In this study I tested Benson Ginsburg's theory that dogs should show diminished ability, compared to wolves, in orienting in three-dimensional space and manipulating objects sequentially. Dogs of all ages and juvenile wolves should do poorly on these measures, but at some time before sexual maturity, the juvenile wolves should begin improving to the level of adult wolves. Two adult and seven juvenile wolves were compared with 40 adult German shepherds. The initial task was to pull a single rope suspended from the ceiling; complexity was increased by the addition of ropes and by changing spatial configurations. Adult wolf performance was consistently successful across all tests and requirements. Juvenile wolves had little difficulty with one and two rope tests, but did more poorly in the three rope tests. The behavior of the dogs grouped into four profiles (# of dogs): non-responders (6), one rope (15), two rope (14), and three rope responders (5).
Although a variety of experimental procedures have shown considerable evidence of "counting" in animals, there is no evidence of numerical competence when conspecifics are used as test stimuli. Here, we report evidence of a relative numerousness (2 vs. 4) judgment by rats that were required to discriminate the number of free-ranging conspecifics in an arena. This discrimination was ultimately disrupted by vigorous social interaction between the subjects and the to-becounted rats. Attempts to restrict the movement of object rats in Experiment 2 did not lead to reestablishment of the discrimination, although 2 animals did show evidence of a simple presence versus absence (0 vs. 5) discrimination, a precursor of numerical ability.Extensive research indicates that rats can use the numerical attribute of stimuli as a discriminative cue for performance in a variety of situations (Davis & Memmott,
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