Snapshots of computer simulation.

<p>Velocities of agents are displayed for two cases: a self-organized group and a group with one shill. The number of agents is in each case. Normal agents are represented by the little circle with red line pointing to the moving direction. (a) and (b) are for the self-organized case. (a) , , . agents are randomly distributed inside a square with . (b) After steps, the system reaches to a situation of several separated subgroups with different moving directions. So the group does not self-organize to a same heading -synchronization. (c) and (d) are for the case with a shill: (c) , a shill with is added into the same group as shown in (a). The shill is denoted as a dark little dot with blue arrow pointing to its heading direction. The blue circle centered at it indicates its neighborhood area (the radius is , which is the same as the radius of normal agents). (d) With the help of the shill using ‘consistent moving’ strategy, after 1999 steps, headings of all agents converge to a desired heading (zero), i.e., .