Fig 1. The experimental set-up.

a) Photo of the arena set-up with one animal at the contact window (red circle). b) The contact window when closed and c) the open contact window. d) Schematic view of the arena with context regions as used for video scoring. The standard equipment for the experiments is colored in grey, the context regions that were used for video scoring are marked in different colors and inscribed with following abbreviations: CC = contact corners (dark blue); CR = contact region (light blue); CW = contact window (turquoise); F = food; FR = food region (green); H = red Plexiglas house; M = microphone, hanging from the top (see a); MB = male bedding (red); NR = neutral region (yellow); W = water.