Effects of Monetary Incentives on Performance of Nonprofessionals in Document-Examination Proficiency Tests

In September 1997 we reported on a comprehensive proficiency test administered to three groups of professional document examiners (105 individuals). Each test-taker performed 144 pairwise comparisons of original handwritten documents and matched together pairs that in his/her opinion were generated by the same hand. The test was also administered to a control group of nonprofessionals (41 individuals) whose educational profile was similar to that of the tested professionals. These nonprofessionals were motivated through a monetary incentive plan ($25 gain for each correct match: $25 fine for each erroneous match; $10 fine for failure to match documents created by the same hand). In this paper, we report on a subsequent study, aimed to discover whether changes in the monetary incentive scheme would affect the performance of nonprofessionals, and whether these schemes would close the performance gap between professionals and nonprofessionals. We administered the 1997 test again, this time to four groups of nonprofessionals (132 subjects), using four different incentive schemes (including the one used originally). We found that the four sets of data obtained under different incentives were indistinguishable, in the sense that differences between the test scores were not statistically significant. We conclude that the performance of nonprofessionals in our proficiency test was relatively insensitive to the monetary incentive scheme.