Gain-loss asymmetry in human experiential tasks

<p>Prospect Theory models behaviour in one-off decisions where outcomes are described. Prospect Theory describes risk aversion when the choice is between gains and risk seeking when the choice is between losses. This asymmetry is known as the reflection effect. In choices about experienced outcomes, individuals show risk seeking for gains and risk aversion for losses. This change in the direction of gain-loss asymmetry is known as the description-experience gap. Across eight experiments, we examined gain-loss asymmetry in two experiential choice procedures. We compared the obtained results with predictions derived from Prospect Theory and the description-experience gap literature. In Study 1, we evaluated the predictions of the reversed reflection effect in probability discounting. Probability discounting is loss in reinforcer value as a function of uncertainty. In typical tasks measuring discounting, participants choose between smaller, certain amounts and a larger amount at one of several probabilities. In choice from description, most participants show a gain-loss asymmetry consistent with the predictions of the reflection effect, discounting gains more steeply than losses. Across three experiments, we examined whether gain-loss asymmetry also occurred when participants experienced the outcomes they chose, when they chose between two uncertain options, and when these two contexts were combined. Across all of the above contexts, no consistent mean difference in discounting of gains and losses was observed. Rather, in most of the tasks that provided experienced outcomes, the participants showed steeper discounting in the first condition completed, whether it involved choices about gains or losses. Furthermore, subsequent conditions produced shallower discounting, but notably, not shallower than choice based on the expected value of the options. In Studies 2 and 3, we followed-up on this order effect by providing the participants with experience of probabilistic outcomes before the discounting tasks. Participants discounted losses more steeply than gains, consistent with the predictions of a reversed reflection effect. In Study 2, we examined gain-loss asymmetry in a rapid-acquisition choice procedure using concurrent variable-interval schedules – the Auckland Card Task. Participants repeatedly chose between two decks of cards that varied in the frequency or magnitude of available gains or losses. Participants were more sensitive to changes in gain than loss frequency between the two decks, consistent with the predictions of a reversed reflection effect, while sensitivity to gain and loss magnitude did not show an asymmetry. We found a novel asymmetry in the local effects of gains and losses. In the frequency tasks, gains disrupted the general pattern of responding more than losses. In the magnitude tasks, varying the magnitude of losses had a bigger effect on local-level patterns following outcomes than varying the magnitude of gains. Across the two tasks we observed patterns of gain-loss asymmetry consistent with the predictions of a reversed reflection effect. We also observed several inconsistencies, particularly when comparing behaviour to choices that would maximize the expected returns. Our research suggested that sufficient exposure to chance outcomes and ensuring delivery of scheduled events are key challenges in further refinement of experiential choice in human operant tasks.</p>

Gain-loss asymmetry in human experiential tasks

<p>Prospect Theory models behaviour in one-off decisions where outcomes are described. Prospect Theory describes risk aversion when the choice is between gains and risk seeking when the choice is between losses. This asymmetry is known as the reflection effect. In choices about experienced outcomes, individuals show risk seeking for gains and risk aversion for losses. This change in the direction of gain-loss asymmetry is known as the description-experience gap. Across eight experiments, we examined gain-loss asymmetry in two experiential choice procedures. We compared the obtained results with predictions derived from Prospect Theory and the description-experience gap literature. In Study 1, we evaluated the predictions of the reversed reflection effect in probability discounting. Probability discounting is loss in reinforcer value as a function of uncertainty. In typical tasks measuring discounting, participants choose between smaller, certain amounts and a larger amount at one of several probabilities. In choice from description, most participants show a gain-loss asymmetry consistent with the predictions of the reflection effect, discounting gains more steeply than losses. Across three experiments, we examined whether gain-loss asymmetry also occurred when participants experienced the outcomes they chose, when they chose between two uncertain options, and when these two contexts were combined. Across all of the above contexts, no consistent mean difference in discounting of gains and losses was observed. Rather, in most of the tasks that provided experienced outcomes, the participants showed steeper discounting in the first condition completed, whether it involved choices about gains or losses. Furthermore, subsequent conditions produced shallower discounting, but notably, not shallower than choice based on the expected value of the options. In Studies 2 and 3, we followed-up on this order effect by providing the participants with experience of probabilistic outcomes before the discounting tasks. Participants discounted losses more steeply than gains, consistent with the predictions of a reversed reflection effect. In Study 2, we examined gain-loss asymmetry in a rapid-acquisition choice procedure using concurrent variable-interval schedules – the Auckland Card Task. Participants repeatedly chose between two decks of cards that varied in the frequency or magnitude of available gains or losses. Participants were more sensitive to changes in gain than loss frequency between the two decks, consistent with the predictions of a reversed reflection effect, while sensitivity to gain and loss magnitude did not show an asymmetry. We found a novel asymmetry in the local effects of gains and losses. In the frequency tasks, gains disrupted the general pattern of responding more than losses. In the magnitude tasks, varying the magnitude of losses had a bigger effect on local-level patterns following outcomes than varying the magnitude of gains. Across the two tasks we observed patterns of gain-loss asymmetry consistent with the predictions of a reversed reflection effect. We also observed several inconsistencies, particularly when comparing behaviour to choices that would maximize the expected returns. Our research suggested that sufficient exposure to chance outcomes and ensuring delivery of scheduled events are key challenges in further refinement of experiential choice in human operant tasks.</p>

Optogenetic stimulation of striatal patches modifies habit formation and inhibits dopamine release

Habits are inflexible behaviors that develop after extensive repetition, and overreliance on habits is a hallmark of many pathological states. The striatum is involved in the transition from flexible to inflexible responding, and interspersed throughout the striatum are patches, or striosomes, which make up ~15% of the volume of the striatum relative to the surrounding matrix compartment. Previous studies have suggested that patches are necessary for normal habit formation, but it remains unknown exactly how patches contribute to habit formation and expression. Here, using optogenetics, we stimulated striatal patches in Sepw1-NP67 mice during variable interval training (VI60), which is used to establish habitual responding. We found that activation of patches at reward retrieval resulted in elevated responding during VI60 training by modifying the pattern of head entry and pressing. Further, this optogenetic manipulation reduced subsequent responding following reinforcer devaluation, suggesting modified habit formation. However, patch stimulation did not generally increase extinction rates during a subsequent extinction probe, but did result in a small ‘extinction burst’, further suggesting goal-directed behavior. On the other hand, this manipulation had no effect in omission trials, where mice had to withhold responses to obtain rewards. Finally, we utilized fast-scan cyclic voltammetry to investigate how patch activation modifies evoked striatal dopamine release and found that optogenetic activation of patch projections to the substantia nigra pars compacta (SNc) is sufficient to suppress dopamine release in the dorsal striatum. Overall, this work provides novel insight into the role of the patch compartment in habit formation, and provides a potential mechanism for how patches modify habitual behavior by exerting control over dopamine signaling.

Choice history effects in mice and humans improve reward harvesting efficiency

Choice history effects describe how future choices depend on the history of past choices. In experimental tasks this is typically framed as a bias because it often diminishes the experienced reward rates. However, in natural habitats, choices made in the past constrain choices that can be made in the future. For foraging animals, the probability of earning a reward in a given patch depends on the degree to which the animals have exploited the patch in the past. One problem with many experimental tasks that show choice history effects is that such tasks artificially decouple choice history from its consequences on reward availability over time. To circumvent this, we use a variable interval (VI) reward schedule that reinstates a more natural contingency between past choices and future reward availability. By examining the behavior of optimal agents in the VI task we discover that choice history effects observed in animals serve to maximize reward harvesting efficiency. We further distil the function of choice history effects by manipulating first- and second-order statistics of the environment. We find that choice history effects primarily reflect the growth rate of the reward probability of the unchosen option, whereas reward history effects primarily reflect environmental volatility. Based on observed choice history effects in animals, we develop a reinforcement learning model that explicitly incorporates choice history over multiple time scales into the decision process, and we assess its predictive adequacy in accounting for the associated behavior. We show that this new variant, known as the double trace model, has a higher performance in predicting choice data, and shows near optimal reward harvesting efficiency in simulated environments. These results suggests that choice history effects may be adaptive for natural contingencies between consumption and reward availability. This concept lends credence to a normative account of choice history effects that extends beyond its description as a bias.

Holocene climate and oceanography of the coastal Western United States and California Current System

To understand and contextualize modern climate change, we must improve our understanding of climatic and oceanographic changes in the Holocene (11.75 ka–present). Climate records of the Holocene can be utilized as a “baseline” from which to compare modern climate and can also provide insights into how environments and ecosystems experience and recover from environmental change. However, individual studies on Holocene climate in the literature tend to focus on a distinct geographic location, a specific proxy record, or a certain aspect of climate (e.g., upwelling or precipitation), resulting in localized, record-specific trends rather than a comprehensive view of climate variability through the Holocene. Here we synthesize the major oceanographic and terrestrial changes that have occurred in the Western United States (bounded by 30° N to 52° N and 115° W to 130° W) through the most recent 11.75 ka and explore the impacts of these changes on marine and terrestrial ecosystems and human populations. This three-tiered systematic review combines interpretations from over 100 published studies, codes and geospatially analyzes temperature, hydroclimate, and fire history from over 50 published studies, and interprets nine representative time series through the Holocene. We find that the early Holocene is characterized by warming relative to pre-Holocene conditions, including warm sea surface conditions, a warm and dry Pacific Northwest, a warm and wet Southwest, and overall spatial and temporal stability. In the mid Holocene, these patterns reverse; this interval is characterized by cool sea surface temperatures, a cool and wet Pacific Northwest and warm and dry Southwest. The late Holocene is the most variable interval, both spatially and temporally, and a novel spatial trend appears in terrestrial climate with warmer coastal areas and cooler inland areas. Human communities interacted with the environment throughout the entire Holocene, as evidenced in archeological and paleoenvironmental records, yet the recent era of colonization (1850–present) represents an unprecedented environmental interval in many records. Overall, our analysis shows linkages between terrestrial and oceanographic conditions, distinct environmental phases through time, and emphasizes the importance of local factors in controlling climate through the dynamic Holocene.

Hermite–Hadamard Inclusions for Co-Ordinated Interval-Valued Functions via Post-Quantum Calculus

In this paper, the notions of post-quantum integrals for two-variable interval-valued functions are presented. The newly described integrals are then used to prove some new Hermite–Hadamard inclusions for co-ordinated convex interval-valued functions. Many of the findings in this paper are important extensions of previous findings in the literature. Finally, we present a few examples of our new findings. Analytic inequalities of this nature and especially the techniques involved have applications in various areas in which symmetry plays a prominent role.

Behavioral effects of changeover delays in a concurrent-chains schedule with different delays and magnitudes of reinforcement

The present study examined the effects of a changeover delay (COD) on the choice between smaller, shorter delayed reinforcement and larger, longer delayed reinforcement in a complex concurrent-chains schedule. Four pigeons were exposed to three conditions in an ABA or BAB reversal design. A COD of 2 seconds was included in the initial links during condition B. The concurrent-chains schedule had identical variable-interval schedules in the initial links and different delays and magnitudes of reinforcement that were programmed according to a fixed-ratio 10 (FR10) schedule in the terminal links. Each experimental condition lasted for two long sessions and five short sessions. Changeover rates were lower, and preference for the larger, longer delayed reinforcer was more pronounced during conditions with the programmed 2-second COD. The analysis of initial pauses and running rates during the FR10 schedules of the terminal links revealed no systematic effects of the COD on behavior in the terminal links. The COD had similar effects on choice performance in this modified concurrent-chain procedure as on simple concurrent performance.Keywords: Choice behavior, concurrent-chains, COD, self-control paradigm, pigeons.