Scientific study
For many decades, consciousness as a research topic was avoided by the majority of mainstream scientists, because of a general feeling that a phenomenon defined in subjective terms could not properly be studied using objective experimental methods. In 1975 George Mandler published an influential psychological study which distinguished between slow, serial, and limited conscious processes and fast, parallel and extensive unconscious ones. The Science and Religion Forum 1984 annual conference, From Artificial Intelligence to Human Consciousness identified the nature of consciousness as a matter for investigation; Donald Michie was a keynote speaker. Starting in the 1980s, an expanding community of neuroscientists and psychologists have associated themselves with a field called Consciousness Studies, giving rise to a stream of experimental work published in books, journals such as Consciousness and Cognition, Frontiers in Consciousness Research, Psyche, and the Journal of Consciousness Studies, along with regular conferences organized by groups such as the Association for the Scientific Study of Consciousness and the Society for Consciousness Studies. Modern medical and psychological investigations into consciousness are based on psychological experiments (including, for example, the investigation of priming effects using subliminal stimuli), and on case studies of alterations in consciousness produced by trauma, illness, or drugs. Broadly viewed, scientific approaches are based on two core concepts. The first identifies the content of consciousness with the experiences that are reported by human subjects; the second makes use of the concept of consciousness that has been developed by neurologists and other medical professionals who deal with patients whose behavior is impaired.
class consciousness]
the state or activity that is characterized by sensation, emotion, volition, or thought;  mind in the broadest possible sense;  something in nature that is distinguished from the physical
the totality in psychology of sensations, perceptions, ideas, attitudes, and feelings of which an individual or a group is aware at any given time or within a particular time span—compare STREAM OF CONSCIOUSNESS
waking life (as that to which one returns after sleep, trance, fever) wherein all ones mental powers have returned . . . the part of mental life or psychic content in psychoanalysis that is immediately available to the ego—compare PRECONSCIOUS, UNCONSCIOUSThe Cambridge Dictionary defines consciousness as "the state of understanding and realizing something." The Oxford Living Dictionary defines consciousness as "The state of being aware of and responsive to ones surroundings. ", "A persons awareness or perception of something." and "The fact of awareness by the mind of itself and the world. "Philosophers have attempted to clarify technical distinctions by using a jargon of their own. The Routledge Encyclopedia of Philosophy in 1998 defines consciousness as follows:

Consciousness—Philosophers have used the term consciousness for four main topics: knowledge in general, intentionality, introspection (and the knowledge it specifically generates) and phenomenal experience... Something within ones mind is introspectively conscious just in case one introspects it (or is poised to do so). Introspection is often thought to deliver ones primary knowledge of ones mental life.