It is a widespread notion in psychology that there are two dimensions to emotion: valence (aversiveness or attractiveness of some entity) and intensity. However, recent experimental studies in neuropsychology (e.g. those listed below) have given strong evidence for two distinct pathways which process reward and punishment associated with some input. This in turn compellingly suggests that valence is in fact made up of two independent dimensions, and I'm guessing there are behavioral studies reaching similar conclusions (i.e. that persons are able to have "mixed feelings"). How do we reconcile these views? Are we forced to reject one-dimensional valence on the basis of the evidence?
Distinct pathways for reward/punishment:
Paton, Joseph J., and Kenway Louie. "Reward and punishment illuminated." Nature neuroscience 15.6 (2012): 807. (http://www.researchgate.net/publication/225043743_Reward_and_punishment_illuminated/file/e0b495227b6d325c3d.pdf)
Fujiwara, Juri, et al. "Segregated and integrated coding of reward and punishment in the cingulate cortex." Journal of Neurophysiology 101.6 (2009): 3284-3293.
Monosov, Ilya E., and Okihide Hikosaka. "Regionally distinct processing of rewards and punishments by the primate ventromedial prefrontal cortex." The Journal of Neuroscience 32.30 (2012): 10318-10330.