Proper allocation of tasks between humans and machines is
an important component of user centred design. First identify
which tasks can only be allocated to either the machine or
human (mandatory allocation), and then provisionally allocate
tasks on either a permanent and dynamic basis. This provisional
allocation should then be evaluated and revised if necessary.
Tasks should be allocated to humans and machines in a way
that best combines human skills with automation to achieve
task goals, while supporting human needs.
Context analysis and task
analysis should be used to identify the task structure
and demands, the knowledge needed to perform the tasks, environmental
constraints, functional and safety requirements, and any other
Mandatory allocation can be identified from the task
- to humans due to technical infeasibility or ethical or
- to machines due to demands exceeding human capabilities
or a hostile environment
Permanently allocate tasks based on factors such
as task criticality, cost, training or knowledge requirements,
or task unpredictability.
Dynamically allocate tasks based on factors such
as human workload, the need for cognitive support, individual
differences in users, changing capacity of the user, or organisational
Jobs must be designed from the tasks based on factors such
as responsibility, task variety, interference between and
within tasks, communication between users, and individual
The provisional allocations and jobs should be evaluated
based on factors such as: safety, system performance, usability,
cost, job satisfaction and human well-being, acceptance by
users, management and society and social impact. The evaluation
findings should be used to review and revise the provisional
allocations which should then be re-evaluated.
This procedure is based on:
Tasks between Humans and Machines in Complex Systems Mark-Alexander
Sujan and Alberto Pasquini, 4th International Conference on
Achieving Quality in Software, Venezia, 1998
The prototypes produced for
evaluation of task allocation can
be included as part of the iterative design
process. This is followed by implementation.
Older, M.T., Waterson, P.E. and Clegg C.,W. (1997) A critical
assessment of task allocation methods and their applicability.
Ergonomics, 40(2): 151-171.
Ip, W.K., Damodaran, L., Olphert, C.W. & Maguire, M.C.
(1990). The use of task allocation charts in system design
- a critical appraisal. In D. Diaper, G. Cockton, D. Gilmore
& B. Shackel, Eds. Human-Computer Interaction INTERACT'90,
pp. 289-294. Amsterdam: North-Holland.