Search

We examine a common value dynamic matching environment where adverse selection accrues slowly over time. Theoretical best responses are therefore time varying, and the prior experimental literature suggests that sequential environments might lead to greater understanding of adverse selection in this dynamic setting. However, while a sophisticated minority in our experiment do condition on time and are close to a best response, the majority use a stationary response, even after extended experience. In an environment with persistent uncertainty, our results indicate that sequentiality is insufficient for the large majority of participants to recognize the effects of adverse selection. (JEL C78, C92, D82, D91)

This paper presents a two-wave survey experiment on self-image concerns in moral voting. We elicit votes on the so-called Horncow Initiative. This initiative required subsidization of farmers who refrain from dehorning. We investigate how non-consequentialist and non-deontological messages changing the moral self-signaling value of a Yes vote affect selection and processing of consequentialist information, and reported voting behavior. We find that a message enhancing the self-signaling value of a Yes vote is effective: voters agree more with arguments in favor of the initiative, anticipate more frequently voting in favor, and report more frequently having voted in favor of the initiative.

Standardized classroom experiments provide evidence about how well scientific results reproduce when nearly identical methods are used. We use a sample of around 20,000 observations to test reproducibility of behaviour in trading and ultimatum bargaining. Double-auction results are highly reproducible and are close to equilibrium predictions about prices and quantities from economic theory. Our sample also shows robust correlations between individual surplus and trading order, and autocorrelation of successive price changes, which test different theories of price dynamics. In ultimatum bargaining, the large dataset provides sufficient power to identify that equal-split offers are accepted more often and more quickly than slightly unequal offers. Our results imply a general consistency of results across a variety of different countries and cultures in two of the most commonly used designs in experimental economics.

Microtubules (MTs) mediate mitosis, directional signaling, and are therapeutic targets in cancer. Yet in vivo analysis of cancer cell MT behavior within the tumor microenvironment remains challenging. Here we developed an imaging pipeline using plus-end tip tracking and intravital microscopy to quantify MT dynamics in live xenograft tumor models. Among analyzed features, cancer cells in vivo displayed higher coherent orientation of MT dynamics along their cell major axes compared with 2D in vitro cultures, and distinct from 3D collagen gel cultures. This in vivo MT phenotype was reproduced in vitro when cells were co-cultured with IL4-polarized MΦ. MΦ depletion, MT disruption, targeted kinase inhibition, and altered MΦ polarization via IL10R blockade all reduced MT coherence and/or tumor cell elongation. We show that MT coherence is a defining feature for in vivo tumor cell dynamics and migration, modulated by local signaling from pro-tumor macrophages., The regulation of microtubule (MT) dynamics in cancer cells within the tumor microenvironment is less understood. Here, the authors develop an imaging platform to examine MT dynamics in live xenograft models and show that pro-tumor macrophages modulate MT coherence and alignment to promote cancer cell migration.

Real-effort experiments are frequently used when examining a response to incentives. For a real-effort task to be well suited for such an exercise its measurable output must be sufficiently elastic over the incentives considered. The popular slider task in Gill and Prowse (Am Econ Rev 102(1):469–503, 2012) has been characterized as satisfying this requirement, and the task is increasingly used to investigate the response to incentives. However, a between-subject examination of the slider task’s response to incentives has not been conducted. We provide such an examination with three different piece-rate incentives: half a cent, two cents, and eight cents per slider completed. We find only a small increase in performance: despite a 1500 % increase in the incentives, output only increases by 5 %. With such an inelastic response we caution that for typical experimental sample sizes and incentives the slider task is unlikely to demonstrate a meaningful and statistically significant performance response.

We study the effect of financial resources on decision-making. Low-income US households are randomly assigned to receive an online survey before or after payday. The survey collects measures of cognitive function and administers risk and intertemporal choice tasks. The study design generates variation in cash, checking and savings balances, and expenditures. Before-payday participants behave as if they are more present-biased when making intertemporal choices about monetary rewards but not when making intertemporal choices about nonmonetary real-effort tasks. Nor do we find before-after differences in risk-taking, the quality of decision-making, the performance in cognitive function tasks, or in heuristic judgments. (JEL C83, D14, D81, D91, I32)

We introduce, test, and compare two auction-based methods for eliciting discount rates. In these “patience auctions”, participants bid the smallest future sum they would prefer -or- the longest time they would wait for a reward, rather than receive a smaller, immediate payoff. The most patient bidder receives the delayed reward; all others receive the immediate payoff. These auctions allow us to compare discounting when participants’ attention is focused on the temporal versus monetary dimension of delayed rewards. We find that the estimated parameters in the three most commonly used discount functions (exponential, hyperbolic, and quasi-hyperbolic) differ across these two bidding methods (time-bids vs. money-bids). Specifically, our participants tend to show more impatience under time-bids. Furthermore, we find that people are more likely to exhibit exponential (as opposed to hyperbolic) discounting and exhibit less present bias under time-bids, compared to money-bids. To our knowledge, this paper is the first to directly compare time versus money preference elicitations, within the same subjects, using an incentive-compatible mechanism.

We introduce DOSE - Dynamically Optimized Sequential Experimentation - and use it to estimate individual-level loss aversion in a representative sample of the U.S. population (N = 2;000). DOSE elicitations are more accurate, more stable across time, and faster to administer than standard methods. We find that around 50% of the U.S. population is loss tolerant. This is counter to earlier findings, which mostly come from lab/student samples, that a strong majority of participants are loss averse. Loss attitudes are correlated with cognitive ability: loss aversion is more prevalent in people with high cognitive ability, and loss tolerance is more common in those with low cognitive ability. We also use DOSE to document facts about risk and time preferences, indicating a high potential for DOSE in future research.

Adaptive signaling through receptor tyrosine kinases (RTKs) has been highly implicated in the resistance to drugs targeting constitutive RAS/RAF/MEK/ERK signaling, particularly in malignancies with constitutive V600 BRAF mutation. However, it has been difficult to systematically understand how such RTK-mediated bypass signaling is influenced by dynamic and localized interactions between tumor cells and neighboring stromal and immune populations. Here we present a pipeline that combines single-cell and bulk transcriptomic analysis from patients, with systems-level mapping of phosphosignaling pathways in co-cultures, to guide the longitudinal in vivo confocal (intravital) microscopy of adaptive bypass signaling in mouse models of BRAF-mutant cancer. This pipeline prioritizes key myeloid populations and phosphosignaling activities (including of ERK) to image in vivo. Intravital microscopy reveals how therapy-induced myeloid accumulation simultaneously shapes the local activity of multiple co-regulated signaling pathways in neighboring cancer cells, in a RTK-dependent manner. Overall, this work offers an integrative approach to quantitating multiple single-cell signaling pathway activities in the tumor microenvironment, and directly images the dynamics with which known cancer-cell autonomous mechanisms of targeted therapy resistance can be locally amplified by neighboring immune cell populations. Citation Format: Stephanie Wang, Ralph Weissleder, Douglas Lauffenburger, Miles Miller. Molecular systems-guided imaging of multicellular in situ adaptation to targeted therapy in BRAF-mutant cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-A03. doi:10.1158/1535-7163.TARG-19-LB-A03

Standardized classroom economics experiments provide a treasure trove of evidence about how well results reproduce when nearly-identical methods are used. We use a sample of around 20,000 observations to test reproducibility in bargaining and trading. Ultimatum bargaining exhibits some geographical variation, and shows that equal split offers are accepted more often and more quickly than slightly unequal offers. Double auction results are highly reproducible and are close to equilibrium predictions. Our large sample shows robust, strong correlations between how individual surplus and trading order, and autocorrelation ( 0.5) of successive price changes, consistent with trading dynamics based on limited rationality.

To understand the thinking process in private information games, we use “Mousetracking” to record which payoffs subjects attend to. The games have three information states and vary in strategic complexity. Subjects consistently deviate from Nash equilibrium choices and often fail to look at payoffs which they need to in order to compute an equilibrium response. Choices and lookups are similar when stakes are higher. When cluster analysis is used to group subjects according to lookup patterns and choices, three clusters appear to correspond approximately to level-3, level-2, and level-1 thinking in level-k models, and a fourth cluster is consistent with inferential mistakes (as, for example, in QRE or Cursed Equilibrium theories). Deviations from Nash play are associated with failure to look at the necessary payoffs. The time durations of looking at key payoffs can predict choices, to some extent, at the individual level and at the trial-by-trial level.

The microRNA miR-150, a critical regulator of hematopoiesis, is downregulated in mixed-lineage leukemia (MLL). In this study, miR-150 acts as a potent leukemic tumor suppressor by blocking the oncogenic properties of leukemic cells. By using MLL-AF9–transformed cells, we demonstrate that ectopic expression of miR-150 inhibits blast colony formation, cell growth, and increases apoptosis in vitro. More importantly, ectopic expression of miR-150 in MLL-AF9–transformed cells completely blocked the development of myeloid leukemia in transplanted mice. Furthermore, gene expression profiling revealed that miR-150 altered the expression levels of more than 30 “stem cell signature” genes and many others that are involved in critical cancer pathways. In addition to the known miR-150 target Myb, we also identified Cbl and Egr2 as bona fide targets and shRNA-mediated suppression of these genes recapitulated the pro-apoptotic effects observed in leukemic cells with miR-150 ectopic expression. In conclusion, we demonstrate that miR-150 is a potent leukemic tumor suppressor that regulates multiple oncogenes. Implications: These data establish new, key players for the development of therapeutic strategies to treat MLL-AF9–related leukemia. Mol Cancer Res; 11(8); 912–22. ©2013 AACR.

Non-incentivized belief elicitation has a negative effect on the belief accuracy of experienced observers predicting choices in 2 × 2 matrix games. This negative impact extends to the accuracy of group beliefs and revised beliefs after forecasters know each other's initial beliefs.

Objective: To test the hypothesis that economic recessions lead to reduced global development assistance for health (DAH). Methods: Data obtained from the Creditor Reporting System of the Organisation for Economic Co-operation and Development (OECD) for 15 OECD countries were used to model the percentage change (relative difference) in commitments and disbursements for DAH as a function of three measures of economic recession: recessionary year (as a dummy variable with 0 for no recession and 1 for recession), percentage change in per capita gross domestic product and percentage point change in unemployment rate for recessionary cycles from 1975 through 2007. We looked for an association both during the concurrent recessionary year and one and two years later. Findings: No statistically significant association was found in the short or long run between measures of economic recession and the amount of official DAH committed or disbursed. Conclusion: Any important decrease in overall DAH following the current economic recession would have little historical precedent and claims of inevitability would be unjustifiable.

In visual search tasks, if a set of items is presented fo r 1 s before another set of new items (containing the target) is added, search can be restricted to the new set. The process that eliminates old items from search is visual marking. This study investigates the kind of memory that distinguishes the old items from the new items during search. Using an accuracy paradigm in which perfect marking results in 100% accuracy and lack of marking results in near chance performance, the authors show that search can be restricted to new items not by visual short-term memory (VSTM) of old locations but by a limited capacity and slow-decaying VSTM of new locations and a high capacity and fast-decaying memory for asynchrony.

Hindsight bias is the tendency to retrospectively think of outcomes as being more foreseeable than they actually were. It is a robust judgment bias and is difficult to correct (or “debias”). In the experiments reported here, we used a visual paradigm in which performers decided whether blurred photos contained humans. Evaluators, who saw the photos unblurred and thus knew whether a human was present, estimated the proportion of participants who guessed whether a human was present. The evaluators exhibited visual hindsight bias in a way that matched earlier data from judgments of historical events surprisingly closely. Using eye tracking, we showed that a higher correlation between the gaze patterns of performers and evaluators (shared attention) is associated with lower hindsight bias. This association was validated by a causal method for debiasing: Showing the gaze patterns of the performers to the evaluators as they viewed the stimuli reduced the extent of hindsight bias.

In this paper, we derive and experimentally test a theoretical model of speculation in multiperiod asset markets with public information flows. The speculation arises from the traders' heterogeneous posteriors as they make different inferences from sequences of public information. This leads to overpricing in the sense that price exceeds the most optimistic belief about the real value of the asset. We find evidence of speculative overpricing in both incomplete and complete markets, where the information flow is a gradually revealed sequence of imperfect public signals about the state of the world. We also find evidence of asymmetric price reaction to good news and bad news, another feature of equilibrium price dynamics under our model. Markets with a relaxed short-sale constraint exhibit less overpricing.

Behavior in two-player laboratory games has been observed to depend upon choices that the other player "could have made," in violation of the principle of subgame perfection. Models of other-regarding preferences that only transform payoffs at end-nodes (e.g. inequality aversion) cannot explain this behavior, and various explanations (e.g. models of intention-based reciprocity) have been proposed. We explore the mechanisms by which foregone payoffs influence decision-making in a variety of two-player, two-stage games using mousetracking, a technology that allows us to observe which payoffs subjects attend to, and for how long, when making strategic decisions.

Several recent studies in experimental economics have tried to measure beliefs of subjects engaged in strategic games with other subjects. Using data from one such study we conduct an experiment where our experienced subjects observe early rounds of strategy choices from that study and are given monetary incentives to report forecasts of choices in later rounds. We elicit beliefs using three different scoring rules: linear, logarithmic, and quadratic. We compare forecasts across the scoring rules and compare the forecasts of our trained observers to forecasts of the actual players in the original experiment. We find significant differences across scoring rules. The improper linear scoring rule produces forecasts closer to 0 and 1 than the proper rules, and these forecasts are poorly calibrated. The two proper scoring rules induce significantly different distributions of forecasts. We find that forecasts by observers under both proper scoring rules are significantly different from the forecasts of the actual players, in terms of accuracy, calibration, and the distribution of forecasts. We also find evidence for belief convergence among the observers.

In experiments, people do not always appear to think very strategically or to infer the information of others from their choices. We report experimental results in games of private information with three information states, which vary in strategic complexity. \Mousetracking" is used to record which game payos subjects look at, for how long, to learn more about the thinking process. Subjects often deviate from Nash equilibrium choices, converge only modestly toward equilibrium across 40 trials, and often fail to look at payos which they need to in order to compute an equilibrium response. Theories

MicroRNAs (miRNAs) are a family of ≈22-nt noncoding RNAs that can posttranscriptionally regulate gene expression. Several miRNAs are specifically expressed in hematopoietic cells. Here we show that one such miRNA, miR-150, is mainly expressed in the lymph nodes and spleen and is highly up-regulated during the development of mature T and B cells; expression of miR-150 is sharply up-regulated at the immature B cell stage. Overexpression of miR-150 in hematopoietic stem cells, followed by bone marrow transplantation, had little effect on the formation of either mature CD8- and CD4-positive T cells or granulocytes or macrophages, but the formation of mature B cells was greatly impaired. Furthermore, premature expression of miR-150 blocked the transition from the pro-B to the pre-B stage. Our results indicate that miR-150 most likely down-regulates mRNAs that are important for pre- and pro-B cell formation or function, and its ectopic expression in these cells blocks further development of B cells.

Leukemic stem cells (LSCs) are derived from hematopoietic stem or progenitor cells and often share gene expression patterns and specific pathways. Characterization and mechanistic studies of LSCs are critical as they are responsible for the initiation and potential relapse of leukemias, however the overall framework, including epigenetic regulation, is not yet clear. We previously identified microRNA-150 (miR-150) as a critical regulator of mixed lineage leukemia (MLL) -associated leukemias by targeting oncogenes. Our additional results suggest that miR-150 can inhibit LSC survival and disease initiating capacity by suppressing more than 30% of “stem cell signature genes,” hence altering multiple cancer pathways and/or stem cell identities. MLL-AF9 cells derived from miR-150 deficient hematopoietic stem/progenitor cells displayed significant proliferating advantage and enhanced leukemic colony formation. Whereas, with ectopic miR-150 expression, the MLL-AF9 associated LSC population (defined as Lin-ckit+sca1- cells) was significantly decreased in culture. This is further confirmed by decreased blast leukemic colony formation in vitro. Furthermore, restoration of miR-150 levels in transformed MLL-AF9 cells, which often display loss of miR-150 expression in AML patients with MLL-fusion protein expressing, completely blocked the myeloid leukemia development in a transplantation mouse model. Gene profiling analysis demonstrated that an increased level of miR-150 expression down regulates 30 of 114 stem cell signature genes by more than 1.5 fold, partially mediated by the suppressive effects of miR-150 on CBL, c-Myb and Egr2 oncogenes. In conclusion, our results suggest that miR-150 is a potent MLL-AF9 leukemic inhibitor that may act by suppressing the survival and leukemic initiating potency of MLL-AF9 LSCs. Disclosures: No relevant conflicts of interest to declare.