Automatism is a surrealist technique involving spontaneous writing, drawing, or the like practiced without conscious aesthetic or moral self-censorship. Automatism has taken on many forms: the automatic writing and drawing initially (and still to this day) practiced by surrealists can be compared to similar, or perhaps parallel phenomena, such as the non-idiomatic improvisation of free jazz.
This type of technique was developed by a surrealist as a means of expressing the subconscious. From what I understand I think that automatism is like free drawing of the mind. Wherever you hand goes on the paper is where your mind isn’t. You’re moving your hand subconsciously… thats soo weird. Its like just taking your pencil and taking paper and letting your mind and limbs go free, let them do whatever they please.
In the description of automatism it says : In applying chance and accident to mark-making, drawing is to a large extent freed of rational control. Hence the drawing produced may be attributed in part to the subconscious and may reveal something of the psyche, which would otherwise be repressed. Surrealist artists often found that their use of ‘automatic drawing’ was not entirely automatic, rather it involved some form of conscious intervention to make the image or painting visually acceptable or comprehensible.
I like this technique…its very unique and unpredictable. Because when you let your hands draw whatever your mind is thinking or not thinking with out really looking at your masterpiece, you’ll be amazed with what you’ve created. Sometimes your subconsciousness may not cease to amaze you.
Here’s an example of automatism : 
