Figure 2.

Behavioral results. A, The subjective costs of options presented on isolated effort trials increased as a function of effort (p < 0.001), with participants judging the 100% effort option to be significantly more costly than all others (p < 0.01). B, A similar result was found for postexperiment pleasantness ratings of the effortful stimuli. C, On average, participants were risk averse, with the subjective cost of the risky options increasing as a function of the variance of the proposed lottery (p < 0.0001). D, This result was also reflected in decreasing postexperiment pleasantness ratings of the risky stimuli as a function of risk. E, Surface plot of the subjective costs of compound options. Compound options contained both effortful and risky elements, and the subjective costs associated with each option increased as a function of the additive objective levels of risk and effort (p < 0.01). F, Using participants' subjective costs on isolated effort and isolated risk trials, we could significantly predict the subjective costs on compound trials (p < 0.001). All error bars represent the standard error of the mean.