Background. Moral behavior is a fundamental issue for human societies. We often make choices on the basis of the subjective value (utility) of the available options. Examples include animal foraging and human value-based decision-making. Utility comes in two flavours. Economic utility captures the personal value consequences of one's decisions whereas moral utility captures value consequences for others. Microeconomic theories of economic utility provide formal models of how economic utility relates to the objective properties of choice options such as their reward magnitude, probability, risk and delay. Crucially, the same economic models also capture moral utility, suggesting that economic and moral utility can be calculated similarly. For example, the expected economic and moral utility of an option can be calculated with: EU=sigma(u(m)*p), where p corresponds to objective reward probability, m to objective reward magnitude, and utility u to a subjective, monotonically increasing function of m. Despite the common formalism, it is an open question whether the behavioural and neural mechanisms underlying economic and moral utility calculations are the same. I have elaborated the framework for the present project more fully elsewhere (Tobler et al., 2008). My previous work revealed neural correlates of economic utility components, particularly in the dopamine system (Tobler et al., 2005, 2007, 2009).

Individual differences in economic and moral utility processing.

Individuals differ considerably in their sensitivity to economic and moral value. Previously, I have elucidated the role of dopamine neurons in economic reward processing (e.g. Tobler et al., 2005). Dopamine neurons project strongly to the striatum and the prefrontal cortex (PFC) and these regions process economic reward parameters as well (Tobler et al., 2007, 2009). The present project therefore focuses on the genetic basis of the dopamine system. There is a number of enzymes and proteins determining the availability and action of dopamine (synthesis: tyrosine hydroxylase (TH) and DOPA decarboxylase, reuptake: dopamine transporter (DAT), pre- and postsynaptic receptors: dopamine receptors 1-5 (DRD 1-5) and metabolism: catechol-O-methyl-transferase (COMT), dopamine beta hydroxylase (DBH) and monoamine oxidase (MAO)). A variety of genes controls these proteins and enzymes (e.g. Gasso et al., 2009). Single-nucleotide polymorphisms (SNPs) in such genes may explain some of the behavioral and neural variability in dopamine function and, by extension, in economic and moral value processing. Indeed, some previous genetic studies point to a role of lateral PFC and ventral stratum dopamine function, as indexed by polymorphisms of the COMT, DAT and DRD2 genes, in modulating individual differences in economic reward processing (Yacubian et al., 2007, Schmack et al., 2008; Dreher et al, 2009; Forbes et al., 2009). The rationale for the present project is to use genetic screening to study the genetic basis of individual differences in the behavioural processing of economic and moral utility.

Hypotheses and method. Individual differences in genetic make-up will be assessed with the hypothesis that genetic differences in the dopamine system predict behavioural differences in processing of moral and economic utility. More specicifically, two sets of alternative sub-hypotheses will be tested:

1a) Behavioral indicators (see below) of economic and moral value processing increase monotonically with SNPs leading to increases in prefrontal and striatal dopamine activity and availability

1b) Behavioral indicators follow an inverted-U function of such dopamine activity and availability, in analogy to previous findings that both too little and too much dopamine can be detrimental to cognitive functions (e.g. the Avon-based study of Barnett et al., 2009)

2a) Behavioural indicators of economic and moral value are modulated by the same genes of the dopamine system

2b) Behavioural indicators of economic and moral value are modulated by different genes of the dopamine system

The method will be to ask the children to answer a short (about 20 minutes) questionnaire that reveals individual differences in the following behavioural indicators of economic and moral utility processing: a) Sensitivity to magnitude, b) Sensitivity to probability, c) Risk attitude, and d) Temporal discounting (attitude to delay). In each question, participants will make a decision between two options. The questions are ordered in a systematic way, such that answering them is quick (see examples). Questions about economic value involve monetary amounts, probabilities, risk and time while questions about moral value in addition involve a moral dimension (choices involving stolen money (see examples) and giving to charity (e.g. Moll et al., 2006)). The questionaires will in turn be longitudinally informed by the ALSPAC measures of prosocial, asocial, illegal and impulsive behaviour. IQ and 2D:4D will serve as covariates. For all types of questions on moral and economic value, individual differences in equivalence points (switching-over from low to high risk/delay) and differences of such differences (sensitivity to magnitude and probability) will be taken and related to genetic differences in the dopamine system. Under hypo-thesis 1a), sensitivity to magnitude and probability, proneness to risk and unwillingness to wait would increase with genetic variation resulting in higher dopamine activity and availability. Conversely, these variables would peak at intermediate levels of dopamine activity and availability under hypothesis 1b).