Revisiting the Gain–Loss Separability Assumption in Prospect Theory

A fundamental assumption of prospect theory is gain–loss separability (GLS)—the assertion that the overall utility of a prospect can be expressed as a function of the utilities of its positive and negative components. Violations of GLS may potentially limit the generalization of results from studies of single‐domain prospects to mixed prospects and systematically distort the predictions of the theory. Violations also have implications for how choices with positive and negative components should be presented to decision makers. Previous studies, using different elicitation methods, have documented different rates, and types, of systematic violations of GLS. We discuss the differences between two specific elicitation methods—binary choice and certainty equivalents—and report results of a new study of GLS using both methods and randomly generated prospects. We compare the extent and nature of GLS violations under the two elicitation methods using between‐subject and within‐subject analyses. We find (i) systematic violations of GLS under both methods, (ii) higher rates of violations under choice, (iii) higher sensitivity to the outcomes for the certainty equivalents, which is consistent with the predictions of the scale‐compatibility hypothesis, and (iv) different patterns of violations under the two methods, which are explained by method‐specific preferences. We discuss the psychological mechanisms underlying the findings and the implications for presenting information with gain and loss components. Copyright © 2012 John Wiley & Sons, Ltd.     

Hello/goodbye new families: group work with five looked-after siblings in foster care together awaiting a move to separate adoptive families

This paper describes group work with five siblings aged between three and nine. They were taken into care following severe abuse involving neglect, physical and emotional abuse. In it, we consider the impact of the losses on the network and the children. We explore how Freud, in his paper ‘Mourning and melancholia’ (1917), and others who built on his work, helped us understand the children’s losses. The sibling group was planned in order to address the children’s need to say goodbye to their birth parents, their foster carers and to each other and to prepare them for their individual separate adoptions. The group ran for 18 months and ended when four children had been placed in their adoptive homes; the last child to be adopted was then seen individually until she was also placed. The group work is described with the use of quotes from sessional material to illuminate the processes for these children in facing their complicated and ambivalent losses, the mourning process and their progress towards becoming individuals in their own right rather than enacting fragmented functional parts/roles on behalf of their sibling group as a whole. Their mourning of the loss of each other was complicated by their earlier reliance on each other to manage the difficulties they had faced when surviving their abusive early lives together.     

Self‐Control Moderates Decision‐Making Behavior When Minimizing Losses versus Maximizing Gains

We examined (1) whether people would be more responsive to the delayed consequences of their decisions when attempting to minimize losses than when attempting to maximize gains in a history‐dependent decision‐making task and (2) how trait self‐control would moderate such an effect. In two experiments, participants performed a dynamic decision‐making task where they chose one of two options on each trial. The increasing option always gave a smaller immediate reward but caused future rewards for both options to increase. The decreasing option always gave a larger immediate reward but caused future rewards for both options to decrease. In Experiment 1 where the two options had equivalent expected value in the long run, participants were more prone to select the increasing option, which yielded larger benefits on future trials, in the loss‐minimization condition than in the gain‐maximization condition. Trait self‐control moderated the effect of losses by enhancing the effect for low self‐control participants while attenuating it for high self‐control participants. In Experiment 2 where selecting the increasing option was suboptimal, low self‐control participants still attempted to reduce losses on future trials by selecting the increasing option more often than high self‐control participants. These results suggest that decision makers value delayed consequences of their actions more in a losses domain relative to a gains domain and low self‐control individuals are more susceptible to such an effect. Copyright © 2014 John Wiley & Sons, Ltd.     

The sign effect,systematic devaluations and zero discounting

The sign effect is the steeper discounting of gains compared to losses. However, we see a greater sign effect on an individual level compared to an aggregate level. In this experiment, we compare discounting of gains and losses on an individual and aggregate level, to explore further details about when and to what extent human adults discount. Thirty-one participants went through a computer-based choice-task procedure of hypothetical monetary gains and losses. The results show clear qualitative differences between discounting of gains and losses, adding empirical data to support the sign effect. The results also support previous findings that show that aggregate and individual results do not always correspond. Further, the within-subject details showing zero discounting or nonsystematic changes concerning losses, replicate earlier studies suggesting that discounting of gains and losses involve different reinforcing contingencies. The present study expands on this research area by including verbal reports, supplementing details about the unobserved reinforcing contingencies. Implications of research on discounting may indicate how to deal with decision-making challenges and might shed light on why predictions about complex decision making sometimes fail.     

Determining individual preschoolers' preferences in a group arrangement

This study sought to determine the accuracy of an assessment format in which selection outcomes were delayed and probabilistic; these are unavoidable features of an assessment designed to determine preferences of multiple children simultaneously. During the single arrangement, preference hierarchies were established by having a child repeatedly select from among several foods and by sequentially restricting preferred items from the array. After being taught the associations between colored cards and the same food items, group assessments were conducted with 3 children simultaneously, in which each child chose a card and all children received the food correlated with a randomly selected card from those that had just been selected. The group assessment appeared to be accurate and perhaps more efficient for determining preferences; thus, we posit that this arrangement is suitable for determining context preferences of multiple children simultaneously.     

Asymptotic Densities in Logic and Type Theory

This paper presents a systematic approach for obtaining results from the area of quantitative investigations in logic and type theory. We investigate the proportion between tautologies (inhabited types) of a given length n against the number of all formulas (types) of length n. We investigate an asymptotic behavior of this fraction. Furthermore, we characterize the relation between number of premises of implicational formula (type) and the asymptotic probability of finding such formula among the all ones. We also deal with a distribution of these asymptotic probabilities. Using the same approach we also prove that the probability that randomly chosen fourth order type (or type of the order not greater than 4), which admits decidable lambda definability problem, is zero. Presented by Jacek Malinowski     

Base-rate neglect as a function of base rates in probabilistic contingency learning

When humans predict criterion events based on probabilistic predictors, they often lend excessive weight to the predictor and insufficient weight to the base rate of the criterion event. In an operant analysis, using a matching-to-sample paradigm, Goodie and Fantino (1996) showed that humans exhibit base-rate neglect when predictors are associated with criterion events through physical similarity. In partial replications of their studies, we demonstrated similar effects when the predictors resembled the criterion events in terms of similarly skewed base rates. Participants' predictions were biased toward the more (or less) frequent criterion event following the more (or less) frequent predictor. This finding adds to the growing evidence for pseudocontingencies (Fiedler & Freytag, 2004), a framework that stresses base-rate influences on contingency learning.     

Statistics of Intuitionistic versus Classical Logics

For the given logical calculus we investigate the proportion of the number of true formulas of a certain length n to the number of all formulas of such length. We are especially interested in asymptotic behavior of this fraction when n tends to infinity. If the limit exists it is represented by a real number between 0 and 1 which we may call the density of truth for the investigated logic. In this paper we apply this approach to the intuitionistic logic of one variable with implication and negation. The result is obtained by reducing the problem to the same one of Dummett's intermediate linear logic of one variable (see [2]). Actually, this paper shows the exact density of intuitionistic logic and demonstrates that it covers a substantial part (more than 93%) of classical prepositional calculus. Despite using strictly mathematical means to solve all discussed problems, this paper in fact, may have a philosophical impact on understanding how much the phenomenon of truth is sporadic or frequent in random mathematics sentences.     

Evolution, Behavior Principles, And Developmental Systems: A Review Of Gottlieb’s Synthesizing Nature-nurture: Prenatal Roots Of Instinctive Behavior.

Gottlieb's developmental psychobiology book provides a base for reexamining the place of the experimental analysis of behavior in the life sciences. His experimental program demonstrating the critical function of the environment in the development of a species‐typical behavior helped force an acceptance of probabilistic epigenesis, the acknowledgment that the developmental genome‐environment system is fully interactional. (Indeed, nature vs. nurture is deader than a doornail.) The repercussions for evolutionary biology and the roles and categorizations of genes, behavior, and environment in behavior‐environment relations are explored in light of current knowledge, including specific implications for the experimental analysis of behavior.     

Measuring Probabilistic Reasoning: The Construction of a New Scale Applying Item Response Theory

Probabilistic reasoning skills are important in various contexts. The aim of the present study was to develop a new instrument (the Probabilistic Reasoning Scale – PRS) to accurately measure low levels of probabilistic reasoning ability in order to identify people with difficulties in this domain. Item response theory was applied to construct the scale, and to investigate differential item functioning (i.e., whether the items were invariant) across genders, educational levels, and languages. Additionally, we tested the validity of the scale by investigating the relationships between the PRS and several other measures. The results revealed that the items had a low level of difficulty. Nonetheless, the discriminative measures showed that the items can discriminate between individuals with different trait levels, and the test information function showed that the scale accurately assesses low levels of probabilistic reasoning ability. Additionally, through investigating differential item functioning, the measurement equivalence of the scale at the item level was confirmed for gender, educational status, and language (i.e., Italian and English). Concerning validity, the results showed the expected correlations with numerical skills, math‐related attitudes, statistics achievement, IQ, reasoning skills, and risky choices both in the Italian and British samples. In conclusion, the PRS is an ideal instrument for identifying individuals who struggle with basic probabilistic reasoning, and who could be targeted by specific interventions. Copyright © 2017 John Wiley & Sons, Ltd.