Figure 1.

Experimental setup. The focal rat had access to a wooden stick (S) in the test phase of the experiment and could thereby move a tray (T) towards the partner or stooge that could then reach a food reward (R). The partner rat and stooge were put in a sealed Plexiglas box that was connected to an exhauster (E). (a) Set-up for experiments 1 and 2, where olfactory information was either provided or discarded from the partner in the neighbouring compartment. (b) Set-up for experiments 3 and 4, where the focal rat was provided with olfactory information from a partner rat that either helped a social partner or not in a different room, while the focal rat experienced the behaviour, but no olfactory information, of a stooge in the neighbouring compartment of its cage that never provided help.