Article ID: 2208si
In this article, I outline four animal studies representing topics in physiological psychology that are selected according to my research interest: 1) timing research, 2) intracranial self-stimulation related to brain and behavior, 3) optogenetics, a new technique controlling cell function with light, and 4) social neuroscience on the relationship among multiple organisms. Then, I present miscellaneous ideas about the future direction of animal physiological psychology.