The sensitivity to fairness undergoes relevant changes across development. Whether such changes depend on primary inequity aversion or on sensitivity to a social norm of fairness is still debated. Using a modified version of the Ultimatum Game that creates informational asymmetries between Proposer and Responder, a previous study showed that both perceptions of fairness and fair behavior depend upon normative expectations, i.e., beliefs about what others expect one should do in a specific situation. Individuals tend to comply with the norm when risking sanctions, but disregard the norm when violations are undetectable. Using the same methodology with children aged 8-10 years, the present study shows that children's beliefs and behaviors differ from what is observed in adults. Playing as Proposers, children show a self-serving bias only when there is a clear informational asymmetry. Playing as Responders, they show a remarkable discrepancy between their normative judgment about fair procedures (a coin toss to determine the offer) and their behavior (rejection of an unfair offer derived from the coin toss), supporting the existence of an outcome bias effect. Finally, our results reveal no influence of theory of mind on children's decision-making behavior.

We measured the beliefs and behavior of third parties who were given the opportunity to add to or deduct from the payoffs of individuals who engaged in an economic bargaining game under different social contexts. Third parties rewarded bargaining outcomes that were equal and compensated victims of unfair bargaining outcomes rather than punishing perpetrators, but were willing to punish when compensation was not an available option. Beliefs of whether unequal bargaining outcomes were fair differed based on the normative context, but actual punishment, compensation, and rewarding behavior did not. This paper makes a contribution to the literature on informal mechanisms of social norm enforcement by comparing negative sanctions, positive sanctions, and compensation behavior by third parties. (C) 2013 Elsevier B.V. All rights reserved.

Using an economic bargaining game, we tested for the existence of two phenomena related to social norms, namely norm manipulation – the selection of an interpretation of the norm that best suits an individual – and norm evasion – the deliberate, private violation of a social norm. We found that the manipulation of a norm of fairness was characterized by a self-serving bias in beliefs about what constituted normatively acceptable behavior, so that an individual who made an uneven bargaining offer genuinely believed it was fair, even though recipients of the offer considered it to be unfair. In contrast, norm evasion operated as a highly explicit process. When they could do so without the recipient’s knowledge, individuals made uneven offers despite knowing that their behavior was unfair.

CONTEXT Nonpsychotic siblings of patients with childhood-onset schizophrenia (COS) share cortical gray matter abnormalities with their probands at an early age; these normalize by the time the siblings are aged 18 years, suggesting that the gray matter abnormalities in schizophrenia could be an age-specific endophenotype. Patients with COS also show significant white matter (WM) growth deficits, which have not yet been explored in nonpsychotic siblings. OBJECTIVE To study WM growth differences in nonpsychotic siblings of patients with COS. DESIGN Longitudinal (5-year) anatomic magnetic resonance imaging study mapping WM growth using a novel tensor-based morphometry analysis. SETTING National Institutes of Health Clinical Center, Bethesda, Maryland. PARTICIPANTS Forty-nine healthy siblings of patients with COS (mean [SD] age, 16.1 [5.3] years; 19 male, 30 female) and 57 healthy persons serving as controls (age, 16.9 [5.3] years; 29 male, 28 female). INTERVENTION Magnetic resonance imaging. MAIN OUTCOME MEASURE White matter growth rates. RESULTS We compared the WM growth rates in 3 age ranges. In the youngest age group (7 to <14 years), we found a significant difference in growth rates, with siblings of patients with COS showing slower WM growth rates in the parietal lobes of the brain than age-matched healthy controls (false discovery rate, q = 0.05; critical P = .001 in the bilateral parietal WM; a post hoc analysis identified growth rate differences only on the left side, critical P = .004). A growth rate difference was not detectable at older ages. In 3-dimensional maps, growth rates in the siblings even appeared to surpass those of healthy individuals at later ages, at least locally in the brain, but this effect did not survive a multiple comparisons correction. CONCLUSIONS In this first longitudinal study of nonpsychotic siblings of patients with COS, the siblings showed early WM growth deficits, which normalized with age. As reported before for gray matter, WM growth may also be an age-specific endophenotype that shows compensatory normalization with age.

We explored regional and total volumetric cerebellar differences in probands and their unaffected full siblings relative to typically developing participants. Participants included 94 (51 males) patients diagnosed with childhood onset schizophrenia (COS), 80 related non-psychotic siblings (37 males) and 110 (64 males) typically developing participants scanned longitudinally. The sample mean age was 16.87(S.D.=4.7; range 6.5 to 29). We performed mixed model regressions to examine group differences in trajectory and volume. The COS group had smaller bilateral anterior lobes and anterior and total vermis volumes than controls. The COS group diverged from controls over time in total, left, right, and bilateral posterior inferior cerebellum. Siblings did not have any fixed volumetric differences relative to controls but differed from controls in developmental trajectories of total and right cerebellum, left inferior posterior, left superior posterior, and superior vermis. Results are consistent with previous COS findings and several reports of decreased cerebellar volume in adult onset schizophrenia. Sibling trajectories may represent a trait marker, although the effect size for volumetric differences in early adulthood may be small.

Background: Little is known about the effects of antipsychotic medications on gray matter (GM) in schizophrenia. Although clozapine remains the most effective antipsychotic medication in treatment-refractory cases, it is unknown whether it has a differential effect on GM development.Methods: In an exploratory analysis, we used automated cortical thickness measurements and prospectively scanned childhood-onset schizophrenia (COS) patients who were maintained on one medication. Two atypical antipsychotic medications, clozapine (n=12, 37 scans) and olanzapine (n=12, 33 scans) were compared with respect to effects on cortical development, in contrast to GM trajectories of matched controls.Results: There were no significant differences in the trajectories of cortical thickness between the two treatment groups with the exception of a small circumscribed area in the right prefrontal cortex, where the olanzapine group showed thicker cortex As expected, both groups showed thinner GM compared to matched controls.Conclusions: Although these analyses do not rule out effects of antipsychotic medications on GM development in schizophrenia, they show no differential effect between clozapine and olanzapine on GM trajectory. Published by Elsevier B.V.

We study the behavioral consequences of interpersonal communication prior to experimental Trust games. We manipulated the richness of the communication medium and the size of the communicating group. Communication richness failed to produce significant differences in first-mover investments, but the size of the communicating group did: The amounts sent were significantly higher in the dyadic communication conditions than in the group communication and no-communication conditions. We also found that first-movers’ expectations of secondmovers’ reciprocation strongly predicted their levels of investment.

What is considered to be fair depends on context. Using a modified version of the Ultimatum Game, we demonstrate that both fair behavior and perceptions of fairness depend upon beliefs about what one ought to do in a situation - that is, upon normative expectations. We manipulate such expectations by creating informational asymmetries about the offer choices available to the Proposer, and find that behavior varies accordingly. Proposers and Responders show a remarkable degree of agreement in their beliefs about which choices are considered fair. We discuss how these results fit into a theory of social norms. Published version: Bicchieri, C. & Chavez, A. (2010) Behaving as Expected: Public information and fairness norms. Journal of Behavioral Decision Making, 23(2), 161-178.

Subjects communicated prior to playing trust games; the richness of the communication media and the topics of conversation were manipulated. Communication richness failed to produce significant differences in first-mover investments. However, the topics of conversation made a significant difference: The amounts sent were considerably higher in the unrestricted communication conditions than in the restricted communication and no-communication conditions. Most importantly, we find that first-movers’ expectations of second-movers’ reciprocation are influenced by communication and strongly predict their levels of investment.

Objective To highlight emerging evidence for clinical and biological links between autism/pervasive developmental disorder (PDD) and schizophrenia, with particular attention to childhood-onset schizophrenia (COS). Method Clinical, demographic, and brain developmental data from the National Institute of Mental Health (and other) COS studies and selected family, imaging, and genetic data from studies of autism, PDD, and schizophrenia were reviewed. Results In the two large studies that have examined this systematically, COS is preceded by and comorbid with PDD in 30% to 50% of cases. Epidemiological and family studies find association between the disorders. Both disorders have evidence of accelerated trajectories of anatomic brain development at ages near disorder onset. A growing number of risk genes and/or rare small chromosomal variants (microdeletions or duplications) are shared by schizophrenia and autism. Conclusions Biological risk does not closely follow DSM phenotypes, and core neurobiological processes are likely common for subsets of these two heterogeneous clinical groups. Long-term prospective follow-up of autistic populations and greater diagnostic distinction between schizophrenia spectrum and autism spectrum disorders in adult relatives are needed.

Metagames (Howard, 1968), a class of formal models in game theory, model the behavior of players who predict each other's conditional strategies recursively. We present a framework for three-player games based on metagame theory. This framework is well-suited to the analysis of nation-states, especially when the analyst wishes to make few assumptions about the level of recursive reasoning and the preference orderings of players.

Earlier studies revealed progressive cortical gray matter (GM) loss in childhood-onset schizophrenia (COS) across both lateral and medial surfaces of the developing brain. Here, we use tensor-based morphometry to visualize white matter (WM) growth abnormalities in COS throughout the brain. Using high-dimensional elastic image registration, we compared 3D maps of local WM growth rates in COS patients and healthy children over a 5-year period, based on analyzing longitudinal brain MRIs from 12 COS patients and 12 healthy controls matched for age, gender, and scan interval. COS patients showed up to 2.2% slower growth rates per year than healthy controls in WM ( P = 0.02, all P values corrected). The greatest differences were in the right hemisphere ( P = 0.006). This asymmetry was attributable to a right slower than left hemisphere growth rate mapped in COS patients ( P = 0.037) but not in healthy controls. WM growth rates reached 2.6% per year in healthy controls ( P = 0.0002). COS patients showed only a 1.3% per year trend for growth in the left hemisphere ( P = 0.066). In COS, WM growth rates were associated with improvement in the Children's Global Assessment Scale ( R = 0.64, P = 0.029). Growth rates were reduced throughout the brain in COS, but this process appeared to progress in a front-to-back (frontal-parietal) fashion, and this effect was not attributable to lower IQ. Growth rates were correlated with functional prognosis and were visualized as detailed 3D maps. Finally, these findings also confirm that the progressive GM deficits seen in schizophrenia are not the result of WM overgrowth.