The research in Human Computer Interaction (HCI) has nowadays extended its attention to
the study of persuasive technologies. Following this line of research, in this paper we focus
on websites and mobile applications in the e-commerce domain. In particular, we take them
as an evident example of persuasive technologies. Starting from the hypothesis that there is
a strong connection between logical fallacies, i.e., forms of reasoning which are logically
invalid but psychologically persuasive, and some common persuasion strategies adopted
within these technological artifacts, we carried out a survey on a sample of 175 websites and
101 mobile applications. This survey was aimed at empirically evaluating the significance of
this connection by detecting the use of persuasion techniques, based on logical fallacies, in
existing websites and mobile apps. In addition, with the goal of assessing the effectiveness
of different fallacy-based persuasion techniques, we performed an empirical evaluation
where participants interacted with a persuasive (fallacy-based) and with a non-persuasive
version of an e-commerce website. Our results show that fallacy-based persuasion
strategies are extensively used in existing digital artifacts, and that they are actually effective
in influencing users’ behavior, with strategies based on visual salience manipulation (accent
fallacy) being both the most popular and the most effective ones