Spontaneous Symbol
Acquisition and Communicative
Use by Pigmy Chimpanzees
(Pan paniscus)
Savage-Rumbaugh, McDonald,
Sevcik, Hopkins and Rubert (1986).
Abstract
• Pygmy chimps are used (Pan paniscus)
• 2 chimps that have learnt language from
other chimps.
• Can produce agent-verb-recipient
combinations.
• Common chimpanzees (Pan troglodytes) are
unable to do this. Use simple verbs only
referring to the addressee.
What’s in a name?
• Associational learning – symbol enables the
acquisition of a particular object.
• Representational learning – comes after
associational learning and means that the
ape can label objects and refer to objects
that are not present.
Understanding Spoken English
Words
• Disappointing results from previous
research.
Language Learning without
Training
• Research based on Pygmy chimps Kanzi
mainly and younger half-sister Mulika.
• They are highly social animals and thus are
more likely to have a predisposition for
acquiring language.
Subjects
• Pan Paniscus – reared with access to
mother. Kanzi 4 years old male, born in
captivity whereas mother (Mutata) was
caught in the wild. Started learning at 6
months. Also Mulika the younger half-sister
who was attached to humans.
Subjects
• Pan Troglodytes – reared with language
between 1975 to 1983. Austin and Sherman.
They started language training at 1½ and
2½ years respectively.
Communication System
• Lexigram board – computer with voice
synthesiser, but pointing board was used in
the field owing to the computer board not
being robust enough.
• 100 ASL (American Sign Language) signs
were also used.
• The pointing boards were not so good for
use by the Pan troglodytes as they use broad
hand movements.
Early Rearing and Exposure to
Lexigrams
• Matata (mother) was trained whilst she was
looking after Kanzi. Kanzi was not trained
at this time but could observe his mother
training. Kanzi often interrupted. At 1½
years Kanzi showed an interest in the
keyboard, randomly pressing keys to obtain
food.
• Mulika (younger sister of Kanzi) did not
observe her mother training but did observe
Kanzi.
Rearing and exposure to Lexigrams
following separation from Matata (Mother).
• The Pygmy chimps Kanzi and Mulika were
trained in a similar way to the Common
Chimpanzees Sherman and Austin, except
that the common chimps could not use a
portable keyboard and they did not
understand human speech, so tones were
used every time a symbol was pressed.
Kanzi and Mulika had synthesised speech
on their keyboards.
Rearing and exposure to Lexigrams
following separation from Matata (Mother).
• Kanzi and Mulika did not have formal
training because:
– A) they began using symbols without training.
– B) They identified symbols regardless of the
position on the board.
– C) They did not confuse symbols for similar
items.
– D) They understood spoken English.
Naturalistic Outdoor
Environment
• Kanzi and Mulika were trained to collect
food from locations around a wood. Started
training with pictures of food. Kanzi could
select the picture that represented the food
that he wanted to travel to. Upon retrieval
the chimps were given the opportunity to
carry their food in a backpack if they
responded positively to the question.
Naturalistic Outdoor
Environment
• If Kanzi chose a food that was already in his
backpack he was then asked whether or not
he wanted to eat the food in the backpack or
travel to the location where the food was
stored.
• After 4 months of training Kanzi (aged 3
years) was able to lead a ‘blind’
experimenter to the correct locations of
chosen foods.
Indoor environment
• Kanzi and Mulika, like Austin and Sherman
join in household chores and enjoy
entertainments including specially prepared
videos with lexigram subtitles.
Data Recording
• Records for Kanzi from 2½ years old until
17 months after that. Symbol use was
automatically recorded indoors, but
researchers took notes when outdoors with
the portable lexigram board. Mulika was
studied from 11 until 21 months. Utterances
were recorded as spontaneous, imitated or
structured (which means replies to questions
from the researchers).
Vocabulary acquisition criteria
• A lexigram was said to have been learnt if it
occurs nine times out of 10 spontaneously
and was verified (concordance between sign
and behaviour). A sign could be dropped
from the chimp’s vocabulary if it was not
used correctly 90% of the time.
Vocabulary acquisition criteria
• Four and a half hours of videotape was
checked by an independent observer. The
original observer (real-time observer) was
not aware of the checking procedure. There
was 100% agreement. Nine utterances were
noted by the independent video observer
that were not noticed by the real-time
observer. This suggests that many signs are
missed in real-time.
Tests of productive and receptive
capacities.
• Tested informally in everyday situations. At
the end of 17 months Kanzi was tested
under control blind lab conditions. The
testing took place in the afternoon with
between 20 and 14 trials in one session.
Three or four alternatives were used.
Alternatives were not used on consecutive
trials. All of the alternatives were selected
from targets.
Tests.
• Photograph to lexigram- shown a
photograph and have to choose one of three
lexigrams. The alternatives were selected by
a second blind experiment and the choice
was not observed by the original observer
(behind a folding blind).
• Spoken English to photograph- “Kanzi,
can you show me X?”
Tests.
• Spoken English to lexigram
• Synthesised speech to lexigram- as a
control for intonation. The word was
sounded twice and 4 lexigrams were
presented.
• Sherman and Austin were tested on their
vocabularies without the spoken English
tests. They were rewarded with food unlike
Kanzi and Mulika.
Untutored gestural usage: some
observations.
• Between 6 and 16 months Kanzi and
Mulika used iconic gestures for travel and
actions. For example pointing, twisting for
undoing lids, cracking nut gestures, blowing
up a balloon. These were often
accompanied by affective vocalisations.
Untutored gestural usage: some
observations.
• Sherman and Austin only used gestures
when being given full human attention, and
would not persist. They did not elaborate or
give specific gestures but just generally
pointed.
First appearance of lexigram usage
for communicative purposes.
• After a separation from the mother Kanzi’s
use of the keyboard was less random and
more purposeful. Could indicate particular
foods, or ball to play with.
First appearance of lexigram usage
for communicative purposes.
• Mulika began to show signs at 12 months.
Tended to use “milk” for a variety of
activities. After two months symbols began
to be selected more appropriately. After
“milk” the second symbol was “surprise”
which indicated a randomly selected
reward. Kanzi learnt the symbol
“strawberries” whilst eating mushrooms and
at first only used this symbol in this context.
Progress during the 17 months after
the initial separation from Matata.
• Kanzi
• 7 words at 30 months. 44 words at 46
months (productive) (over 50 receptive) but
5 words dropped out of use. Combinations
at 46 months were approximately 800.
Kanzi’s receptive mode higher than
productive mode. 80% were spontaneous.
Progress during the 17 months after
the initial separation from Matata.
• Mulika
• “milk” at 17 months. Six words at 22
months.
• Kanzi’s keyboard grew as the vocabulary
grew, whereas Mulika had to contend with a
large keyboard from the start.
Combinations
• 6% of utterances. Produced combinations
without repetition, such as “ice water go”
meaning get some ice water, rather than
“play me Nim play” (Terrace et al 1979).
Kanzi produced 2,540 utterances compared
to 19,000 for Nim. Kanzi used
combinations for games or to benefit others,
whereas Nim’s combinations were for food
for himself only.
Combinations
• Kanzi invented combinations that asked
researchers to chase each other, which was
not demonstrated in advance.
The issue of imitation.
• Kanzi and Mulika’s utterances were truly
spontaneous whereas Sherman and Austin’s
were often prompted by some activity of the
researcher (e.g. placing food).
Formal tests.
• Kanzi and Mulika understood the abstract
nature of these tests. No rewards or activity
would follow the choice. Sherman and
Austin expected to be rewarded according
to their choice.
Formal tests.
• Sherman and Austin were unable to do the
Spoken English tests and would show signs
of frustration (scratching all over their
bodies). They would instead attempt to
mimic spoken English unsuccessfully.
Formal tests.
• As a control for the possibility that Kanzi
might be responding to voice intonation he
was tested on a Votrax speech synthesizer.
Each symbol was presented three times and
was paired with two alternatives. Kanzi did
well on this task.
Announcement and Verification
of Travel Plans.
• Kanzi learned the location of 17 food sites
within 4 months.
• During a blind test of Kanzi’s knowledge of
the foraging sites, he selected a photograph,
a lexicon or both. Each time he then led the
experimenter to the correct location. On
nearly all of the trials, Kanzi took the most
direct route possible.
General observations regarding
Kanzi and Mulika’s symbol usage.
• Kanzi mainly and to an extent Mulika
generalise their symbols to other related
objects. For example ‘coke’ is generalised
to all dark fizzy drinks or ‘rain’ is used to
refer to water from a garden sprinkler.
Kanzi sometimes uses the food names to
indicate where he wants to go in the woods.
Discussion
• It is recognised that the sample size of 2
pygmy chimps and 2 common chimps is
small. Also the environments were different
for the two pairs of chimps. Nonetheless it
was felt that the empirical evidence was so
strong as to discount these possible
confounding variables.
• 4 discussion points follow.
Discussion
• 1. Kanzi and Mulika learnt rapidly whereas
Austin and Sherman needed a lot of
coaching. Kanzi and Mulika spontaneously
recognised that lexigrams can stand for
objects and events. They did not need to
differentiate between naming and requesting
and their receptive skills preceded their
productive skills (they understood words
before they used them).
Discussion
• 2. Kanzi and Mulika understand spoken
English whereas Austin and Sherman do
not, they relied more on pointing to indicate
which object was to be retrieved, for
example. Also Kanzi and Mulika did not
require strong contextual clues.
Discussion
• 3. Kanzi and Mulika could be more precise
with their symbols. Austin and Sherman
would confuse ‘juice’ and ‘coke’ and could
only handle broad definitions, whereas
Kanzi and Mulika readily differentiated
between lexigrams for similar items.
Discussion
• 4. Kanzi could ask for A to act on B, where
neither A nor B was Kanzi, whereas Austin
and Sherman could only form requests that
involved themselves.
Conclusion
• Assuming that Kanzi and Mulika are
representative of typical pygmy chimps it is
concluded that pygmy chimps have a far
greater propensity for the acquisition of
symbols than other apes.
The End