Fig. 9 in Early ant trajectories: spatial behaviour before behaviourism

Fig. 9 Detour paradigm as designed by Joseph Szymanski in 1911. The ants are deflected by a barrier (heavy black bar) from their habitual homebound course (vertical line at the left-hand side). The ants' corrective courses observed in two classic experiments are shown in green. Solid green arrow: wood ants, Formica rufa (Szymanski 1911), dashed green arrows: harvester ants, Messor barbarus (Santschi 1913a,b). Szymanski as well asCornetz and Santschiinterpreted these courses as the interactive result of forces 1 and 2. The red arrow depicts the eventual path integration (PI) vector pointing from the end of the barrier towards the goal (nest). However, in discussing the results of the detour experiment none of the early authors considered thePI option