The information-processing approach to psychology characterizes human behaviour as meaning-oriented. Early psychophysicists proposed an unconscious process from stimuli to response. This sequence can be summarized as S --> O --> R. In this conceptualization, S represents the stimuli or environmental changes that impinge on the sensory systems; O represents the organism and its internal sensory and perceptual processes; and R symbolizes the responses the organism makes as a consequence of stimulation.
Under the influence of behaviourism in the early 20th century, psychologists abandoned research into "O" (organismic) processes in favour of the directly observable "S" (stimuli) and R (responses). For this reason behaviourism came to be known as S-R psychology, emphasizing only the observable associations between these two processes without inferring the nature of the connection.
With the development in recent decades of artificial intelligence (systems and computers that process information), the new fiield of cognitive psychology as emerged and revitalized interest in unobservable organismic variables. The information-processing approach, one perspective of cognitive psychology, suggests that these "O" processes are a valid and appropriate subject for scientific reasearch. Included among these are coginitive processes like perceiving, recognizing , thinking , imagining, and remembering . Many cognitive processes also take the form of "R" behaviours, influencing responses like problem-solving, decision-makig, and language.
An understanding of thinking is essential to comprehending cognitive processes. The effectiveness of thinking contributes to intelligence, a qulaity considered central to most aspects of human performance.