Cookie disclaimers: Dark patterns and lack of transparency

While cookie disclaimers on websites have been proposed to ensure that users make informed decisions regarding consenting to data collection via cookies, such informed consent is hindered by several factors. One of them is the presence of so-called dark patterns, that is, design elements that are used to lead users to accept more cookies than needed and more than they are aware of. The second factor is lack of transparency on behalf of the service providers with regards to what happens if the user does not consent to cookie usage even despite dark patterns nudging them to do so. The contributions of this paper are (1) evaluating the efficacy of several of these factors while measuring actual behaviour; (2) identifying users' attitude towards cookie disclaimers including how they decide which cookies to accept or reject; (3) assessing the behaviour of websites regarding storing non-necessary cookies despite user's consent. We show that different visual representation of the reject/accept option have a significant impact on users' decision. We also found that the labelling of the reject option has a significant impact. In addition, we confirm previous research regarding biasing text (which has no significant impact on users' decision). Our results on users' attitude towards cookie disclaimers indicate that for several user groups the design of the disclaimer only plays a secondary role when it comes to decision making. We furthermore show that even without user's explicit consent, the majority of websites we investigated still uses non-necessary cookies. We provide recommendations on how to improve the situation for different stakeholders, namely, for developers and policy makers.