Automatic processing is generally defined as response biases that are well learned, relatively not demanding and thus not strongly effected by concurrent load, and difficult to change, ignore, or suppress. Conversely, controlled processing is generally defined as responses that are more cognitively demanding, sensitive to concurrent load, and more easily changed by an individual. The concept of automatic and controlled processing may be associated with a variety of other constructs, including executive function, heuristics, and dual-process theory.
Schneider, W., & Shiffrin, R. M. (1977). Controlled and automatic human information processing: I. Detection, search, and attention. Psychological Review, 84(1), 1-66. doi:10.1037/0033-295X.84.1.1
Shiffrin, R. M., & Schneider, W. (1977). Controlled and automatic human information processing: II. Perceptual learning, automatic attending and a general theory. Psychological Review, 84(2), 127-190. doi:10.1037/0033-295X.84.2.127