Abstract # 2265 Event # 31:

Scheduled for Thursday, June 21, 2007 01:15 PM-01:30 PM: Session 6 (North Main Hall F/G) Oral Presentation

Speech Sound Discrimination Ability in a Lowland Gorilla

C. Nunes, M. Goodreau, C. Tam and F. Patterson
The Gorilla Foundation, 1733 Woodside Road, Suite 330, Redwood City, CA 94061, USA
     A captive female lowland gorilla's (Gorilla gorilla gorilla) ability to discriminate receptively American English phonemes within sets of minimal contrasts was tested when she was 15 years old. As a subject in a longitudinal language acquisition project, this gorilla (Koko) communicates using sign language, which she learned through the simultaneous communication of spoken English and American Sign Language (ASL). She was presented with pictures representing words taken from her vocabulary (55 sets of 2, 3, or 4) that differed by one phoneme, either vowel or consonant, in the initial, medial, or final positions. For example, these test items were among those included: honey/money/bunny/funny, boat/bite, worm/word/work. Koko was asked vocally to "Show me ____" or "Give me the ____." Koko was able to discriminate phonemes in a linguistic context (78.2% correct). A goodness-of-fit analysis indicated that Koko's responses were significantly better than chance [c2(2)=48.53, p<0.001]. Koko's scores were best when tested for final word sounds (100%) and when offered 4 words per test item (90%). Her poorest performance was with medial consonant word sounds when offered only 2 words per item (55.6%). These results suggest that motivational as well as perceptual factors may have played a role in test performance. Nevertheless this finding indicates phoneme discrimination ability in a gorilla and supports the theory that speech perception evolutionarily preceded speech production.