The four terms more or less mean the same thing, which is what we commonly call "learning"; but learning can take place at several levels of our mind/body.
As Dr. John C. Lilly explained so well, in our times it might be useful for understanding ourselves to think of mind/body as software/hardware respectively. It seems then that some of our memories (the longer-term memories) are more "hardwired" on us than others (shorter-term memories). The most important – to our survival and well-being – things somehow get encoded in/on our DNA (maybe with the help of epigenetic changes), which means they become inheritable. The memories that are absolutely required for our survival are what we call instincts. Then we gradually move to those memories that are not required by our species, but only by our personal self. These are not passed on to our children; they are only required for us, so they are only remembered by us.
[We must say here that these ideas might seem to contradict Dr Rupert Sheldrake's ideas of memory. Sheldrake believes that memories are not stored by biological means at all, but they are inherent in nature, in the form of an invisible to the eye field that he calls morphic field; this "surrounds" and flows through all existent physical forms and directs their development. It is what stores our memories, and the place that we retrieve "our" memories from (thus also keeps available to individuals memories of their ancestors). We believe that the two seemingly different theories –that of a biologically-based memory storage and that of memory being stored "in" an extra-biological field– are actually complementary to each other: Being simply that the morphic field is a level of memory storage finer than the DNA one; without necessarily any one of them not existing. This however contradicts Sheldrake's idea that the absence of the biological base does not influence the memory stored in the morphic field: it probably does, even if only up to a small degree.]
Another thing is that things that would otherwise be remembered can be "canceled out" or "deleted" (or rather more accurately, "hidden somewhere") by our brain if they are negative to our survival/well-being. This is referred to as "selective amnesia" and usually takes place in children.The four types of learning are described below.
During the early 19th century scientists had found that there is a window of time in a young animal's life where s/he is especially susceptible to have certain "ideas" imprinted on hir mind. The first of such ideas is probably the idea of who hir mother is. This idea gets imprinted early in a youngster's mind so that growing up it (or she or he) will follow its mother or its "mother figure" for safety and survival. I add the "mother figure" in the previous sentence because sometimes the young animal may not have its real mother (she may have died, for example) and the youngster may thus imprint a different animal as its mother (i.e. the young either gets adopted or it just follows older animals with the idea that they are its "mother"). The phenomenon of imprinting is instinctual. The animal that gets imprinted as "mother" in case that the real mother is absent is one that resembles the most the real mother, in behaviour and/or in appearance. The "first" demonstration of imprinting was made by Konrad Lorenz where he made baby geese imprint him as their "mother" (he did this just by being the first moving and caring thing the geese saw after their hatching) (see figure on the right with Lorenz and his geese). When there is no animal around to get imprinted as the "mother", the young animal may imprint the next closest thing resembling a mother; which could be an object. There is a popular example of a gosling that imprinted a ping pong ball as its mother that was rolled next to it as soon as it was born and it followed it around since. Another example is of a glider pilot who made several baby birds imprint his glider as their "mother" and followed him around in the air. Another interesting point is that when animals get sexually mature, they seem to be sexually attracted to what resembles their mother the most (a subject that occupied Freud), so in the case of the goose imprinting a ping pong ball as its mother, it later tried to have sex with it, ignoring the other geese. This is just an example of the power of imprinting, which basically means nothing more than "learning during a critical period of great suggestibility/acceptability"; this learning is far more powerful, or deeply imprinted (which is why this type of learning was called imprinting) than the forms of learning that we more consciously deal with.
Conditioning is the process by which an animal learns to respond in a specific manner to a specific stimulus. The most famous example of this is the case with Pavlov and his dog: Whenever Pavlov put food to his dog, he also played a bell; the dog eventually learned that the sound of the bell means food will come. Pavlov used an instrument on his dog which measured its stomach's secretions- in the end it showed that the sound of the bell alone –i.e. even in the absence of the food– could produce stomach secretions in his dog. The type of learning by which his dog paired the sound of the bell to the food is called "conditioning". And in this example conditioning was based on reward (the reward being the food it received). There can also be conditioning based on punishment: Where an animal can learn to respond accordingly to something that s/he has been conditioned to expect will be followed by a harmful stimulus (an everyday example of this conditioning: a mother conditioning her child not to do something by beating or shouting at hir whenever s/he does it).
When one understands the process by which hir mind/brain learn, then s/he can control selectively hir own imprints. As mentioned above, there is a certain period in the life of animals when they are very prone to imprinting. This is the time when the animals are still infants. It's the time when they learn who their mother is, among other important to their survival things. But in fact, this is not the only time when an animal is prone to imprinting. After some research, it was realised that we (us humans but also animals in general) are prone to imprinting at other times as well; these are situations when as it turns out to be our ego is shocked and temporarily "broken": when one lives a lonely and ascetic life for a long time, when one meditates for a very long time, when one had a near-death experience, etc. So, naturally, people who have realised this (from thousands of years back) had also realised that we can take control over our own imprints, if only we manage to take control over the situation of ego loss. Thus, they gathered the most powerful ego-dissolving methods they could find and experimented. They found that the process of selective imprinting worked, and that after the ego dissolution process, there is a certain window of time where a human can re-imprint stuff- sometimes (if the ego-dissolution method is powerful enough) as strongly as an infant imprints on its mother. So for example, they found that if they meditated enough (not a particularly powerful method but mentioned just as an example) they could then change parts of their personality that they otherwise couldn't (for example it could help them quit an unwanted habit). The modern Dr John Lilly, who probably worked on selective imprinting more scientifically than anyone, realised that it helps to understand ourselves if we regard our mind/brain combination as a kind of computer, since the process of human imprinting seems like the process of computer programming. In this case then, the part of the equation that realises this, and can control it if s/he wants, can be called the programmer.
"Brainwashing""What I tell you three times is true." - Lewis Carroll (author of Alice in Wonderland) "Sixty-two thousand four hundred repetitions make one truth" - Aldous Huxley, Brave New World
Not everyone sees selective imprinting as an opportunity to have fun with hirself. There are others who see it as an opportunity to gain more social power by controlling other people's (or animals') imprints. We commonly call this "brainwashing"; a term that helps us a bit to regard it as science fictional and not fully realise the degree by which it takes place in our world. Light cases of "brainwashing" (I'm relactant to remove its quotations because it's seems a bit of a silly term, but I can't recall of a better one right now) are advertisements; these use several tricks to make a product become as deeply imprinted in our minds as possible. One of the main advertisement tricks is repetition. Repetition of a statement like "Apple's Mac computers are the best" will eventually –in combination to other marketing tricks– get stuck in people's minds/brains until they start repeating it to their friends themselves: "Macs are the best, you know"; even if these are shitty machines. There are many other advertising tricks but we won't go into more detail here.
In more extreme cases of "brainwashing", more powerful methods are used. A person can be locked in solitary for long periods of time (a strong egolytic technique) and told repetitively the ideas that the "brainwasher" wants to make hir believe. The "brainwasher" also makes sure to combine hir ideas with hints of "safety"- for example "if only you understand this, you will be saved". The situation much resembles the case of Lorenz's geese: the person in solitary eventually reaches an egolytic state- taking hir "back" to the infant stage where s/he is lost, afraid, and willing to "grab" onto anything that resembles safety; a mother, a Lorenz, or in this case, the "brainwasher" and hir ideas. The subject's ideas that s/he once promised to hirself s/he will never change have now changed.