ARTIFICIAL ‘ SIGNALS’ AS AN AID TO AN INSPECTION TASK

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Abstract
The detection of faults or ‘ signals ’ in inspection tasks can be greatly improved by adding artificial signals with rewards for their detection. Without such rewards they are ineffective. For the best combination of highest real signal detection with minimum increase in false reports the artificial signals should be identical to the real ones. Nevertheless, adding different artificial signals may be much better than adding none at all. These conclusions arise from a study in which the ability to detect eight ‘ real ’ signals in a one-hour inspection task was greatly enhanced by adding 40 artificial signals which were identical to the real ones and about success in the detection of which the subject was given knowledge (‘knowledge of results’). Signal detection rose from 40 to 90 per cent of all presented. A reduced advantage remained if (a) the artificial signals were made different from the real ones (62 per cent real signal detection) and (b) if the feedback of knowledge of results was reduced (72 per cent). (c) Virtually no advantage remained if the feedback was removed altogether (47 per cent). The number of false reports increased greatly with different artificial signals added, but only moderately with identical ones. This suggests that the latter enhance both motivation and the ability to discriminate the real signal, whereas different artificial signals may improve motivation only. Signal detection improved with practice, but only in the conditions where knowledge of results was given about the detection of artificial signals.