Eldar, Eran, Genela Morris, and Yael Niv. 2011. “The Effects of Motivation on Response Rate: A Hidden Semi-Markov Model Analysis of Behavioral Dynamics”. Journal of Neuroscience Methods 201 (1): 251–261. doi:10.1016/j.jneumeth.2011.06.028.

Niv, Yael, Nathaniel Daw, Daphna Joel, and Peter Dayan. 2007. “Tonic Dopamine: Opportunity Costs and the Control of Response Vigor”. Psychopharmacology 191 (3): 507–520. doi:10.1007/s00213-006-0502-4.