Page 71 - Encyclopedia of Philosophy of Language

1.3 Sherman and Austin
Beginning in 1975, two other chimpanzees, Sherman and Austin, were taught to use the lexigram keyboard in settings that emphasized communication between them. A clear requisite for competent communication between Sherman and Austin to be achieved was the ability to comprehend the meanings of lexigrams.
To cultivate comprehension, the chimpanzees learned that they both had to share specific information and to act upon that information. For example, prized foods and drinks (e.g., referents of lexigrams) were placed in sealed containers, hence not necessarily immediatelypresentanddirectlyobservable. Because, on any given trial, only one of the two chimpanzees saw, and hence knew, the specific food or drink that was placed in the container and because neither could receive the food unless both asked for it properly, the onus was upon the first chimpanzee to communicate the contents of the container to the second one. If the second chimpanzee comprehended the com- munication and properly requested the item which it had not seen, the food was shared between them. Otherwise, the palatable incentive was withheld. Thus, the need to communicate was instated. More impor- tantly, when their keyboard was taken away, the chim- panzees demonstrated that they had learned the importance of communication as well as how rep- resentational symbol systems work. This they dem- onstrated byinventingtheirownsymbolsystem.With no lexigrams available, they used manufacturers' brand names and labels (M&M, Coke, etc.) to tell one another the identity of the hidden food.
In these and a variety of other contexts, experiences served to encourage learning that the use of symbols enabled communication 'about' things, rather than that their use was just a ritual of responses necessary to access 'things.' Through many other additional communication paradigms that stressed the use of symbols to refer to things removed in space and time, Sherman and Austin became highly competent in labeling (i.e., naming) items, requesting items, com- plying with the requests of others, and most impor- tantly in understanding language symbols (see Savage- Rumbaugh 1986).
The communicative value of language for Sherman and Austin served to cultivate comprehension and generated other untaught, unanticipated uses of their word lexigrams. Sherman and Austin became the first chimpanzees to systematically communicate their wishes and desires to one another through the use of printed symbols. They learned to take turns, to exchange roles as speaker and listener, and to coor- dinate their communicating activities. Once they had learned the referential value of symbols, they began to use the keyboard to announce their intended actions: what it was they were going to do (e.g., tickle, chase, play-bite, or to set about getting a specific food or drink from a refrigerator in another room).
Sherman and Austin also demonstrated impressive symbol-based, cross-modal matching abilities (e.g., to equate the 'feel' of objects via touch to lexigrams and vice versa). Without specific training to do so, they were able to look at a lexigram symbol and then reach into a covered box and select the appropriate object on the basis of tactual cues alone. They could also feel or palpate an object not in view, and state the name of that object.
The most important demonstration that lexigrams were meaningful symbols to Sherman and Austin was achieved in a study where they, first, learned about the categories of 'food' and 'tool,' and then, second, appropriately classified lexigrams of their vocabu- laries using those categories.
Initially, only three foods and three tools were used to introduce the concept of 'categories' to them. Each chimpanzee was taught to label three edible items as 'foods' and three implements as 'tools.' They were then shown other food and implements to see if they could generalize the categorical concepts to things that had not been used during training. They could. Then they were shown the word-lexigram symbols for a variety of foods and implements and asked whether or not each word symbol (e.g., banana, straw, cheese, magnet, corn chips, etc.) stood for a food or a tool. They were able to label these word lexigrams as food- words or tool-words thefirst time they were asked and did so without specific training. Thus, they revealed an understanding of the fact that word symbols stood for things. They also knew the specific things each symbol stood for—otherwise they could not have called the word lexigram for 'corn,' a food and the word lexi- gram for '(drinking) straw,' a tool; for it was not the word lexigrams themselves that were food or tools, but rather the things they stood for that enabled them to categorize them correctly. Such skills left little doubt but that for Sherman and Austin their lexigrams served as representations of things not necessarily present and that they had mastered the essence of semantics (e.g., symbol or word meaning).
2. LaterStudieswithPanpaniscus
All of the chimpanzees discussed to this point were so-called 'common' chimpanzees of the genus and species, Pan troglodytes. There is a second major spec- ies of chimpanzee that has been erroneously called the 'pygmy' chimpanzee. It is now clear that this second species is not a pygmoid version of another form, and it is now by preference called the bonobo (Pan
paniscus).
Bonobos are even rarer and more endangered than the common chimpanzee and they more closely resemble humans. Bonobos frequently walk upright more readily and competently than P. troglodytes. Also, they use eye contact to initiate joint attention, iconic gestures to entice others to assume physical orientations and actions, and use vocal com-
Apes and Language
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