Social Stimulation by the Owner Increases Dogs’ (Canis familiaris) Social Susceptibility in a Food Choice Task—The Possible Effect of Endogenous Oxytocin Release

Abstract

Recent evidence suggests a human-like susceptibility to social influence in dogs. For example, dogs tend to ignore their ‘natural’ preference for the larger amount of food after having seen a human’s explicit preference for a smaller quantity. However, it is still unclear whether this tendency to conform to the partner’s behaviour can be influenced by social stimuli and/or the neurohormone oxytocin as primers to prosocial predispositions. In Experiment I, eighty two dogs were tested using Prato-Previde et al.’s food quantity preference task. In Experiment I, we investigated in a 2 × 2 design how (i) a 10-minute-long social stimulation by the owner versus a socially ignoring pre-treatment as well as (ii) on-line ostensive communications versus no communication during task demonstration affect dogs’ (N = 82) choices in the abovementioned food choice task. Results indicate that the owners’ pre-treatment with social stimuli (eye contact, petting) increased dogs’ susceptibility to the experimenter’s food preference, but the salient ostensive addressing signals accompanying human demonstration masked this social priming effect. In Experiment II, N = 32 dogs from the subjects of Experiment I were retested after oxytocin (OT) or placebo (PL) pre-treatments. This experiment aimed to study whether intranasal administration of oxytocin as compared to placebo treatment would similarly increase dogs’ tendency to re-enact the human demonstrator’s counterproductive choice in the same task. Results showed an increased susceptibility to the human preference in the OT group, suggesting that both socially stimulating pre-treatment and the intranasal administration of oxytocin have similar priming effects on dogs’ social susceptibility.

Dogs’ social susceptibility is differentially affected by various dog–Human interactions. A study on family dogs, former shelter dogs and therapy dogs

“…For visual comparison, the “change in bias” scores of dogs adopted from a shelter, therapy dogs and pet dogs from both the current and our previous study [ 10 ] are provided in Table 1 . for the available pre-treatment conditions.…”

“…Previous research has shown that social priming (i.e. social stimulation provided by the owner) has the potential to increase pet dogs’ social susceptibility in a similar way as would an intranasal oxytocin treatment [ 10 ]. It has been also shown that the oxytocin-increasing effect of social interactions depends on the relationship between the interacting partners [ 23 ].…”

“…This differential effect is further modulated by the previous life history of dogs, as evidenced by our results on therapy dogs and former shelter dogs. While we do have some indication [ 10 , 11 ], that the behavioural changes observed are at least partly modulated by the neuro-hormone oxytocin, further research should look into the exact mechanisms modulating these processes.…”

“…A 10-minute long social interaction with the owner, in contrast to a socially ignoring pre-treatment (owner present, but ignoring the dog), increased the number of counterproductive choices in the human influence compared to the baseline trials. This effect is most likely driven by dogs’ endogenous oxytocin increase, as the social stimulation versus ignoring results paralleled the effect of intranasal oxytocin (contrasted to placebo) administration [ 10 ]. There is also independent physiological evidence showing elevated oxytocin levels after the social treatment used in that study [ 11 ].…”

“…The above cited food choice study [ 10 ] showing an effect of positive social interaction on social susceptibility has used the owner as the interacting partner. Here in Study 1. we aim to replicate those conditions (social interaction with the owner and social ignoring) and complement them with a condition using social interaction with a stranger.…”