Counterfeit detection for new and old currency designs

To test the effectiveness of counterfeit deterrence features recently introduced in US currency, observers were asked to discriminate genuine from counterfeit bills using a two-alternative forced-choice task. In Experiment 1, observers judged $100s with the new and old designs after receiving training in the deterrence features of each design. The counterfeits were representative of two common print processes: inkjet and offset printing. Judgments were made on whole bills, on individual features with the whole bill unmasked, and on individual features with only that feature visible. In Experiment 2, different observers judged $100s without any training. They then were trained and judged $50s and $20 bills. Taken together, the two experiments indicate that people are good at detecting counterfeits, that inkjet counterfeits are easier to detect than offset counterfeits, and that counterfeits of the newly designed bills are easier to detect than counterfeits of the older series. The design improvement was greatest with $100 bills and, to a lesser extent, $50 bills. Improvement was minimal with $20 bills, very likely because observers were very accurate for both series of $20s. Finally, some deterrence features were more useful than others in aiding discriminations.