We argue that the phases identified in the novelty-seeking model can be clarified by considering an updated version of the optimal-level of arousal model, which incorporates the “arousal” and “mood changing” potentials of stimuli and contexts. Such a model provides valuable insights into what determines one's state of mind, inter-individual differences, and the rewarding effects of curiosity and creativity.

Wilson et al. draw our attention to the problem of a science of intentional change. We stress the connection between their approach and existing paradigms for learning and goal generation that have been developed in machine learning, artificial intelligence, and psychology. These paradigms outline the structural principles of a domain-general and teleologically open agent.

The goal of forming a science of intentional behavior requires a more richly detailed account of symbolic systems than is assumed by the authors. Cultural systems are not simply the equivalent in the ideational domain of culture of the purported Baldwin Effect in the genetic domain. © 2014 Cambridge University Press.