A Point of View

For many years I had the distorted idea that a large back yard was a luxury to be desired since ours was comparatively small. I had gazed with envy at spacious, green lawns, edged with even, neatly trimmed hedges, with perhaps a row of rustling popular trees at one end, and carefully tended rock gardens at the other, rendering it a scene of symetry and color; yards with rose-covered trellises or graceful bird baths

Single-cell gene expression profiles define self-renewing, pluripotent, and lineage primed States of human pluripotent stem cells

Pluripotent stem cells display significant heterogeneity in gene expression, but whether this diversity is an inherent feature of the pluripotent state remains unknown. Single-cell gene expression analysis in cell subsets defined by surface antigen expression revealed that human embryonic stem cell cultures exist as a continuum of cell states, even under defined conditions that drive self-renewal. The majority of the population expressed canonical pluripotency transcription factors and could differentiate into derivatives of all three germ layers. A minority subpopulation of cells displayed high self-renewal capacity, consistently high transcripts for all pluripotency-related genes studied, and no lineage priming. This subpopulation was characterized by its expression of a particular set of intercellular signaling molecules whose genes shared common regulatory features. Our data support a model of an inherently metastable self-renewing population that gives rise to a continuum of intermediate pluripotent states, which ultimately become primed for lineage specification

Envy Freeness in Experimental Fair Division Problems

In the recent experimental literature several social preference models have been suggested that address observed behavior not reducible to the pursuit of self-interest. Inequality aversion is one such model where preferences are distributional. Frequently, envy is suggested as the underlying rationale for inequality aversion. Envy is a central criterion in the theoretical literature on fair division, whose definition (Foley 1967) differs from the more casual use of the word in the experimental literature. We present and discuss results from free-form bargaining experiments on fair division problems where the role of envy in Foley’s sense can be analyzed and compared to social preferences. We find that envy freeness does matter as a secondary criterion.Fairness, Envy Freeness, Social Preferences, Bargaining

Economic Games Quantify Diminished Sense of Guilt in Patients with Damage to the Prefrontal Cortex

Damage to the ventromedial prefrontal cortex (VMPFC) impairs concern for other people, as reflected in the dysfunctional real-life social behavior of patients with such damage, as well as their abnormal performances on tasks ranging from moral judgment to economic games. Despite these convergent data, we lack a formal model of how, and to what degree, VMPFC lesions affect an individual's social decision-making. Here we provide a quantification of these effects using a formal economic model of choice that incorporates terms for the disutility of unequal payoffs, with parameters that index behaviors normally evoked by guilt and envy. Six patients with focal VMPFC lesions participated in a battery of economic games that measured concern about payoffs to themselves and to others: dictator, ultimatum, and trust games. We analyzed each task individually, but also derived estimates of the guilt and envy parameters from aggregate behavior across all of the tasks. Compared with control subjects, the patients donated significantly less and were less trustworthy, and overall our model found a significant insensitivity to guilt. Despite these abnormalities, the patients had normal expectations about what other people would do, and they also did not simply generate behavior that was more noisy. Instead, the findings argue for a specific insensitivity to guilt, an abnormality that we suggest characterizes a key contribution made by the VMPFC to social behavior