Automatic processing refers to thinking that is nonconscious, unintentional, involuntary, and effortless.
Automatic processing is what Psychologists call processing of information that guides behavior , but without conscious awareness, and without interfering with other conscious activity that may be going on at the same time: for example, driving slowly down a street (automatic processing) while looking for a specific address (conscious processing)
Moreover, Automatic processing refers to "implicit" or intuitive thinking that is effortless, habitual, and without awareness.
Other definition:
Automatic Processing is the the carrying out of a cognitive task with minimal resources. Typically, automatic processing occurs without intention, interferes minimally with other cognitive tasks , and may not involve conscious awareness.