Positive intonation increases the perceived value of smaller rewards in a quantity discrimination task with dogs (Canis familiaris).

Like many other species, dogs have a natural quantity judgment system to assist with decision making to maximize resources. Additionally, dogs are highly sensitive to, and influenced by, human-delivered ostensive (i.e., social) cues. Here, we assessed the influence of one such cue-a high, rising, positive "Oooh!" sound-on dogs' choice of differing quantities of pieces of food presented on two different plates. Subjects (N = 29) received 16 randomized trials of four conditions: 1 versus 1 paired with experimenter "Oooh!" while looking at the one plate, 1 versus 3, 3 versus 1 paired with experimenter "Oooh!," and 1 versus 1. As predicted, dogs chose the larger quantity more often in 1 versus 3 conditions. Contrary to one of our predictions, subjects chose the 1 versus 1+ "Oooh!" at chance levels. However, in support of another prediction, pairing the smaller reward with a positive intonation in 3 versus 1+ "Oooh!" significantly reduced dogs' choice of the larger reward. That is to say, without the presence of words, eye contact, or facial expressions, dogs followed a misguiding cue and chose a smaller reward that a stranger had deemed more valuable than a larger one. Local enhancement as well as a drive to increase social capital with the human are discussed as possible explanations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).