Adaptive unconscious

The adaptive unconscious is a set of unconscious mental processes influencing judgment and decision making. It is different from conscious processing: it is faster, effortless, more focused on the present, but less flexible. It can be described as a quick sizing up of the world which interprets information and decides how to act very quickly and outside the conscious view. 
In some theories of the mind, the unconscious is limited to "low-level" activity, such as carrying out goals which have been decided consciously. In contrast, the adaptive unconscious is thought to be involved in "high-level" cognition such as goal-setting as well.
The term 'adaptive unconscious' suggests it has survival value and hence is an adaptation which was strongly selected in the past. Indeed, for much of vertebrate evolution, all mental activity was unconscious. No-one supposes that fish have consciousness. Thus our consciousness is added to an already-existing set of mechanisms which operate but whose operation is normally not felt by us.p23
Implicit learning.
Implicit (or 'tacit') learning is when a person learns without knowing it happens. 
An important point made by Reber is that "implicit learning is a fundamental 'root' process, one that lies at the very heart of the adaptive behavioral repertoire of every complex organism". What that means is that implicit learning is very much more ancient than the conscious type of learning that we, as humans, normally notice.
This is an expanding field of research. 
The classic examples are the acquisition of language and the process of socialization. Children learn to speak their native language and become socialized to their society without being conscious of the principles which guide their behaviour.
There has been much debate on the bare existence of implicit learning because of the fact that knowledge gained is not verbalizable. Little research has been conducted on the requirements for the process of implicit learning to take place.
Evidence 1: case studies.
The evidence for there being such a thing as the adaptive unconscious is a series of case studies which are hard to explain any other way.
The Kouros fraud.
After many scientific tests were done on an early Greek statue, the Getty Museum was about to buy it. However, a small group of experts looked at it and said immediately "It's a fake". Eventually, it was found to be a fake. The question was, how could anyone beat the battery of scientific tests just by looking at it? The sceptics were asked how they did it. One said "It doesn't look old, as if it had been centuries under the ground. Another said "Its fingernails don't look right". Apparently they had all seen something which triggered a doubt. Psychologists thought this might be an ancient mental mechanism which has survival value.
The fireman's 'ESP'.
A firefighter in Cleveland answered a routine call with his men. It was in a kitchen in the back of a one-story house. The firefighters broke down the door, laid down their hose, and began dousing the fire with water. This had little effect. As the fire lieutenant recalls, he suddenly thought to himself, "There's something wrong here", and he immediately ordered his men out. Moments after they fled, the floor they had been standing on collapsed. The fire had been in the basement, not the kitchen as it appeared. When asked how he knew to get out, the fireman thought it was ESP. What is interesting is that the fireman could not immediately explain how he knew to get out. From the 'locked door' in our brains, the fireman just 'blinked' and made the right decision. In fact, had he thought consciously about the situation, he would probably have lost his life and the lives of his men.p125
Exceptional intuition.
In a similar way, there are people who can repeatedly do something which seems amazing. It really is possible to spot who is lying, for instance, and it is a skill which can be trained and improved. It is possible to predict which couple will divorce and which will not. The time taken for each decision is short, and (to an observer) the amount of information available to the person making the decision seems very little.
Analysis paralysis.
'Thin slice' decisions based on limited information are one end of a scale. At the other end is the confusion caused by too much unorganised information: 'analysis paralysis'. There are many examples of the latter state being bad for decision taking.
Evidence 2: experiments.
A number of experiments have been done which strongly support the idea of an adaptive unconscious. The basic idea is to bias the unconscious, and see if it affects behaviour.
Scrambled sentences.
Subjects sort out four-word sentences from sets of five word. They concentrate on getting the sentences right. Unknown to them the unused word gives their minds a subtle bias. From one set, with extra words Florida, old, lonely, forgetful, wrinkle (and some neutral words) the experimental group "walked more slowly away from the experimental room".p54 The priming words had biased them to "think elderly". The idea is that of John Bargh.
Priming affects test results.
Priming significantly affects test results. A group being tested about the Trivial Pursuit game were split in two. One group was first asked to think about what it would mean to be a professor. They got 55.6% of the questions right. The other half were first asked to sit and think about soccer hooligans. They scored 42.6%. Other tests indicated that the two groups had similar mental ability. The difference between the results is highly significant.p57
Another test was even more startling. Black college students were given 20 questions from the Graduate Record Examination, a standard test used for entry to graduate schools in the U.S.A. Students were given a pretest questionnaire. One group were asked to identify their race; the other was not. The first group scores were "half" that of the second group. The experimenters later asked whether the question about their race affected them. They all said 'no' and added something like "You know, I just don't think I'm smart enough to be here".p59 Of course, this is of the greatest significance socially. Notice that, once again, the individuals did not notice consciously what had happened unconsciously.
What the ventromedial does.
The ventromedial area of the cerebral cortex is a small bit at front behind the nose. Neurologist Antonio Damasio studied patients who had damage to this area of the brain. 
People with damage to this area are still rational and as intelligent as before. But they lack judgement, and find it very difficult to make decisions. In fast-moving situations, the ability to make fairly good decisions rapidly is more important than making perfect decisions after lengthy thought. It can be a matter of survival.
Characteristics.
Unconscious processes have a number of typical features which are quite different from the conscious processes.
Access.
Obviously, by definition, unconscious processes are less available than conscious processes. Yet there is traffic between the two. For example, there is a well-known tendency for all training to move from halting, difficult conscious steps to smooth, semi-automatic performance. That, as Anderson recognised, is a shift from conscious to unconscious control as mastery is achieved. Anderson's key distinction is between 'declarative knowledge' (knowledge we are aware of and can talk about) and 'procedural knowledge', which guides action and decision-making, but which happens outside of conscious 'view'.
Learning also takes place in ways which are entirely unconscious to us at the time. A classic example is the way children learn their native language between the ages of about 18 months and four years. They do not study language the way an older person does. It happens automatically. Another example: people under anaesthetic can hear and be influenced by what they hear.
Access to memory also happens unconsciously: even when we try to remember, the actual process is unconscious. It can happen entirely unconsciously. An early experiment by Korsakoff on patients with loss of conscious memory showed this. He gave one patient mild electric shocks. Later, when Korsakoff returned, the patient had forgotten all about it. Yet when he saw the apparatus, the patient showed anxiety, and accused him of wanting to give him an electric shock. The experiment has been repeated since in various ways.
Failures of judgement.
It is easy to show that our snap judgements can also be quite wrong, especially when we are overwhelmed with information, or when we come to the decisions with unconscious bias and prejudice.
In experiments, subjects give verbal explanations of their own mental processes—for example why they chose one thing rather than another—as if they could directly introspect (look inside) the causes of their ideas and choices. This 'introspection illusion' may cause differences between the self and other people, because people trust these unreliable introspections when forming attitudes about themselves but not about others.