Three dogs stiffened when they saw the fake dog but not the real dog and three dogs stiffened when they saw the real dog but not the fake dog. Only one dog (2%) of 45 stiffened when it saw both the fake and real dogs, leading to a very low positive agreement (25%). Since some behaviors were rarely or very frequently observed, the Prevalence-Adjusted, Bias-Adjusted Kappa (PABAK) coefficient was calculated for each behavior variable