As robots and virtual agents are increasingly envisioned as long-term companions, understanding how trust develops becomes crucial for ensuring safe and appropriate human-robot relationships. This research investigates how affective and cognitive trust evolve in social human-robot interactions. Participants (n=40) engaged in a 2 (social attitude: social, baseline) × 3 (time: t1, t2, t3) mixed-design user study with a social robot, using a novel Card Divination Task developed to elicit both cognitive and affective trust dimensions. Results show that cognitive trust develops early while affective trust emerges gradually. Moreover, social cues enhance both cognitive trust, affective trust, and participants' certainty in trust judgment. These findings provide empirical support for the theoretical distinction between trust dimensions and highlight the role of social behavior in shaping trust over repeated interactions.