Informal Tests: Kanzi and Mulika were tested informally, in everyday situations. e.g. If Kanzi was playing with some keys, he may have been asked what they were. These tests weren't used as drills or rewards. These informal tests, only tested what lexigrams Kanzi and Mulika already knew.
Formal Tests: Kanzi and Mulika were also formally tested because on all their items in their vocab. These were done to check their responses weren't due to contextual cues or inadvertent glances. They were highly controlled e.g. the order of presentation and location of stimuli were carefully controlled in order to prevent any knowledge on the part of the experiment from inadvertently biasing the responses. No test item was ever repeated during a given session, an no 2 trials were ever the same.
4 formal tests:
- Match photo to the lexigram
- Match spoken word to the lexigram
- Match spoken word to photo
- Match synthesised words to lexigram
Similar tests were done on Austin and Sherman, however as they couldn't select photo's in response to English spoken words, they weren't tested on the photo's or the spoken English task as it was thought to be too difficult for them. Unlike Kanzi and Mulika, Austin and Sherman had to be rewarded with food to complete the tasks.