Antoine Boutet (Inria), Tao Beaufils (Inria)
Content personalization is ubiquitous on the web and mobile applications. However, the mechanisms that practically control this personalization by the different parties in the targeted advertising ecosystem remain unclear, raising serious questions about possible user manipulations to encourage them to take certain actions (e.g., consent to cookies, purchase a product). Due to its user-centric nature, it is technically difficult to collect this personalization in order to analyze it on a large scale. In this paper, we present STETOSCOPE (underSTand targETing and manipulatiOnS via COllaborative Private data collEction), a participative mobile application to analyze content personalization. Instead of relying on bots for data collection (which are subject to detection by platforms and may induce bias in the content), STETOSCOPE engages individuals by providing them with data collection campaigns linked to legitimate questions posed by citizens (e.g., is there price discrimination on this platform? Is this incentive message trustworthy?). A data collection campaign guides the user to specific web pages or mobile applications where a screenshot is triggered by the participant to collect the targeted information. These screenshots are then analyzed on a backend server to draw conclusions. This participatory application allows users to be involved in issues related to different forms of personalization on mobile, such as the analysis of dark patterns, price or search discrimination, the exchange of personal information with third parties, trust in incentive messages, or information bubbles for instance. To assess the prospects and limitations of the STETOSCOPE, we conducted preliminary data collection campaigns on e-commerce, bus and hotel booking, and recruitment platforms. Our preliminary results show evidence of search discrimination on most platforms, evidence of price discrimination on AliExpress, and evidence of fake discounts during Black Friday on Temu and on many ecommerce platforms before and after Christmas.