Graduation Year



A variety of mammalian species use vocalizations to perceive the size of conspecifics. This ability may be an evolutionary adaptation shared by many mammalian species allowing them to detect the presence of a threat when visual resources are scarce or unavailable. Specifically, some mammals demonstrate prolonged attention to manipulated calls that suggest a larger conspecific compared to those suggesting a smaller conspecific. In humans this behavioral effect depends on the observer’s size—perceptions of ‘big’ or ‘small’ may differ between individuals. We explored whether this generalizes to other species by manipulating formant dispersion of dogs’ own barks to create synthetic barks that perceptually sounded either larger or smaller than the dog subject. We played these sounds to dogs and recorded how long they looked at the playback speaker. A univariate ANOVA revealed an effect of sound size (F(2,22) = 4.724, p = 0.020) such that dogs tended to look at the speaker longer in response to synthetic ‘larger’ dog sounds compared to synthetic ‘smaller’ sounds (Tukey post-hoc test, p = 0.053). Like humans, dogs may respond to novel barks by comparing the source's probable size to their own. We might expect to see this pattern of behavior in other mammalian species.