andy_clark's picture
Professor of Cognitive Philosophy, Department of Philosophy and Department of Informatics, University of Sussex, Brighton, UK; Author, Surfing Uncertainty: Prediction, Action, and the Embodied Mind
The Input-Output Model of Perception and Action

It's time to retire the image of the mind as a kind of cognitive couch potato—a passive machine that spends its free time just sitting there waiting for an input to arrive to enliven its day. When an input arrives, this view suggests, the system swings briefly into action, processing the input and preparing some kind of output (the response, which might be a motor action or some kind of decision, categorization, or judgement). Output delivered, the cognitive couch potato in your head slumps back awaiting the next stimulation.

The true story looks to be almost the reverse. Naturally intelligent systems (humans, other animals) are not passively awaiting sensory stimulation. Instead, they are constantly active, trying to predict the streams of sensory stimulation before they arrive. When an 'input' (itself a dodgy notion) arrives on the scene, our pro-active cognitive systems were already busy predicting its shape and implications. Systems like that are already (pretty much constantly) poised to act, and all they need to process are any sensed deviations from the predicted state.

Action itself then needs to be reconceived. Action is not so much a response to an input ('input-output-stop') as a neat and efficient way of selecting the next 'input', driving a rolling cycle. These hyperactive systems are constantly predicting their own upcoming states, and moving about so as to bring some of them into being. In this way we bring forth the evolving streams of sensory information that keep us viable (keeping us fed, warm, and watered) and that serve our increasingly recondite ends.

As ever-active prediction engines these kinds of minds are not, fundamentally, in the business of solving puzzles given to them as inputs. Rather, they are in the business of keeping us one step ahead of the game, poised to act and actively eliciting the sensory flows that keep us viable and fulfilled.

Just about every aspect of the passive input-output model is thus false. We are not cognitive couch potatoes so much as proactive predictavores, forever trying to stay one step ahead of the incoming waves of sensory stimulation. Keeping this in mind will help us to design better experiments, build better robots, and appreciate the deep continuities binding life and mind.