Thesis - Instituto de Telecomunicações

Chapter 2State of the ArtIn this chapter we provide contextual information on biometrics technologies by introducingthe main concepts and covering in detail recent work on behavioral biometrics. We also focusattention on the present trends in the area, overviewing works on multimodal-biometricsand continuous biometrics.The Biometrics research field was initially focused on the physical characteristics ofthe human being. Only recently, human behavior started to gain attention, being usedon biometric systems for commercial application. Behavioral biometrics traits were usedin combination with other physical characteristics to create more robust multibiometricsystems.Human behavior is an area of research in psychological studies [155], where the focusis on understanding the conscious or unconscious reaction of the human being in relationto his environment [61]. Behavior happens in time. It refers to the flow of events thatoccur in a situation. This concept is studied in a multi factorial approach where emotions,values, ethics and genetic characteristics (among others), congregate to present the complexbehavior of the human being. Biology also covers behavior in the ethology branch.Behavior is the basis for this research. Typically the source for the identification ofa human being has been some physical characteristic (such as fingerprint or iris pattern).When a trait is related to a dynamic action of the user, we call it a behavioral biometrictrait.The Internet is a place where human behavior can be easily acquired and recorded.11