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Language comprehension in ape and child
Monographs of the Society for Research in Child Development
|January 1, 1993
Summary
This study compared language comprehension in a child and a bonobo, finding both understood novel sentences and syntactic structures. The bonobo excelled at recursion, while the child was better with conjunctions, suggesting shared cognitive foundations for language.
Area of Science:
- Comparative Psychology
- Linguistics
- Evolutionary Biology
Background:
- Human language acquisition research often prioritizes production over comprehension.
- Comprehension is increasingly recognized as preceding and guiding production in human language development.
- Previous research indicates some animal species can process speech sounds categorically, similar to humans.
Purpose of the Study:
- To systematically compare the language comprehension skills of a human child and a bonobo.
- To investigate whether non-human primates possess the cognitive capacity for understanding word-referent relations and syntactic structure.
- To challenge theories suggesting syntactic processing is uniquely human.
Main Methods:
- A 2-year-old child and an 8-year-old bonobo were raised in similar language-rich environments.
- Both subjects were exposed to spoken English and lexigrams from infancy via observational learning.
- Subjects responded to 660 novel sentences without prior training, with responses videotaped and scored for accuracy.
Main Results:
- Both the child and bonobo demonstrated comprehension of novel requests and simple syntactic devices.
- The bonobo showed higher accuracy in decoding word recursion compared to the child.
- The child outperformed the bonobo on conjunctive structures, likely due to short-term memory demands.
Conclusions:
- The findings suggest that the cognitive capacity for language comprehension may predate speech evolution in hominids.
- Syntactic processing abilities are not necessarily unique to humans, as evidenced by the bonobo's performance.
- The evolution of speech may be linked to physical adaptations like bipedalism and changes in the vocal tract, enabling categorical sound production.