Figure 2.

Mean time spent in the compartment with images of either pain or neutral expressions of conspecifics. In the original condition, rats stayed longer in the compartment with images of neutral expressions than in that with pain expressions. In the three airbrushed image conditions and shuffled image condition, there were no differences in the time spent in the compartments with the images of pain expressions and neutral expressions. Black bars indicate averaged staying time for pain expression; white bars indicate averaged staying time for neutral expression. Error bars represent s.e.m. ^**p<0.01.