ABSTRACT
This chapter explains how individual operators contribute to the reliability of collective activity through their error management. Error management concerns all cognitive activities and material actions whose object is error itself: it includes prevention, detection, identification, evaluation, supervision and recovery. The chapter analyzes the role played by observers in facing collective work with regards to operational memory and shared situation awareness, the status of possible departures from prescribed procedures, and attribution of agency in events related to safety. For the relevance of the model of ecological safety to be demonstrated in the case of collective action, some development needs to be made to the mechanism of what has been called 'cognitive compromise'. The ecological safety model and the notion of cognitive compromise were developed and studied in the frame of individual activity. Globally, data show that individuals contribute to the reliability of collective activity through process-sharing characteristics of the properties involved through individual error management.
