a feature differs in deterrence value for each class of counterfeiter, depending on the technology that each employs, as summarized in Table 4-1.

Likewise, a feature’s detectability depends on the detection method employed, the nature of the currency transaction, and the education, training, and cognitive capabilities of the recipient of the note. While many transactions take place in a venue in which unassisted human authentication is the preferred (or only) option—such as in a store, restaurant, or taxi—an increasing number of transactions involve alternative assisted methods. These assisted methods might deploy a portable, low-cost, nonproprietary basic device that is generally available and easy to use, or a dedicated machine reader such as an automatic currency acceptor that does not involve a human cash handler. Examples of existing simple devices, of varying effectiveness and popularity, include starch pens, magnifying glasses, and ultraviolet penlights. Given the increasing incidence of human, device-assisted authentication abroad and in the United States, an evaluation of potential new features must include their authentication by simple devices and machines as well as by unassisted humans. Table 4-2 summarizes the leading authentication concepts by type of cash handler—that is, by currency user.

New feature concepts can span a wide range of technological readiness, from ultralow technology to highly innovative possibilities. Of the many potential feature concepts that emerged from the committee’s brainstorming during the course of the study, a subset was ranked for presentation in the report by the feature-assessment process described below. The features evaluated were subsequently