Active Imagination is a specific technique in Jungian work, a type of meditation, which essentially allows for the experience of dreaming while awake. While there are now numerous books published on the practice, active imagination remains on of the least know aspects of Jung’s enterprise, though The Red Book was developed mainly through the technique. In fact, much of what today is considered Jungian theory was first formulated for Jung in his experiences of active imagination.
To experience active imagination you need to lower your threshold of consciousness to place which resembles the first waking moments each day. This type of consciousness is known as the hypnogogic. Jung found it useful to focus on moods which were irritating him. By focusing his attention toward what he would prefer to flee, he soon learned that he would experience dreamlike experiences, with the peculiar twist of not being asleep.
Another method I find helpful is to return to a specific dreamscape, and to attend to the details. Following the teaching of Murray Stein on active imagination, the goal or rules are simple: “let what comes, come…and if it moves follow it.”
It is important to render these experiences in word or image (some will employ movement or sound). In fact, it is possible to write the experience down as it is happening, as one can remain in both locales, that of the unfolding vision, and the place where one is seated, simultaneously.
Active imagination is considered an advanced technique for those engaged in Jungian psychoanalysis and the literature gives some caution about how the technique can be unfruitful, misguided and even dangerous.
It is possible to experience the technique in group settings. Robert Bosnak has developed a embodied active imagination (ebook in pdf format on the technique) which I have led many through successfully, including adolescents.