Abstract
I summarized our recent studies, which assessed chimpanzees' symbolic representation of sequence. Chimpanzees have demonstrated their capacities to integrate fractal information about pairs of stimuli into an ordered series by showing transitive inference. Language is not a necessary prerequisite for using transitive inference. But the concept of number may promote understanding of ordered sequence. A chimpanzee trained in ordinality demonstrated a perfect transitivity. Transitivity is frequently used for the assessment of implicit ordinal number comprehension in human infant. Symbolic distance effects were obtained in a numerical ordering task by the chimpanzee, named Ai, which suggests that the chimpanzee perform the task by making reference to a linear representation of number order. Also in this task, the chimpanzee first explore the number space, calculating the ordinal relationships and spatial locations of each number, and then used this stored information to guide her subsequent responses. These strategies were highly similar to that of expected to be used by humans but not by macaque monkeys.
