of the number of loci, m, contributing to the difference in a quantitative character between two differentiated populations, which is calculated from the phenotypic means and variances in the two parental populations and their F1 and F2 hybrids. The same method can also be used to estimate m contributing to the genetic variance within a single population, by using divergent selection to create differentiated lines from the base population. In this paper we systematically examine the utility and problems of this technique under the influences of unequal allelic effects and initial allele frequencies, and linkage, which are known to lead m to underestimate m. In addition, we examine the effects of population size and selection intensity during the generations of selection. During selection, the estimator m rapidly approaches its expected value at the selection limit. With reasonable assumptions about unequal allelic effects and initial allele frequencies, the expected value of m without linkage is likely to be on the order of one-third of the number of genes. The estimates suffer most seriously from linkage. The practical maximum expectation of m is just about the number of chromosomes, considerably less than the "recombination index" which has been assumed to be the upper limit. The estimates are also associated with large sampling variances. An estimator of the variance of m derived by R. Lande substantially underestimates the actual variance. Modifications to the method can ameliorate some of the problems. These include using F3 or later generation variances or the genetic variance in the base population, and replicating the experiments and estimation procedure. However, even in the best of circumstances, information from m is very limited and can be misleading.

Perception of Risk as Related to Choice in a Two-Dimensional Risk Situation

1978 ◽  
Vol 43 (3_suppl) ◽  
pp. 1059-1062 ◽  
Author(s):  
John W. Dickson
Keyword(s):  
Risky Choice ◽  
Expected Value ◽  
Two Dimensions ◽  
Choice Situation ◽  
Two Dimensional ◽  
Objective Risk ◽  
Subjective Risk ◽  
Risk Situation ◽  
The Difference ◽  
Two Alternatives

A risky choice was created by manipulating two dimensions of risk for 21 managers attending a conference. The first dimension varied risk by altering the difference in expected value between two alternatives of widely differing variance. The second dimension varied the expectancy of achieving a particular outcome. Whereas choice was significantly related to both dimensions of risk, it was not significantly related to estimates of the subjective risk inherent in the choice situation. It appears that subjective risk does not mediate between objective risk and choice.

scholarly journals IS DIGIT SUPERIORITY INDISPENSABLE WITH REGARD TO SHORT TERM MEMORY SPAN?

2021 ◽  
Vol 9 (22) ◽  
Keyword(s):  
Short Term Memory ◽  
Memory Span ◽  
Familiar Stimulus ◽  
Short Term ◽  
Superiority Effect ◽  
Term Memory ◽  
Significant Difference ◽  
Color Name ◽  
The Difference ◽  
Familiar Stimuli

It is known that digits have a positive effect on the performance of short term memory (STM) span and it is called the digit superiority effect. This study aims to examine the effect of familiar stimuli (digits, colors, digit names, color names, and words) on STM span. In order to measure STM capacity, a memory span task was used including the digit, word, and color span lists. 91 participants (44 female, 47 male) aged between 18-27 (M = 21,43, SD = 1.50) participated in the study that consisted of three different experiments. Results of Experiment 1 revealed that there was a significant difference between the digit name and word with regard to span size and total span. In Experiment 2 and 3, the main effect of familiar stimulus type on total span and span size was significant, and also the difference between all types of stimuli was significant (Experiment II, digit name>word=color name; Experiment III, digit>digit name>color name>color). The common result obtained from all experiments is that digits are superior with regard to STM span than other familiar stimuli types such as words, color names, colors. This study confirmed that digit superiority effect is indispensable on verbal and visual STM span. Keywords Digit superiority, short term memory, memory span

scholarly journals Analisis Kepuasan Pengguna Website Asuransi Untuk Peningkatan Pelayanan Asuransi Studi Kasus www.Cakrawalaproteksi.Com

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Syafitri Mona Sari ◽  
Firdaus Firdaus ◽  
A. Haidar Mirza
Keyword(s):  
Social Media ◽  
Customer Satisfaction ◽  
Insurance Industry ◽  
Expected Value ◽  
Insurance Company ◽  
Simple Analysis ◽  
Internet Users ◽  
The Difference

Currently, technology has developed quite rapidly and covers all aspects, including in the insurance industry. Almost every insurance company has a website or social media that can be accessed by all internet users as a means of promotion and transactions. PT. Asuransi Cakrawala Proteksi is an insurance company that also carries out promotions through websites and social media. This research will discuss the customer satisfaction of PT. Asuransi Cakrawala Protection with the role of social media. Customer satisfaction is determined by looking at the difference between the actual value received and the expected value using the website and social media Facebook. From calculating the level of customer satisfaction with ServQual dimensions and simple analysis, a strategy will be produced to maintain or increase customer satisfaction.

scholarly journals Budidaya Terung Ungu di Pekarangan di Desa Ciawijapura Kecamatan Susukan Lebak Kabupaten Cirebon

2021 ◽  
Vol 2 (1) ◽  
pp. 39
Author(s):  
Umi Trisnaningsih ◽  
Siti Wahyuni ◽  
Wachdijono Wachdijono
Keyword(s):  
Community Service ◽  
Culture System ◽  
Expected Value ◽  
Family Welfare ◽  
Service Program ◽  
Dry Land ◽  
Before And After ◽  
The Difference

<p><em>Yard land can be used as a family food barn. One of the efforts to overcome the limitations of land is by cultivating in a limited place (bag culture system) such as polybags, pots or used buckets. In Ciawijapura Village, Susukan Lebak </em><em>Sub-district, Cirebon Regency, purple eggplant is commonly cultivated in dry land, as well as in yards. This Community Service Program (</em><em>Pengabdian Kepada Masyarakat/PKM) is aimed at increasing the knowledge of</em><em> Family Welfare Building Motivation Team (</em><em>Tim Penggerak Pembinaan Kesejahteraan Keluarga/TP-PKK</em><em>) cadres and members of Farmer Women Group </em><em>(</em><em>Kelompok Wanita Tani</em><em>/KWT</em><em>) Al Istiqomah about cultivating purple eggplant in a bag culture system. The methods used are training and mentoring. The evaluation results showed that there was a significant increase in knowledge between before and after the training, that is, from 73% to 89% of the total expected value. The participants were able to understand the difference between cultivating purple eggplant on land and in a bag culture system.</em></p>

scholarly journals Expected Reward Value and Reward Uncertainty Have Temporally Dissociable Effects on Memory Formation

2019 ◽  
Vol 31 (10) ◽  
pp. 1443-1454 ◽  
Author(s):  
Jessica K. Stanek ◽  
Kathryn C. Dickerson ◽  
Kimberly S. Chiew ◽  
Nathaniel J. Clement ◽  
R. Alison Adcock
Keyword(s):  
Dopamine Release ◽  
Behavioral Effect ◽  
Memory Formation ◽  
Dopamine Neurons ◽  
Reward Anticipation ◽  
Memory Modulation ◽  
Reward Value ◽  
Reward Probability ◽  
Mechanisms Of Memory ◽  
The Impact

Anticipating rewards has been shown to enhance memory formation. Although substantial evidence implicates dopamine in this behavioral effect, the precise mechanisms remain ambiguous. Because dopamine nuclei have been associated with two distinct physiological signatures of reward prediction, we hypothesized two dissociable effects on memory formation. These two signatures are a phasic dopamine response immediately following a reward cue that encodes its expected value and a sustained, ramping response that has been demonstrated during high reward uncertainty [Fiorillo, C. D., Tobler, P. N., & Schultz, W. Discrete coding of reward probability and uncertainty by dopamine neurons. Science, 299, 1898–1902, 2003]. Here, we show in humans that the impact of reward anticipation on memory for an event depends on its timing relative to these physiological signatures. By manipulating reward probability (100%, 50%, or 0%) and the timing of the event to be encoded (just after the reward cue versus just before expected reward outcome), we demonstrated the predicted double dissociation: Early during reward anticipation, memory formation was improved by increased expected reward value, whereas late during reward anticipation, memory formation was enhanced by reward uncertainty. Notably, although the memory benefits of high expected reward in the early interval were consolidation dependent, the memory benefits of high uncertainty in the later interval were not. These findings support the view that expected reward benefits memory consolidation via phasic dopamine release. The novel finding of a distinct memory enhancement, temporally consistent with sustained anticipatory dopamine release, points toward new mechanisms of memory modulation by reward now ripe for further investigation.

scholarly journals Reward Magnitude Coding in Primate Amygdala Neurons

2010 ◽  
Vol 104 (6) ◽  
pp. 3424-3432 ◽  
Author(s):  
Maria A. Bermudez ◽  
Wolfram Schultz
Keyword(s):  
Reward Magnitude ◽  
Fruit Juice ◽  
Probability Distributions ◽  
Important Variable ◽  
Reward Delivery ◽  
Economic Decision Making ◽  
Reward Value ◽  
Value Coding ◽  
Characteristic Component ◽  
Increased Activity

Animals assess the values of rewards to learn and choose the best possible outcomes. We studied how single neurons in the primate amygdala coded reward magnitude, an important variable determining the value of rewards. A single, Pavlovian-conditioned visual stimulus predicted fruit juice to be delivered with one of three equiprobable volumes ( P = 1/3). A population of amygdala neurons showed increased activity after reward delivery, and almost one half of these responses covaried with reward magnitude in a monotonically increasing or decreasing fashion. A subset of the reward responding neurons were tested with two different probability distributions of reward magnitude; the reward responses in almost one half of them adapted to the predicted distribution and thus showed reference-dependent coding. These data suggest parametric reward value coding in the amygdala as a characteristic component of its function in reinforcement learning and economic decision making.

scholarly journals Selection and subsequent analysis of sib pair data for QTL detection

2001 ◽  
Vol 78 (2) ◽  
pp. 177-186 ◽  
Author(s):  
DIMITRIOS G. CHATZIPLIS ◽  
HENNING HAMANN ◽  
CHRIS S. HALEY
Keyword(s):  
Robust Regression ◽  
Expected Value ◽  
Regression Method ◽  
Qtl Detection ◽  
Selection Scheme ◽  
Phenotypic Differences ◽  
Effective Selection ◽  
The Difference ◽  
Trait Locus ◽  
Sib Pairs

Haseman and Elston (1972) developed a robust regression method for the detection of linkage between a marker and a quantitative trait locus (QTL) using sib pair data. The principle underlying this method is that the difference in phenotypes between pairs of sibs becomes larger as they share a decreasing number of alleles at a particular QTL identical by descent (IBD) from their parents. In this case, phenotypically very different sibs will also on average share a proportion of alleles IBD at any marker linked to the QTL that is lower than the expected value of 0·5. Thus, the deviation of the proportion of marker alleles IBD from the expected value in pairs of sibs selected to be phenotypically different (i.e. discordant) can provide a test for the presence of a QTL. A simple regression method for QTL detection in sib pairs selected for high phenotypic differences is presented here. The power of the analytical method was found to be greater than the power obtained using the standard analysis when samples of sib pairs with high phenotypic differences were used. However, the use of discordant sib pairs was found to be less powerful for QTL detection than alternative selective genotyping schemes based on the phenotypic values of the sibs except with intense selection, when its advantage was only marginal. The most effective selection scheme overall was the use of sib pairs from entire families selected on the basis of high within-family variance for the trait in question. There is little effect of selection on QTL position estimates, which are in good agreement with the simulated values. However, QTL variance estimates are biased to a greater or lesser degree, depending on the selection method.

scholarly journals Reward associations do not explain transitive inference performance in monkeys

2018 ◽  
Author(s):  
Greg Jensen ◽  
Yelda Alkan ◽  
Vincent P Ferrera ◽  
Herbert S Terrace
Keyword(s):  
Reward Magnitude ◽  
Mental Representations ◽  
Transitive Inference ◽  
Rule Based ◽  
Correct Rule ◽  
Reward Value ◽  
The Face ◽  
Countervailing Incentives

The observation that monkeys appear to make transitive inferences has been taken as evidence of their ability to form and manipulate mental representations. However, alternative explanations have been proposed arguing that transitive inference performance based on expected or experienced reward value. To test the contribution of reward value to monkeys’ behavior in TI paradigms, we performed two experiments in which we manipulated the amount of reward associated with each item in an ordered list. In these experiments, monkeys were presented with pairs of items drawn from the list, and delivered rewards if subjects selected the item with the earlier list rank. When reward magnitude was biased to favor later list items, correct responding was reduced. However, monkeys eventually learned to make correct rule-based choices despite countervailing incentives. The results demonstrate that monkeys’ performance in TI paradigms is not driven solely by expected reward, but that they are able to make appropriate inferences in the face of discordant reward associations.

scholarly journals Analisis Kepuasan Pengguna Website Asuransi Untuk Peningkatan Pelayanan Asuransi Studi Kasus www.Cakrawalaproteksi.Com

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Syafitri Mona Sari ◽  
Firdaus Firdaus ◽  
A. Haidar Mirza
Keyword(s):  
Social Media ◽  
Customer Satisfaction ◽  
Insurance Industry ◽  
Expected Value ◽  
Insurance Company ◽  
Simple Analysis ◽  
Internet Users ◽  
The Difference

Currently, technology has developed quite rapidly and covers all aspects, including in the insurance industry. Almost every insurance company has a website or social media that can be accessed by all internet users as a means of promotion and transactions. PT. Asuransi Cakrawala Proteksi is an insurance company that also carries out promotions through websites and social media. This research will discuss the customer satisfaction of PT. Asuransi Cakrawala Protection with the role of social media. Customer satisfaction is determined by looking at the difference between the actual value received and the expected value using the website and social media Facebook. From calculating the level of customer satisfaction with ServQual dimensions and simple analysis, a strategy will be produced to maintain or increase customer satisfaction.

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