Dance of the thumbs (DOT): Kinematic characterization of digital intentions on the smartphone

In daily life, humans produce complex and subtle hand and finger movements, such as playing instruments or typing on keyboards. In recent decades, digital technologies, particularly smartphones with touchscreen interfaces, have become ubiquitous, radically changing the way individuals communicate and search for information. Typing on smartphones is common in two main domains: (i) content consumption (e.g., browsing, reading news), and (ii) content generation (e.g., writing messages, posting on social media). Recent findings show that simply observing typing on a smartphone can reveal whether a user is consuming or generating content, suggesting that distinct kinematic cues characterize the two intentions. Leveraging advanced 3D motion analysis techniques, this study analyzes the temporal, spatial, and velocity characteristics of thumb movements during typing on a smartphone, with the goal of revealing the underlying structure of digital intentions. Fourteen naïve participants were recorded while typing seven sentences on: (i) Google (content consumption), and (ii) WhatsApp (content generation). Anatomical landmarks were defined to develop a new 3-D model: the Dance of Thumbs (DoT). Movements of both thumbs were captured using six infrared cameras and a 3-D motion analysis system. Results indicate that (i) significant kinematic differences exist between typing for content consumption and generation, and (ii) motor efficiency is higher in digital natives (born after 1980; Prensky, 2001). These findings offer new insights into sensorimotor representations of digital actions and intentions, expanding our understanding of embodied cognition in the touchscreen era. Moreover, this work contributes to the emerging framework of digital competence, a concept with potential applications in addressing digital exclusion.