Regulation of division of labour between cognitive systems controlling action

The brain has evolved a division of labour amongst component systems which link different sorts of processing with precise actions. Debate is over cen tralized versus decentralized control at different processing levels, from cognitive systems to motor-control systems. With simultaneous activation of alternative expert systems which link (a) picture-processing with drawing and (b) reading with writing, decentralized modelling predicted both the av eraging of action-production times and additive effects of neural noise. Su ch modelling has the advantage of being able to measure the cost of regulat ion both within and between systems, in a common metric of performance vari ability. That commonality strengthens the trend to regard the brain as a di stributed super-system with a great deal of regulation done towards the out put end. (C) 2000 Elsevier Science B.V. All rights reserved.