Cognition and valence as chicken and egg: Motivational force evolved alongside cognition

The convergent evolution described for invertebrate cognition might have occurred in similar fashion with motivational valence, the other pillar of response selection. Primitive examples of such properties as liking (versus wanting), dependence on appetite, and especially attenuation with delay might provide clues to a longstanding puzzle: how incentive salience, classical conditioning, emotional arousal, and mental behavior in general are apparently all entwined with valence.