A couple of widely cited studies have found that the mere presence of cell phones interferes with social interactions and cognitive performance, even when not actively in use. These studies have important implications but have not yet been replicated, and also suffer from methodological shortcomings and lack of established theoretical frameworks to explain the observed effects. We improved the methodology used in a previous study of phone presence and task performance (Thornton et al. 2014), while testing an ‘opportunity cost’ model of mental effort and attention (Kurzban et al. 2013). We were unable to replicate Thornton et al.’s finding that presence of cell phones reduces performance in a specific cognitive task (additive digit cancellation). Moreover, contrary to our expectations, we found that participants who used their phones more, and who were more attached to them, found the tasks more fun/exciting and effortless, if they completed them with their phone present.