Enhancing banknote authentication by guiding attention to security features and prevalence expectancy

ll banknotes have security features which are intended to help to determine whether a banknote is false or genuine. Typically however, the general public has limited knowledge of where on a banknote these security features can be found. Here we tested whether counterfeit detection can be improved with the help of salient cues, designed to guide bottom-up visuospatial attention. We also tested the influence of the participant’s a priori level of trust in the authenticity of the banknote. In an online study (N=422), a demographically diverse panel of Dutch participants distinguished genuine banknotes from banknotes with one (left- or right-sided) counterfeited security feature. Either normal banknotes (without novel design elements) or banknotes that contained a salient cue (a pink rectangular frame) were presented for 1s. To manipulate the participant’s level of trust, trials were administered in three blocks, whereby at the start of each block, participants were instructed that either one third, one half, or two thirds of the upcoming banknotes were counterfeit (though the true ratio was always 1:1). We hypothesized (i) that in the presence of a salient cue, counterfeits would be better detected when the cue was valid (whereby the location of the salient element matched the location of the counterfeited security feature) than when it was invalid; and (ii) that this effect would be stronger with lower trust. Our hypotheses were partly confirmed: counterfeit detection improved with valid cues and decreasing trust, but the level of trust did not modulate the cueing effect. As the overall detection performance was rather poor, we replicated the study with a sample of university students (N=66), this time presenting stimuli until response. While indeed observing better overall performance, all other patterns were replicated. Two lessons can be learned here. Firstly, as lower trust yields better authentication accuracy, central bankers may see merit in raising awareness about the existence of counterfeit banknotes. Secondly, our findings provide a proof of concept for the idea that bottom-up saliency can be used to aid banknote authentication.