In a biometric access control system, what problem may occur if the system is set too high, like at point B?

In a biometric access control system, setting the threshold for acceptance too high can lead to a significant increase in the false rejection rate. However, in the context of your provided answer, it's essential to clarify that the correct understanding would be regarding the implications of a low threshold rather than a high one. Generally, if a system is set at too high of a threshold, it dramatically reduces the likelihood of mistakenly accepting an unauthorized user (false acceptance).

Conversely, adjusting the threshold too high means that legitimate users may fail to be recognized, resulting in increased false rejections where authorized users are denied access. This can lead to a frustrating experience for users who know they should have access but are incorrectly denied entry. Consequently, it also highlights potential issues related to the authentication process, where genuine attempts may not be processed effectively due to the stringent requirements imposed by the threshold.

Moreover, user experience deteriorates when individuals are frequently rejected, which aligns closely with high thresholds. The access control system is designed to ensure that both security and user convenience are balanced, and setting thresholds too strictly disrupts this balance. Therefore, while false acceptance is lowered, the negative consequences manifest as high false rejections and a poor user experience.