Irene M. Pepperberg

Insightful string-pulling in Grey parrots (Psittacus erithacus) is affected by vocal competence.

Four Grey parrots (Psittacus erithacus) were tested on their ability to obtain an item suspended from a string such that mutiple, repeated, coordinated beak–foot actions were required for success (e.g., Heinrich 1995). Those birds with little training in referential English requests (e.g. “I want X”) succeeded, whereas birds who could request the suspended item failed to obtain the object but engaged in repeated requesting.

In Search of King Solomon’s Ring: Cognitive and Communicative Studies of Grey Parrots (Psittacus erithacus)

During the past 24 years, I have used a modeling technique (M/R procedure) to train Grey parrots to use an allospecific code (English speech) referentially; I then use the code to test their cognitive abilities. The oldest bird, Alex, labels more than 50 different objects, 7 colors, 5 shapes, quantities to 6, 3 categories (color, shape, material) and uses ‘no’, ‘come here’, wanna go X’ and ‘want Y’ (X and Y are appropriate location or item labels). He combines labels to identify, request, comment upon or refuse more than 100 items and to alter his environment. He processes queries to judge category, relative size, quantity, presence or absence of similarity/difference in attributes, and show label comprehension. He semantically separates labeling from requesting. He thus exhibits capacities once presumed limited to humans or nonhuman primates. Studies on this and other Greys show that parrots given training that lacks some aspect of input present in M/R protocols (reference, functionality, social interaction) fail to acquire referential English speech. Examining how input affects the extent to which parrots acquire an allospecific code may elucidate mechanisms of other forms of exceptional learning: learning unlikely in the normal course of development but that can occur under certain conditions.

The value of the Piagetian framework for comparative cognitive studies

Abstract. Although the Piagetian framework has been used by numerous researchers to compare cognitive abilities of diverse species, the system is often criticized as implemented. I examine the various criticisms, suggest ways in which the system can be improved, and argue for the need for descriptive systems such as the Piagetian framework to complement programs that look for cellular and molecular bases or mathematical models to explain behavior.

Simultaneous development of vocal and physical object combinations by a Grey parrot (Psittacus erithacus): bottle caps, lids, and labels.

On the basis of primarily behavioral data, researchers (e.g., P. M. Greenfield, 1991) have argued (a) that parallel development of communicative and physical object (manual) combinatorial abilities exists in young children; (b) that these abilities initially have a common neural substrate; (c) that a homologous substrate in great apes allows for similar, if limited, parallel development of these 2 abilities; and (d) that such abilities thus may indicate a shared evolutionary history for both communicative and physical behavior (J. Johnson-Pynn, D. M. Fragaszy, E. M. Hirsh, K. E. Brakke, & P. M. Greenfield, 1999). The authors of the present study found a comparable, if limited, parallel combinatorial development in a Grey parrot (Psittacus erithacus). Given the evolutionary distance between parrots and primates, the authors suggest that the search for and arguments concerning responsible substrates and common behavior should be approached with care and should not be restricted to the primate line.

Evidence for a form of mutual exclusivity during label acquisition by grey parrots (Psittacus erithacus)

The authors present context-dependent evidence for a form of mutual exclusivity during label learning by Grey parrots (Psittacus erithacus). For human children, mutual exclusivity refers to their assumption during early word learning that an object has one and only one label. Along with the whole-object assumption (that a label likely refers to an entire object rather than some partial aspect), mutual exclusivity is thought to guide children in initial label acquisition. It may also help children overcome the whole-object assumption by helping them interpret a novel word as something other than an object label, but for young children, any second label for an object can initially be more difficult to acquire than the first. The authors show that Grey parrots quickly learn object labels for items, then have considerable difficulty learning to use color labels with respect to a previously labeled item unless specifically taught to use a color and object label as a pair.

Vocal learning in the Grey parrot (Psittacus erithacus): effects of species identity and number of trainers.

Grey parrots (Psittacus erithacus) learn referential English labels when they view and interact with 2 humans who model vocal labeling and who demonstrate referentiality and functionality of a label (I.M. Pepperberg, 1990a). To test if both trainers are necessary, the authors contrasted 2-trainer modeling with training by 1 human who presented targeted labels to a bird in concert with appropriate items, who asked questions, and who would reward attempts at the label with the item. The bird was also tutored by either 1 or 2 interactive humans in conjunction with a conspecific who already used referential labels. Referential labels were learned from multiple live tutors but not a single trainer. Presence of a conspecific enhanced learning compared with single-trainer sessions but did not affect acquisition in 2-human sessions. Specific aspects of paired tutoring seem critical for acquiring referential vocal labels.

Chapter 13 – Grey parrots: Learning and using speech

This chapter briefly describes some of the findings on the cognitive and communicative abilities of grey parrots. Parrots and humans, like songbirds, share aspects of sound production. Grey parrots engage in considerable sound play, including phonetic “babbling” and recombination, and use such abilities to construct new speech patterns from existing ones; they appear to represent their labels acoustically as humans do, and develop phonetic categories. Many studies of the acquisition of referential vocal communication by parrots may ultimately provoke more questions than answers. How do creatures so phylogenetically distant from humans, as parrots learn to pick up on human behavior and learn to speak meaningfully, both in training and in less structured social situations? Are such skills a part of a rich convergent evolution in a wide variety of social creatures, adaptable to the particular social circumstances in which they find themselves? Could it be that other social creatures than ourselves are capable of more than we expect? Only an open mind on the part of researchers and intensive investigative study will answer these questions. Parrots present us with a unique opportunity to re-examine some of our beliefs, prejudices, and expectations about avian abilities.