Figure 5. Activation within caudate ROIs in dogs with low and high aggressivity (relative to our sample mean) for reward and no-reward signals across the three source conditions.

Values and s.e. are derived from the full mixed-effects model, using Z-scores for C-BARQ factor 1 of + 1 for dogs with higher aggressivity and −1 for dogs with lower aggressivity (±1 corresponded to the upper and lower limits of the scores). Dogs with lower aggressivity showed significantly greater caudate activation to reward versus no reward signals presented by their familiar handler (p < 0.001), but not from unfamiliar humans (p = 0.15) or computers (p = 0.09), while dogs with higher aggressivity showed significantly greater activation to the reward versus no reward signals from the unfamiliar human (p = 0.003) and computer (p < 0.001), but not their familiar handler (p = 0.07).