Consciousness is not well defined as a single, universally agreed-upon formula -- There are over 40[1] different definitions for this one word. However, there is considerable convergence of academic understanding of the term as it relates to the question most analysts would like to see answered: how are we to understand the brain's elctrochemical activity and self-reflective cognitive experience as being related? In other words, how does the brain turn material processes into the thoughts, feelings, and technicolor panorama that characterizes conscious experience? In this question (technically refered to as "The Hard Problem of Consciousness"), consciousness is understood (defined) as not merely a self-reflective state of cognition, but as cognitive content (perceptions, feelings, thoughts) self-reflectively experienced. One of the problems that has added to the confusion associated with this concept, is the idea that somehow there needed to be a 1 to 1 match between the electrochemical activity of the brain, and the self-reflective experiences. Recent conceptions have relaxed from this position suggesting that self-relfective experience is not a good indicator of brain function because it is prone to some illusions that make it subjective.
Up until 1990 when John Searle, an influential American philosopher, finally agreed that as long as testing was done in the 3rd person, objective science could be done on consciousness, research on consciousness was actively discouraged. Since that time, a broad spectrum of theories has been proposed to account for self-reflective cognition. Following the nineteenth century phenomenologists, some have suggested that mental representation as such is inherently self-cognizant and thereby underwrites consciousness [2]. However, in order to account for the fact that much if not most cognition is not conscious, most theories nominate a specific process that operates upon representational cognition to render it conscious. Such theories include the linguistic coding of representational content [3], global broadcasting of representational content [4], higher order thought [5], planning [6], the recursive processing of an ongoing orientational reference frame [7], and the attentional highlighting of representational content [8].
Today the American Society for the Study of Consciousness (ASSC) has 2 Journals on the topic. Consciousness and Cognition (Elsevier) and an e-journal called Psyche. The Journal of Consciousness Studies is published independently.
Consciousness can be viewed from the perspective of evolutionary biology as an adaptation, as a trait that increases fitness. [9] Consciousness also adheres to John Alcock's theory of animal behavioral adaptations because it possesses both proximate and ultimate causes. [10] The proximate causes for consciousness, i.e. how consciousness evolved in animals, is a subject considered by Sir John C. Eccles in his paper "Evolution of consciousness." He argues that special anatomical and physical properties of the mammalian cerebral cortex gave rise to consciousness. [11] Budiansky, by contrast, limits consciousness to humans, proposing that human consciousness may have evolved as an adaptation to anticipate and counter social strategems of other humans, predators, and prey.[12] Alternatively, it has been argued that the recursive circuitry underwriting consciousness is much more primitive, having evolved initially in pre-mammalian species because it improves the capacity for interaction with both social and natural environments by providing an energy saving "neutral" gear in an otherwise energy expensive motor output machine.[13] Once in place, this recursive circuitry may well have provided a basis for the subsequent development of many of the functions which consciousness facilitates in higher organisms, as outlined by Bernard J. Baars.[14]
While all this may be true, a case can also be made that consciousness is an architectural factor probably associated with the development of certain vertebrate phyla such as mammals and birds, and especially Simmian species, some of which have shown facility with language that while not as sophisticated as humans, still allows them some communication potential. In this theoretical framework, consciousness can be seen to be the result of a specific architecture of control mechanism perhaps based on a specific memory architecture. In any case consciousness can be separated into two types of consciousness, Primary Consciousness which most animals are thought to have, and Higher Order consciousness which it is thought only humans have. However no significant difference in brain architecture has been found to explain the [15]difference.