Inoue et al. (2015)

Inoue, Y.(井上裕珠), Hoogland, C. E., Takehashi, H.(竹橋洋毅) & Murata, K.(村田光二) (2015). 
Effects of resource divisibility and expectations of sharing on envy. 
Motivation and Emotion, 1-12.
doi: 10.1007/s11031-015-9498-6
In three experiments, we provide evidence that resource divisibility and expectations of sharing influence the degree to which envy arises in response to another’s superior resources. We manipulated the resource divisibility (e.g., 2 coins worth approximately $5.50 each vs. a single note worth approximately $11) and expectations of sharing were measured (Experiments 1 and 2) and manipulated (Experiment 3). Findings in these three experiments supported our hypothesis that envy would be most strongly experienced in response to others who had highly divisible resources that participants did not believe would be shared. These findings offer novel insights into the adaptive function of envy, which may promote sharing of divisible resources.