Aim: To report on the language acquisition of Kanzi, a bonobo, and his younger sister Mulika.

The report covers a 17-month period, beginning when Kanzi was aged 2½ years.

To compare language acquisition in the bonobos with that of two common chimpanzees, Sherman and Austin, studied earlier (1975-1980).

Kanzi – a bonobo chimp(Pan paniscus)

Sherman & Austin –common chimps(Pan troglodytes)

Method: A CASE STUDY was carried out, focusing on one bonobo, Kanzi, but also including early data of his younger sister Mulika’s language acquisition.

Data were gathered by OBSERVATION and SELF-REPORT (computer)

The design was LONGITUDINAL, reporting over a 17-month period of Kanzi’s language acquisition.Think!What are the potential STRENGTHS and WEAKNESSES of the method chosen?- Can findings from a case study be generalised?- Are findings gained from observation reliable and valid?- Can all variables be controlled in a longitudinal study?

Subjects:

Kanzi – born in captivity in US (1980)

His mother was Matata, a wild- captured bonobo, who was the actual intended subject for the language study

Matata was not Kanzi’s biological mother. She had kidnapped him from his mother, Lorel, when he was just a few hours old

In 1983, Matata gave birth to Mulika, the second bonobo subject in this research

She grew up as Kanzi’s sister

Procedure:

The procedure is in 6 parts

1. Description of the environment where the apes were living

Naturalistic outdoor environment Indoor environment

•55 acre forest•Food placed in 17 locations – Kanzi + carers spent most of day collecting it•Kanzi communicated about food in the forest, and in a backpack, with lexigrams•Mulika also did this as she got older

•In the day, Kanzi and Mulika helped with domestic chores e.g. food preparation•Helped spontaneously with simple jobs like washing up•Watched videos of people/animals they knew from the centre•Played with toys•Played games e.g. tickle, chase…

Procedure:

The procedure is in 6 parts

2. The communication system used with the apes

The lexigram system:

•A visual symbol system•A keyboard of symbols, lit up when pressed•To start with Kanzi’s board had 8 lexigrams•By the end of the study, had 256 lexigrams•Connected to an electronic voice synthesiser – Kanzi understood spoken English•Indoors, the keyboards weren’t mobile – attached to computer•Outdoors, Kanzi used portable keyboards and laminated pointing boards

Other means of communication:•Spoken English•Gestures, including 100 ASL gestures

Procedure:

The procedure is in 6 parts

3. The exposure of Kanzi and Mulika to lexigrams – how they learned

The lexigram system

•Kansi was exposed to use of symbols, gestures, and human speech from age 6 months•This happened as he watched his mother, Matala, and her keepers•No-one tried to train Kanzi directly•Mulika learned from observing Kanzi

•They used the same lexigram system as Sherman and Austin•However, Sherman and Austin were taught to use it – Kanzi and Mulika weren’t. They spontaneously used it after observing others

Other differences between Kanzi and Mulika, and Sherman and Austin:•On Sherman and Austin’s keyboards there was no voice synthesiser – they didn’t understand human speech•Sherman and Austin didn’t use lexigrams outdoors – they couldn’t use them if they didn’t light up

Procedure:

The procedure is in 6 parts

4. Data recording and classifying

Classifying the utterances:

•INDOORS – lexigram use could be automatically recorded•OUTDOORS – a record was made by hand and entered into computer later•There was a complete record of Kanzi’s utterances from 30-47 months of age•For Mulika, the record ran from 11-21 months

The utterances were classified as:

• ‘correct’ or ‘incorrect’• ‘spontaneous’ if there was no prompting or

cueing• ‘imitated’ if they included a companion’s

utterance• ‘structured’ if they were in response to a

question

Structured questions were used to see if the chimps

could give a specific answer

Recording:

Procedure:

The procedure is in 6 parts

5. Vocabulary acquisition criteria

Establishing reliability:

•Utterance happened spontaneously, and could be verified on 9 out of 10 timese.g. if Kanzi indicated he wanted to go to the treehouse it would be verified if he took the experimenter to this location. This was counted as a ‘positive concordance score’

A 4½-hour block of real-time observations were compared with analysis of a video made at the

same time.• There was 100% agreement on the lexigrams

used and their correctness• There was disagreement on whether one

utterance was spontaneous• The video observer counted 9 extra utterances

What counted as ‘acquired’?

Procedure:

The procedure is in 6 parts

6. Formal testing of productive and receptive capacities

How?

•At the end of the study, Kanzi and Mulika were formally tested on all the words in their vocabulary. •Kanzi was tested in the 17th month of the study, aged 46-47 months•Mulika was tested aged 18-21 months

When?

Why?•To ensure that their performance was not due to the experimenters giving them cues, or inadvertent glances.

a) They were shown photographs and asked to select the right lexigram (+ vice versa)

b) They listened to a word or a synthesised version of the word and then asked to select the correct photograph or lexigram