http://www.jneurosci.org/content/jneuro/29/46/14617.full.pdf (Publisher version)
Talmi, D., Dayan, P., Kiebel, S., Frith, C., & Dolan, R. (2009). How humans integrate the prospects of pain and reward during choice. The Journal of Neuroscience, 29(46), 14617-14626. doi:10.1523/JNEUROSCI.2026-09.2009.