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Three chimpanzees with a history of conditional and numeric token training spontaneously matched relations between relations under conditions of nondifferential reinforcement. Heretofore, this conceptual ability was demonstrated only in language-trained chimpanzees. The performance levels of the language-naive animals in this study, however, were equivalent(More)
We review the evidence for three important disparities involving the perception and judgment of identity relations by human and nonhuman primates. First, only humans beyond infancy and adult chimpanzees (Pan troglodytes) with a history of language or token training can explicitly judge relations (same or different) between relations (identity and(More)
Four infant chimpanzees learned a matching-to-sample task when only two training stimuli were used. They then spontaneously transferred the matching concept to novel items, including three-dimensional objects and fabric swatches, without any experimenter-provided differential feedback. These results support the view that the matching concept is broadly(More)
We used a familiarization-novelty procedure to determine whether 4 infant chimpanzees spontaneously perceive the sameness of and the difference between both concrete objects and relations between objects. In Experiment 1, a single object was presented on the Familiarization Trial 1 and the animal's looking time recorded. On the Test Trial 2, an object was(More)
After listening to a list of as many as six discriminably different 2-second sounds, a bottle-nosed dolphin classified a subsequent probe sound as either "old" (from the list) or "new." The probability of recognizing an old probe was close to 1.0 if it matched the most recent sound in the list and decreased sigmoidally for successively earlier list sounds.(More)
An experimenter induced tonic immobility (TI) in parentally naive chicks (G. gallusdomesticus). The chicks remained in TI longer when they were exposed to a conspecific adult fear squawk alarm call than when exposed to an equally novel attraction call or white noise. In a second experiment, both aerial-predator and ground-predator alarm calls enhanced TI(More)
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