The Alex Studies: Cognitive and Communicative Abilities of Grey Parrots
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Can a parrot understand complex concepts and mean what it says? Since the early 1900s, most studies on animal-human communication have focused on great apes and a few cetacean species. Birds were rarely used in similar studies on the grounds that they were merely talented mimics--that they were, after all, "birdbrains." Experiments performed primarily on pigeons in Skinner boxes demonstrated capacities inferior to those of mammals; these results were thought to reflect the capacities of all birds, despite evidence suggesting that species such as jays, crows, and parrots might be capable of more impressive cognitive feats.
Twenty years ago Irene Pepperberg set out to discover whether the results of the pigeon studies necessarily meant that other birds--particularly the large-brained, highly social parrots--were incapable of mastering complex cognitive concepts and the rudiments of referential speech. Her investigation and the bird at its center--a male Grey parrot named Alex--have since become almost as well known as their primate equivalents and no less a subject of fierce debate in the field of animal cognition. This book represents the long-awaited synthesis of the studies constituting one of the landmark experiments in modern comparative psychology.
questioner and the other always the respondent, and how the process can be used to effect environment change. An excerpt from a training session on the label ‘‘ﬁve’’ is presented in Table 2.1, and the physical arrangement for a different session is depicted in I: (Acting as trainer): Bruce, what’s this? B: (Acting as model/rival): Five wood. I: That’s right, ﬁve wood. Here you are . . . ﬁve wood. (Hands over ﬁve wooden craft sticks. B begins to break one apart, much as Alex would.) A: ‘ii wood.
intra- as well as interobserver reliability by seeing if we interpreted the same vocalization the same way on subsequent hearings. We did not, however, use spectrographic analysis to identify or compare utterances. Unlike bird song, which is fairly stereotypic from one rendition to the next (see, e.g., Greenewalt 1968) and for which spectrographic analysis is widely used, speech production, whether by people or parrots, often differs considerably from one rendition to the next, and the same
feature the experimenter chooses (see, e.g., Nelson 1988). Starlings, mockingbirds (Mimus polyglottos), and cowbirds, for example, can classify novel series of tones as ascending or descending—that is, as ‘‘same’’ or ‘‘different’’ from ascending or descending reference series—but only for sequences that are within the range of frequencies used in training (Hulse and Cynx 1985). None of these studies, however, showed actual labeling of the relation of sameness or difference or, for example,
differed little. Based on a test for differences in proportions (.05 conﬁdence level), his scores were not signiﬁcantly better for questions involving novel items versus familiar ones for all trials, and were only just signiﬁcantly better when examined for ﬁrst trial performance only. At ﬁrst, I was perplexed by Alex’s accuracy, because subjects usually perform less well on transfer tests; I was concerned that he was being cued in some manner. Close analysis of our testing situation revealed no
1994a). Might Alex show such capacities? If, as some researchers suggest, capacities necessary for numerical competence are used for other complex cognitive tasks (Gallistel 1993), the answer should be afﬁrmative. To What Extent Can a Parrot Understand and Use Numerical Concepts? / 114 ropean blackbirds, Turdus merula, Wolfgramm and Todt 1982; wood pewees, Contopus virens, Smith 1988; eastern kingbirds, Tyrannus tyrannus, Smith and Smith 1992). In the laboratory, great tits, after learning to