  We show that sensorial delay alters the collective motion of self-propelling
agents with aligning interactions: In a two-dimensional Vicsek model, short
delays enhance the emergence of clusters and swarms, while long or negative
delays prevent their formation. In order to quantify this phenomenon, we
introduce a global clustering parameter based on the Voronoi tessellation,
which permits us to efficiently measure the formation of clusters. Thanks to
its simplicity, sensorial delay might already play a role in the organization
of living organisms and can provide a powerful tool to engineer and dynamically
tune the behavior of large ensembles of autonomous robots.
