A computational and neural model of momentary subjective well-being

Abstract

The subjective well-being or happiness of individuals is an important metric for societies. Although happiness is influenced by life circumstances and population demographics such as wealth, we know little about how the cumulative influence of daily life events are aggregated into subjective feelings. Using computational modeling, we show that emotional reactivity in the form of momentary happiness in response to outcomes of a probabilistic reward task is explained not by current task earnings, but by the combined influence of recent reward expectations and prediction errors arising from those expectations. The robustness of this account was evident in a large-scale replication involving 18,420 participants. Using functional MRI, we show that the very same influences account for task-dependent striatal activity in a manner akin to the influences underpinning changes in happiness.

Keywords: dopamine; insula; reward prediction error; striatum.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Effect of previous rewards and expectations on happiness ratings. (A) Experimental design. In each trial, subjects chose between a certain option and a gamble. Chosen gambles were resolved after a 6-s-delay period. Every two to three trials, subjects were asked to indicate “How happy are you at this moment?” by using button presses to move a cursor. (B–D) Cumulative task earnings and happiness ratings across subjects (n = 26) in B and in example subjects in C and D. Happiness model fits are displayed for the model in Fig. 2A [r2 = 0.47 ± 21 (mean ± SD); example subjects r2 = 0.79 in C and r2 = 0.41 in D].

Fig. 2.

Computational model fits for three experiments. (A) The computational model that best explained happiness in the fMRI experiment (n = 26) had positive weights for previous CRs, gamble EVs, and gamble RPEs. (B) A behavioral experiment (“current earnings always shown”; n = 22) in which the current level of wealth was displayed at all times during the experiment, including during happiness ratings, replicated behavioral findings from the fMRI experiment. (C) An additional behavioral experiment (“only some gamble outcomes shown”; n = 21) similarly replicated previous findings. In this experiment, gamble choices had a 50% probability of ending with the text “outcome added to total” instead of the outcome being revealed. (D) This experimental design allowed the separation of expectation effects related to choices and outcomes. When the RPE term (reward minus EV) was split into separate GR and gamble EV terms, happiness ratings were positively correlated with GRs and negatively correlated with gamble EV at outcome.

Fig. 3.

Smartphone-based large-scale replication. (A) A screenshot from the smartphone experiment. In each trial, participants chose between a certain option and a gamble. Here the choice is between a certain 30 points and a gamble to gain 72 points or 0 points. Every two to three trials, participants were asked to indicate, “How happy are you at this moment?” (B) The computational model that best explained happiness in the first 200 participants had positive CR, gamble EV, and gamble RPE weights. Error bars represent SEM. (C) This model also explained the happiness rating after the first two to three trials from each participant, with similar model fits for a single happiness rating from each participant (n = 18,420). Error bars represent SE computed from the covariance matrix of the single model fit.

Fig. 4.

Relationship between happiness and neural responses during preceding events. (A) Striatal activity during task events preceding subjective state ratings correlated with later self-reported happiness (P < 0.05, small-volume corrected). (B) Neural responses in ventral striatum were explained by the same parametric task variables as the variables that explained happiness. Error bars represent SEM.

Fig. 5.

Effect of the happiness question on neural activity in the right anterior insula. (A) In the right anterior insula, neural activity at the time of the happiness question presentation correlated with how happy subjects reported being (P < 0.01, small-volume corrected). (B) Parameter estimates were similar for subjects with low or high life happiness. Error bars represent SEM.