Kanzi and Mulika used a visual symbol system consiting of geometric symbols (Lexigrams) which brighten when touched. These symbols were on an electric keyboard. A speech synthesiser was added so that Kanzi comprehended words when the symbol was touched. Kanzi and Mulika used a pointing board, which is a thin laminated panel containing photo's of all the lexigrams. Kanzi and Mulika, would point to the lexigram whenever they wished to. The researchers would use spoken English when pointing to the lexigram. These gestures were spontaneous. Researchers also used ASL (American Sign Language) gestures and approximately 100 gestures were used and none of the researchers were fluent in ASL.
Differences in rearing environments:
- Kanzi and Mulika were born in captivity and spent time with their mother (Matata) as infants.
- Austin and Sherman were separated from their mother before being introduced to the language programme.
- Kanzi and Mulika weren't trained to use the Lexigram - they began to use it spontaneously.
- Austin and Sherman required formal training. However, later on they did acquire some symbols through observation
- Austin and Sherman didn't have a speech synthesiser because tests showed that unlike Kanzi and Mulika they didn't understand spoken English words