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We suggest that it is a disservice to psychology and to our understanding of the minds of chimpanzees (as well as other species) to hold any one individual or small group of individuals responsible as representatives for the entire species. This is especially nonproductive in the case of reports of negative performance in various tests of cognitive skill. We focus on the issue of why some chimpanzees may imitate whereas others do not. We focus also on the role of early rearing and individual differences that emerge from such rearing. Accounting for these differences and what may have caused them is crucial in truly understanding the chimpanzee mind.

As part of a program to explore the communicative abilities of bonobo apes within the human-ape culture at the Language Research Center at Georgia State University, we made two complementary analyses of a conversation between Sue Savage-Rumbaugh and Kanzi. We made both a conversation analysis and a lexico-grammatical analysis of their interaction. The conversation analysis revealed the participants negotiating the interpersonal meanings of confrontation and support, while the lexico-grammatical analysis revealed the ideational domain of the confrontation and support. Although many of the contributions of both participants did not fully express all the relevant meanings, both participants interpreted each other’s contributions in terms of their relevance to the patterns of interpersonal and ideational meanings being expressed in the conversation. We conclude that Kanzi’s considerable language abilities have been underestimated. First, Kanzi (despite his limited syntax) and Sue jointly construe a recognizable social world through discourse. Second, in exchanging discourse roles with Sue, Kanzi negotiates the asymmetrical power relation between himself and Sue. Finally, Kanzi’s accomplishment suggests that discourse semantics is a powerful motivation for the evolution of both interpersonal and ideational grammar.

Abstract: Primate research of the 20th century has established the validity of Darwin's postulation of psychological as well as biological continuity between humans and other primates, notably the great apes. Its data make clear that Descartes' view of animals as unfeeling “beast‐machines” is invalid and should be discarded. Traditional behavioristic frameworks — that emphasize the concepts of stimulus, response, and reinforcement and an “empty‐organism” psychology — are in need of major revisions. Revised frameworks should incorporate the fact that, in contrast to the lifeless databases of the “hard” sciences, the database of psychology entails properties novel to life and its attendant phenomena. The contributions of research this century, achieved by field and laboratory researchers from around the world, have been substantial — indeed revolutionary. It is time to celebrate the progress of our field, to anticipate its significance, and to emphasize conservation of primates in their natural habitats.

Beginning in May 1990, a long-term collaborative investigation between palaeolithic archaeologists and cognitive psychologists has focused upon the stone tool-making and tool-using abilities of a captive bonobo (Pan paniscus). To date, this bonobo (named Kanzi) has acquired the basic skills required to produce usable flakes and fragments by hard-hammer percussion (as well as by his own innovation of throwing), although his skills in flaking stone are not yet as well developed as those exhibited by the earliest known tool-making hominids of the Oldowan industry. This research strategy allows direct comparisons and contrasts to be made between the products of modern human stone tool-makers, prehistoric proto-human tool-makers and non-human primates that have not evolved a flaked stone technology in the wild. This enables us to investigate what possible cognitive and biomechanical conditions of pre-adaptation for lithic technology may be present in extant apes. The bonobo's stone tool-making abilities are compared to those evident among early hominids in order to understand the complexities of this derived behaviour pattern in the earliest stone tool-makers. The possible evolutionary implications of this study are discussed. Copyright 1993, 1999 Academic Press

Language comprehension in the great apes has been investigated through a variety of paradigms. This experiment employed a match-to-sample computer task to investigate the current language comprehension of three chimpanzees (Pan troglodytes) raised in different language environments but with a similar symbol system (lexigrams). Each of these animals still uses the lexigram keyboard system on a daily basis but none of the animals are the focus of ongoing ape language research programs. Six testing conditions were employed utilizing photographs, lexigrams and spoken English. The results indicated that all apes retained knowledge of at least some of the symbols that they had previously learned, and they each learned differing numbers of new lexigrams that were never taught to them. This indicates that rearing history is important not only in initial symbol acquisition in apes, but also in extended recall of the symbols, particularly when those symbols are used infrequently later in life. Differences in the current ages of these apes requires that such a conclusion be made tentatively, and suggests the need to continue the examination of symbol vocabulary size at various times throughout the life of each ape.

Los autores revisan la evidencia en favor de la capacidad de representación simbólica en simios, afirmando que todos los programas de lenguaje parten de la misma suposición: considerar signos, lexigramas y fichas de plástico como verdaderos elementos de vocabulario siempre que los simios sean capaces de ejecutar la etiqueta conductual correcta en presencia del correspondiente hecho u objeto. Consideran crucial el problema de la equivalencia entre capacidad de etiquetar y de representar simbólicamente y manifiestan que no se ha desarrollado ningún marco teórico dentro de la psicología animal que permita distinguir respuestas discriminativas condicionadas de respuestas simbólico-representacionales. Afirman que según sus investigaciones recientes la habilidad para utilizar símbolos de forma representativa puede ser alcanzada por chimpancés, pero no es posible deducir de la simple asociación entre etiqueta y objeto la existencia de esta función de representación o simbolización. También abordan la comunicación protolingüística de niños comparándola con la de chimpancés y desarrollan el concepto de verdadera simbolización, concluyendo que los estudios sobre el lenguaje de los simios han fracasado a la hora de obtener la verdadera simbolización en parte debido a que se han centrado casi exclusivamente en el aspecto de la producción, descuidando la competencia receptiva.