A mock crime experiment was designed in which 100 participants were randomly assigned to five conditions: four experimental conditions in a 2 × 2 factorial design (two guilt conditions—guilty or informed innocents, crossed with two incentive level conditions—with or without a promised reward for proving innocence), and one control condition of uninformed innocents. Along with the common dependent polygraph measures, attitudes towards cooperating with the test were assessed. Results indicated that the informed innocents preferred to cooperate whereas guilty participants preferred to try and obstruct the test. These tendencies were amplified among participants who were promised a reward. The cooperative choice attenuated electrodermal responses to the critical items. Respiration measures were sensitive to the incentive level manipulation. Implications of the results for future research and for actual detection of information tests were discussed.