Associative Learning and Memory in a Chimpanzee Fetus: Learning and Long-Lasting Memory before Birth

Nobuyuki Kawai, Seiichi Morokuma, Masaki Tomonaga, Naoki Horimoto, Masayuki Tanaka

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


We tested whether a chimpanzee fetus could form an association between an extrauterine tone and vibroacoustic stimulation (VAS) using classical conditioning treatment. Two kinds of pure tone were used as the conditioned stimuli, one where a 500-Hz tone was always followed by a VAS of 80 Hz (110 gal), the unconditioned stimulus (US), and another where a 1000-Hz tone was never followed by a VAS. This treatment was repeated 156 times in total until natural labor at 233 days of gestational age. Behavioral tests on the 33rd and 58th days after birth revealed a differential response to the tones: The infant displayed an exaggerated response to the 500-Hz tone, but not to the 1000-Hz tone. Other naïve chimpanzee infants did not show any response to either tone, which suggests that a chimpanzee fetus can distinguish between tones and form an association, and that it retains such information for at least 2 months after birth.

Original languageEnglish
Pages (from-to)116-122
Number of pages7
JournalDevelopmental Psychobiology
Issue number2
Publication statusPublished - 2004

All Science Journal Classification (ASJC) codes

  • Developmental and Educational Psychology
  • Developmental Neuroscience
  • Developmental Biology
  • Behavioral Neuroscience


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