The person who answered this question is Blaine Cole, a researcher at the University of Houston in Texas who works with another species within the same genus of ant as that used at Bath. He filmed isolated ants and groups of various sizes, and then analysed the activity patterns of individual ants. Cole concluded that isolated individuals and individuals in sparsely populated groups have a pattern of activity-inactivity that is described as deterministic chaos. This is not a random pattern, but one which is so complex that it is impossible for an observer to predict what a particular ant will do next. Clearly, this must result from the way they interact.
Ants perceive their world primarily through their antennae.
They have, on the whole, very poor sight, whereas their antennae have exquisitely sensitive touch and smell receptors. When ants meet, they communicate via their antennae. Active ants may encounter either other active ants, or inactive ants. When the latter happens, the inactive ant is stimulated into action. Every 'ant' on the computerised grid has an activity-inactivity cycle that is chaotic.