Increasing arousal enhances inhibitory control in calm but not excitable dogs

Abstract

The emotional-reactivity hypothesis proposes that problem-solving abilities can be constrained by temperament, within and across species. One way to test this hypothesis is with the predictions of the Yerkes-Dodson law. The law posits that arousal level, a component of temperament, affects problem solving in an inverted U-shaped relationship: Optimal performance is reached at intermediate levels of arousal and impeded by high and low levels. Thus, a powerful test of the emotional-reactivity hypothesis is to compare cognitive performance in dog populations that have been bred and trained based in part on their arousal levels. We therefore compared a group of pet dogs to a group of assistance dogs bred and trained for low arousal (N = 106) on a task of inhibitory control involving a detour response. Consistent with the Yerkes-Dodson law, assistance dogs, which began the test with lower levels of baseline arousal, showed improvements when arousal was artificially increased. In contrast, pet dogs, which began the test with higher levels of baseline arousal, were negatively affected when their arousal was increased. Furthermore, the dogs' baseline levels of arousal, as measured in their rate of tail wagging, differed by population in the expected directions. Low-arousal assistance dogs showed the most inhibition in a detour task when humans eagerly encouraged them, while more highly aroused pet dogs performed worst on the same task with strong encouragement. Our findings support the hypothesis that selection on temperament can have important implications for cognitive performance.

Keywords: Arousal; Assistance dogs; Canine; Cognition; Inhibitory control.

Fig. 1

The predictions of the Yerkes-Dodson hypothesis. For a simple task, it posits a positive linear relationship between arousal level and task performance. For a complex task, it posits an inverted U-shaped relationship, wherein increasing arousal level is linked to stronger performance only up to a certain point, after which increasing arousal harms performance

Fig. 2

(A) Curtain apparatus from the dog’s perspective (B) The position of the experimenter while calling the dog behind the curtain apparatus during both low arousal and high arousal trials

Fig. 3

(A) Performance of assistance dogs on the detour arousal task by trial number and trial type. The lines represent the mean composite response score (touch + pathway + time to success), which is an inhibitory control failure index in which higher scores correspond to longer and less efficient problem solving. The gray line indicates dogs (n=46) who experienced order A, High Arousal First (5 high arousal detour trials followed by 5 low arousal detour trials), while the black line indicates dogs (n = 30) who experienced order B, Low Arousal First (5 low arousal detour trials followed by 5 high arousal detour trials); (B) Performance of pet dogs on the detour arousal task by trial number and trial type. The gray line indicates dogs (n=15) who experienced order A, High Arousal First, while the black line indicates dogs (n=15) who experienced order B, Low Arousal First

Fig. 4

(A) Cumulative performance of assistance (n=76) and pet (n=30) dogs during low arousal and high arousal trials. The bars represent the mean composite response score (touch + pathway + time to success), which is an inhibitory control failure index in which higher scores correspond to longer and less efficient problem solving. The interaction between trial type and dog type is significant (p < 0.001), with assistance dogs exhibiting optimal levels of inhibitory control during high arousal trials and pet dogs exhibiting optimal levels during low arousal trials; (B) Cumulative performance of assistance (n=76) and pet (n=30) dogs over the entire task, divided into groups based on those that completed high arousal trials first and those that completed low arousal trials first. The bars represent the same as in part (A). The interaction between order and dog type is significant, with assistance dogs that completed high arousal trials first exhibiting optimal levels of inhibitory control on the task overall and pet dogs that completed low arousal trials first exhibiting optimal levels of inhibitory control on the task overall (p < 0.01)

Fig. 5

Average performance of dogs in the 1^st quintile of baseline arousal (n=23), 3^rd quintile of baseline arousal (n=21), and 5^th quintile of baseline arousal (n=22). Baseline arousal was determined by tail-wagging rate during the familiarization walk-around, prior to the start of testing. Performance is shown as a difference score, acquired by taking the mean composite response score (touch + pathway + time to success) for high arousal trials and subtracting the mean composite response score for low arousal trials. Negative scores correspond to better performance under high arousal conditions, scores close to zero correspond to no strong difference between conditions, and positive scores correspond to better performance under low arousal conditions.