Chignell, M. H. | Search NASA

NASA NTRS1986

Knowledge-based load leveling and task allocation in human-machine systems

Conventional human-machine systems use task allocation policies which are based on the premise of a flexible human operator. This individual is most often required to compensate for and augment the capabilities of the machine. The development of artificial intelligence and improved technologies have allowed for a wider range of task allocation strategies. In response to these issues a Knowledge Based Adaptive Mechanism (KBAM) is proposed for assigning tasks to human and machine in real time, using a load leveling policy. This mechanism employs an online workload assessment and compensation system which is responsive to variations in load through an intelligent interface. This interface consists of a loading strategy reasoner which has access to information about the current status of the human-machine system as well as a database of admissible human/machine loading strategies. Difficulties standing in the way of successful implementation of the load leveling strategy are examined.

Chignell, M. H.↗

NASA NTRS1986

The effects of stress on attentional resources

A new perspective is presented from which to view the action of stress on human behavior. At a behavioral level, the action of stress is related to notions of human attention and an indication of an isomorphic relationship between modes of control at a physiological and behavioral level is presented. Examples of this phenomenon are extracted from performance under heat stress, since this is one of the most simple stress circumstances. It is suggested that stress sufficient to overcome adaptive capability, that is efficient homeostasis, acts to drain attentional resources. The manner in which such resources fail approximates that function typical of a positive feedback system, which also characterizes the breakdown of physiological response under severe environmental stress. The end point of this draining sequence is the absence of all attentional resources, which is taken to be unconsciousness, to be rapidly followed by the failure of physiological adaptability upon which life sustaining functions depend. This overall picture preserves the inverted-U shaped relationship between stress and performance, yet is in distinct contrast to the traditional arousal account of such behavior. The theoretical and practical ramifications of these observations are explored.

Hancock, P. A.↗