Cognitive and Communicative Abilities of Grey Parrots

Grey parrots (Psittacus erithacus) solve various cognitive tasks and acquire and use English speech in ways that often resemble those of very young children. Given that the psittacine brain is organized very differently from that of mammals, these results have intriguing implications for the study and evolution of vocal learning, communication, and cognition. For 25 years, I have taught Grey parrots meaningful use of English speech (e.g., to label objects, colors, shapes, categories, quantities, and absence). Using this code, my oldest subject, Alex, exhibits cognitive capacities comparable to those of marine mammals, apes, and sometimes 4-year-old children (Pepperberg, 1999). Thus, his abilities are inferred not from operant tasks common in animal research, but from vocal responses to vocal questions; that is, he demonstrates intriguing communicative parallels with young humans, despite his evolutionary distance. I doubt I taught Alex and other parrots these abilities de novo; their achievements likely derive from existent cognitive and neurological architectures. My research therefore uses interspecies communication as an investigative tool to unveil avian communicative capacities and an avian perspective on the evolution of communication. SIGNIFICANCE OF INTERSPECIES COMMUNICATION Parrots’ vocal plasticity enables direct interspecies communication (Pepperberg, 1999). But why study their ability to use English rather than their natural system? The answer involves their existent cognitive architecture. I believe parrots acquire those elements of human communication that can be mapped or adapted to their own code. By observing what is or is not acquired, I uncover these elements and interpret the avian system. I believe parrots could not learn aspects of reference (e.g., labels for particular colors, object classes such as “apple”) unless their natural code had such referentiality. Although this manner of determining nonhuman referentiality is inferential, direct determination also has difficulties (see Cheney & Seyfarth, 1992). Moreover, pushing avian systems to see what input engenders exceptional learning (i.e., learning that does not necessarily occur during normal development—in this case, acquiring another species’ code) further elucidates learning processes: Because richer input is needed for a bird to learn another species’ code (allospecific acquisition) than for it to learn its own species’ code (conspecific learning) (Pepperberg, 1999), this line of research can show how and whether “nurture” modifies “nature” (e.g., alters innate predispositions toward conspecific learning), and thus uncover additional mechanisms for, and the extent of, communicative learning. Again, these mechanisms are likely part of existent cognitive architectures, not taught de novo. Interspecies communication also has practical applications. It is a tool that (a) directly states question content—animals need not determine both a query’s aim and the answer via trial and error; (b) exploits research showing that social animals may respond more readily and accurately within ecologically valid social contexts than in other situations; (c) facilitates data comparisons among species, including humans; (d) allows rigorous testing of the acquired communication code that avoids expectation cuing (i.e., subjects must choose responses from their entire repertoire; they cannot expect the answer to come from a subset of choices relevant only to the topic under question); and, most important, (e) is also an open, arbitrary, creative code with enormous signal variety, enabling animals to respond in novel, possibly innovative ways that demonstrate greater competence than operant paradigms’ required responses, and (f) thereby allows examination of the nature and extent of information animals perceive. Interspecies communication facilely demonstrates nonhumans’ inherent capacities and may enable complex learning (Pepperberg, 1999). HOW GREYS LEARN: PARALLELS WITH HUMANS My Greys’ learning sometimes parallels human processes, suggesting insights into how acquisition of complex communication may have evolved. Referential, contextually applicable (functional), and socially rich input allows parrots, like young children, to acquire communication skills effectively (Pepperberg, 1999). Reference is an utterance’s meaning—the relationship between labels and objects to which they refer. Thus, in my research, utterances have reference because the birds are rewarded by being given the objects they label. Context (function) involves the situation in which an utterance is used and effects of its use. The utterances also are functional because they initially are used—and responded to—as requests; this initial use of labels as requests gives birds a reason to learn sounds constituting English labels. Social interaction, which is integral to the research, accents environmental components, emphasizes common attributes—and possible underlying rules—of diverse actions, and allows continuous adjustment of input to learners’ levels. Interaction engages subjects directly, provides contextual explanations for actions, and demonstrates actions’ consequences. In this section, I describe the primary training technique, then experiments my students and I have conducted to determine which input elements are necessary and sufficient to engender learning. Model/Rival Training My model/rival (M/R) training system (background in Pepperberg, 1999) uses three-way social interactions among two humans and a parrot to demonstrate targeted vocal behavior. The parrot observes two humans handling one or more objects, then watches the humans interact: The trainer presents, and queries the human model about, the item (or multiple items) (e.g., “What’s here?” “What color?”) and praises the model and gives him or her the object (or objects) as a referential reward for answers that are correct. Incorrect responses (like the bird may make) are punished by scolding and temporarily removing the item (or items) from sight. Thus, the second human is a model for the parrot’s responses, is its rival for the trainer’s attention, and also illustrates the consequences of making an error: The model is asked to try again or talk more clearly if the response was (deliberately) incorrect or garbled, so the method demonstrates corrective feedback. The bird is also queried and initially rewarded for approximations to “correct” responses. As training progresses, the criteria for what constitutes a correct response become increasingly strict; thus, training is adjusted to the parrot’s level. Unlike other laboratories’ M/R procedures (see Pepperberg, 1999), ours interchanges the roles of trainer and model, and includes the parrot in interactions, to emphasize that one being is not always the questioner and the other the respondent, and that the procedure can effect environmental change. Role reversal also counteracts an earlier methodological problem: Birds whose trainers always maintained their respective roles responded only to the human questioner. Our birds, however, respond to, interact with, and learn from all humans. M/R training exclusively uses intrinsic reinforcers: To ensure the closest possible correlations of labels or concepts to be learned with their appropriate referents, we reward a bird for uttering “X” by giving the bird X (i.e., the object to which the label or concept refers). Earlier unsuccessful programs for teaching birds to communicate with humans used extrinsic rewards (Pepperberg, 1999): The reward was one food that neither related to, nor varied with, the label or concept being taught. Use of extrinsic rewards delays label and concept acquisition because it confounds the label of the targeted exemplar or concept with that of the food. My birds never receive extrinsic rewards. Because Alex sometimes fails to focus on targeted objects, we trained him to say, “I want X” (i.e., to separate labeling and requesting; see Pepperberg, 1999), in order to request the reward he wants. That is, if he identifies something correctly, his reward can be the right to request something more desirable than what he has identified. This procedure provides flexibility but maintains referentiality. Thus, to receive X after identifying Y, Alex must state, “I want X,” and trainers will not comply until the original identification task involving Y is completed. His labels therefore are true identifiers, not merely emotional requests. Adding “want” provides additional advantages: First, trainers can distinguish incorrect labeling from appeals for other items, particularly during testing, when birds unable to use “want” might misidentify objects not because they do not know the correct label but because they are asking for treats, and their performance might reflect a lack of accuracy unrelated to their actual competence. Second, birds may demonstrate low-level intentionality: Alex rarely accepts substitutes when requesting X, and continues his demands (see Pepperberg, 1999), thus showing that he truly intends to obtain X when he says “want X.” Eliminating Aspects of Input M/R training with Alex successfully demonstrated that reference, functionality, and social interaction during training enabled label and concept acquisition, but not which or how many of these elements were necessary, sufficient, or both. What would happen if some of these elements were lacking from the input? Answering that question required training and testing additional parrots, because Alex might cease learning after a change in training merely because there was a change, not necessarily because of the type of change. With 3 new naive Greys—Kyaaro, Alo, and Griffin—students and I performed seven sets of experiments (see Pepperberg, 1999; Pepperberg, Sandefer, Noel, & Ellsworth, 2000) to test the relative importance of reference, functionality, and social interaction in training. In the first set of experiments, we compared simultan