By Emma Young
You scrape off the panels on a lottery scratch card… and you’re a winner! Brain imaging would show a burst of activity in a region called the nucleus accumbens, in the ventral striatum, a region known to code the impact of reward-related stimuli, such as getting money. But how the brain handles so-called vicarious joy — the type you might feel if you scraped winning panels from a relative’s scratch card, or even a stranger’s — is not well understood. Now a new study, published in Cognitive, Affective & Behavioural Neuroscience, shows that while there are similarities, there are also some important differences. Notably, the participants’ brains responded differently when they won money for their mother versus their father.
Philip Bradner at Erasmus University in the Netherlands led the study of 30 mostly undergraduate students, with an average age of 22. They all had a mother and a father as their parents, and none had a history of mental health issues. (In fact, they were deliberately chosen to be similar, to make for a more homogenous sample.)
While in an fMRI scanner, the participants played a simple game in which they, or one other person, could win money. In each trial, this other “player” was identified as either their mother, father, or simply as a “stranger”. All the participants had to do was click a button to choose which of two animated curtains to open. This revealed a small win for themselves and/or the other person. (And any money won for themselves or their mother or father was passed on.) After this, the participants rated how emotionally close they felt to their mother, father and to strangers, in general. They also reported on how much they liked winning for themselves, or for each parent or a stranger.
As expected from earlier research, when a participant won money for themselves, Bradner and his colleagues saw increased activity in the nucleus accumbens. But they also discovered greater activation in the nucleus accumbens when the participants won money for their mother or father, compared to when they won money for a stranger. The participants also reported “liking” winning for both parents more than for a stranger. This suggests that the nucleus accumbens is involved in feeling both direct, personal joy and also vicarious joy.
However, the participants’ brain responses also showed some differences depending on whether the other player was identified as their father or mother. When they won money for their father (but not their mother), other regions of the brain, including the medial prefrontal cortex and the precuneus, became more active.
These regions seem, then, to be important for processing vicarious joy for fathers. They are also known to be important for representing “self” vs “other” — for distinguishing between what we are experiencing directly, versus what someone else is experiencing, for example. It’s possible, then, that winning for fathers triggers stronger self/other comparisons than winning for mothers, the team writes. For these young people, at least, it seems that their mother was more integrated with their “self” representation.
This theory was supported by the additional finding that when participants won money for themselves and their father won nothing, there was less activation in the nucleus accumbens compared with when they won money and their mother didn’t. If winning against a father triggers greater self/other comparisons, then participants may process this win as a gain only for themselves, and as a relative “loss” for their father — but when the mother is the other player, winning might be a more straightforward, unmitigated joy.
The study does have various limitations. For one, because the participants were deliberately chosen to be similar, it’s not clear whether the results would hold for other groups of people, such as those with same-sex parents or from single parent households. It would also be interesting to explores effects in children of less well-adjusted families, who may feel less close to their parents, and may not experience vicarious joy in the same way. But the finding of differences in how the participants’ brains responded to rewards for fathers versus mothers is certainly interesting. If it isn’t driven by differences in emotional closeness, which it doesn’t seem to be, what, exactly, does drive it? Only further research will tell. As the team concludes, “An intriguing question for future research concerns the divergence in neural processing between mothers and fathers.”