Highly-instrumented particles (i.e. “Smart Rocks”) were included in monodisperse dry granular landslide experiments to quantify the collisional nature of such flows, and to investigate the influence of collisional flow on the mobility of landslides. The total number of particles comprising a constant source volume of 0.4 m3 was varied by filling the volume with monodisperse particles of nominal diameters of 3 mm, 6 mm, 13 mm, or 25 mm. Successively raising the total particle count resulted in flows that were increasingly thick relative to the respective particle size. Raw resultant acceleration data from the embedded smart rock sensors indicate that for each increase in grain size, there were increases in both the magnitude and frequency of particle collisions. Lidar-generated point clouds of the landslide deposits indicated that increases in mobility and spreading, compared using differences in travel angle, were directly proportional to increases in collisional activity. By changing the size of the landslide particles from 3 mm to 25 mm, the travel angle at the gravity centre (αg) was observed to decrease from 27.8° to 25.3° (Δαg = - 9.0 %) and the Fahrböschung angle (α) was observed to decrease from 25.0° to 21.4° (Δα = -14.4 %).