Figure 1:

Depiction of conditioning paradigm. Animals underwent a 30-minute pre-test during which they could spend time on two novel beddings in opposite chambers. Animals were then housed overnight in their home cage before being placed in a novel, opaque cage and alternately housed on one bedding with their partner for 24 hours (study 1: randomly assigned paperchip or corncob bedding; study 2, corncob), then on the other bedding without their partner for 24 hours. After 6 alternating 24-hour conditioning periods, voles underwent a 30 minute post-test with the two beddings. In the control condition, voles were socially housed on both bedding types.