Fig. 3. Crossing behaviour of crayfish recorded during 20 min of observation. (A) Mean frequency of crosses towards reflective and non-reflective (matte) walls. Group-socialized crayfish crossed towards reflective walls more than non-reflective walls. Dominant crayfish paired for 30 min and 3 days both crossed towards reflective walls more frequently. (B) The mean frequency of crosses away from reflective and non-reflective (matte) walls. Group-socialized crayfish crossed away from reflective walls more frequently than matte walls. After 30 min of pairing, both dominant and subordinate crayfish crossed away from reflective walls more than non-reflective walls. Dominant crayfish paired for 3 days also crossed away from reflective walls more frequently (paired t-test: ^**P<0.005, ^*P<0.05; N=25). Error bars depict standard deviation.