Abstract: The need for holistic systems analysis has been emphasized by Checkland in his Soft Systems Methodology for information systems engineering and by Sommerville and others in the software engineering approach for sociotechnical systems. Currently, more and more emphasis is put on understanding and considering the behaviours of humans within information systems. The lecture is concerned with the following two ways of how the behaviours of humans can be represented, analysed and predicted: by modelling and simulating information systems comprising humans at a macro (societal) level and by modelling and simulating the behaviours of humans within information systems at a micro (human brain) level. The lecture is illustrated by different case studies from industry and public sector.