Sigmund Freud didn't exactly invent the idea of the conscious versus unconscious mind, but he certainly was responsible for making it popular and this was one of his main contributions to psychology.
Freud (1900, 1905) developed a topographical model of the mind, whereby he described the features of the mind’s structure and function. Freud used the analogy of an iceberg to describe the three levels of the mind.
Freud (1915) described conscious mind, which consists of all the mental processes of which we are aware, and this is seen as the tip of the iceberg. For example, you may be feeling thirsty at this moment and decide to get a drink.
The preconscious contains thoughts and feelings that a person is not currently aware of, but which can easily be brought to consciousness (1924). It exists just below the level of consciousness, before the unconscious mind. The preconscious is like a mental waiting room, in which thoughts remain until they 'succeed in attracting the eye of the conscious' (Freud, 1924, p. 306).
This is what we mean in our everyday usage of the word available memory. For example, you are presently not thinking about your mobile telephone number, but now it is mentioned you can recall it with ease. Mild emotional experiences may be in the preconscious but sometimes traumatic and powerful negative emotions are repressed and hence not available in the preconscious.
Finally, the unconscious mind comprises mental processes that are inaccessible to consciousness but that influence judgements, feelings, or behavior (Wilson, 2002). According to Freud (1915), the unconscious mind is the primary source of human behavior. Like an iceberg, the most important part of the mind is the part you cannot see.
Our feelings, motives and decisions are actually powerfully influenced by our past experiences, and stored in the unconscious.
Freud applied these three systems to his structure of the personality, or psyche – the id, ego and superego. Here the id is regarded as entirely unconscious whilst the ego and superego have conscious, preconscious, and unconscious aspect.
While we are fully aware of what is going on in the conscious mind, we have no idea of what information is stored in the unconscious mind.
The unconscious contains all sorts of significant and disturbing material which we need to keep out of awareness because they are too threatening to acknowledge fully.
The unconscious mind acts as a repository, a ‘cauldron’ of primitive wishes and impulse kept at bay and mediated by the preconscious area. For example, Freud (1915) found that some events and desires were often too frightening or painful for his patients to acknowledge, and believed such information was locked away in the unconscious mind. This can happen through the process of repression.
The unconscious mind contains our biologically based instincts (eros and thanatos) for the primitive urges for sex and aggression (Freud, 1915). Freud argued that our primitive urges often do not reach consciousness because they are unacceptable to our rational, conscious selves. People has developed a range of defence mechanisms (such as repression) to avoid knowing what their unconscious motives and feelings are.
Freud (1915) emphasized the importance of the unconscious mind, and a primary assumption of Freudian theory is that the unconscious mind governs behavior to a greater degree than people suspect. Indeed, the goal of psychoanalysis is to reveal the use of such defence mechanisms and thus make the unconscious conscious.
Freud believed that the influences of the unconscious reveal themselves in a variety of ways, including dreams, and in slips of the tongue, now popularly known as 'Freudian slips'. Freud (1920) gave an example of such a slip when a British Member of Parliament referred to a colleague with whom he was irritated as 'the honorable member from Hell' instead of from Hull.
Initially, psychology was sceptical regarding the idea of mental processes operating at an unconscious level. To other psychologists determined to be scientific in their approach (e.g. behaviorists) the concept of the unconscious mind has proved a source of considerable frustration because it defies objective description, and is extremely difficult to objectively test or measure.
However, the gap between psychology and psychoanalysis has narrowed, and the notion of the unconscious is now an important focus of psychology. For example, cognitive psychology has identified unconscious processes, such as procedural memory (Tulving, 1972), automatic processing (Bargh & Chartrand, 1999; Stroop, 1935), and social psychology has shown the importance of implicit processing (Greenwald & Banaji, 1995). Such empirical findings have demonstrated the role of unconscious processes in human behavior.
However, empirical research in psychology has revealed the limits of the Freudian theory of the unconscious mind, and the modern notion of an 'adaptive unconscious' (Wilson, 2004) is not the same as the psychoanalytic one. Indeed, Freud (1915) has underestimated the importance of the unconscious, and in terms of the iceberg analogy there is a much larger portion of the mind under the water. The mind operates most efficiently by relegating a significant degree of high level, sophisticated processing to the unconscious.