This study investigates whether knowledge gains from news post exposure are different when scrolling through a social media newsfeed on a smartphone compared to a desktop PC. While prior research has mostly focused on new platforms people receive news on (e.g., social media) for political learning, first indications exist that device modality (i.e. exposure on smartphone vs. desktop PC) itself alters news exposure patterns. With the help of mobile eye-tracking, this study investigates cognitive processes that enable learning from exposure among a student sample (n = 122). We extend prior research on the mediating role of attention for learning by investigating whether different frames of political news posts can attenuate this indirect relationship. The study uses a 2 × 2 mixed-subjects design, with the device being a between-subjects condition and news frames (episodic vs thematic) being a within-subjects condition. We find smaller knowledge gains from smartphone news exposure, which cannot be explained by differences in visual attention.