Esther Herrmann, Lou M. Haux, Henriette Zeidler and Jan M. Engelmann January 2019 https://doi.org/10.1098/rspb.2018.2228
The paper asks if Social Comparison can motivate primates to make stupid value-based choices. (see Test condition below).
Three things are particularly cool about the paper: (1) Authors set social comparative and absolute personal gain against each other very nicely; (2) They compare chimps, young (5-6yr) and older (9-10yr) children; (3) Very careful controls are used.
Results are amazing (see Figure below). Young children and chimps prefer the option that benefits themselves most (right-side tray in the figure above). Older children are much more likely to choose the option that gives them a social comparative advantage (left tray). They are indifferent (50-50) when choosing between the two trays.
Their controls show that all three groups are capable of making the obvious choice if it does not involve social comparison. Plus, they also show that older children are not seeking fairness (i.e., equal pay through mixing two types of reward).
It is a great paper !