Analyzed whether an embodied conversational agent (ECA) has specific advantages when employed with privacy invading technologies such as a biometric security system. The study compares the effects of an ECA interface with the effects of conventional text-based and voice-based interfaces on user acceptance and usability (46 female and 44 male participants aged 20-55 years). An additional variable was whether the biometric system falsely rejected the user twice or whether it directly accepted him/her. Results of the 2 x 3 between-subjects design indicated that, although overall the text interface is rated most positive, voice and ECA yield distinct social effects: They have more advantageous consequences when problems arise - i.e., when the user is rejected repeatedly. The implications for social psychology in terms of applicability of new research methods as well as insights concerning fundamental research are discussed.