Unknown to most Western psychologists, ancient Indian scriptures contain very rich, empirically derived psychological theories that are, however, intertwined with religious and philosophical content. This article represents our attempt to extract the psychological theory of cognition and consciousness from a prominent ancient Indian thought system: Samkhya-Yoga. We derive rather broad hypotheses from this approach that may complement and extend Western mainstream theorizing. These hypotheses address an ancient personality theory, the effects of practicing the applied part of Samkhya-Yoga on normal and extraordinary cognition, as well as different ways of perceiving reality. We summarize empirical evidence collected (mostly without reference to the Indian thought system) in diverse fields of research that allows for making judgments about the hypotheses, and suggest more specific hypotheses to be examined in future research. We conclude that the existing evidence for the (broad) hypotheses is substantial but that there are still considerable gaps in theory and research to be filled. Theories of cognition contained in the ancient Indian systems have the potential to modify and complement existing Western mainstream accounts of cognition. In particular, they might serve as a basis for arriving at more comprehensive theories for several research areas that, so far, lack strong theoretical grounding, such as meditation research or research on aspects of consciousness.

Ancient Indian spiritual and philosophical approaches contain psychological theories of meditation that specify (a) what meditation is, (b) what its aim is and how it works, and (c) predictions about its effects. This chapter introduces two representative theories that date back more than two millennia, one derived from early Buddhism and the other from the classical Hindu thought systems of Sāṃkhya and Yoga. According to both theories, meditation is not a single technique but a partly differing collection of many different ones. The final aim of meditation, embedded in a spiritual and moral context, is achieving a state of liberation or enlightenment, although it is unclear whether both theories refer to a common state. Both theories also predict that positive effects can already be expected for practitioners still on the way. The cognitive mechanisms that are the basis for these results are clearly described in the two respective psychological models. The two theories allow for deriving predictions that go beyond the research questions currently pursued in Western meditation research, and they can act as building blocks for a comprehensive theory of meditation.