Fig 1. Experimental procedure.

Workers were collected from the colony and transferred, first to one of the manipulation-arenas (red arrows) for either social or isolated manipulation. Later, after a separation time (green arrows), these focal-workers were transferred to one half of the test-arena (red arrows). Before the test started, a retractable separation wall (W) divided the test-arena into two halves. Encounter-workers were transferred to the other half of the test-arena, and either workers from the same colony (NM; red arrows) or a different colony (NNM; blue arrows) were used. Video recording and test started by sliding out the separation wall.