In an article in Science Kaminski reported that a 9-year old Border Collie knew the names of more than 200 items. Their first experiment demonstrated that Rico’s acquisition of the names of toys was indeed genuine not a “Clever Hans” phenomenon, in which the successful retrieval of toys would be due to subtle cues other than the words. Their second experiment demonstrated Rico’s “exclusion learning” inferring the name of an object based on its novelty in the midst of familiar objects (Carey and Bartlett, 1978).
As an example, Carey and Bartlett arranged a scenario during which 3 and 4-year-old children were shown two trays and asked to retrieve the “chromium, not the red tray.” Despite the children’s lack of knowledge of the word chromium as a shade of green, the children correctly inferred that the teacher wanted the green tray. Carey and Bartlett dubbed this rapid linking of a proper-noun label upon an object as “fast mapping.” Markman and Abelev (2004) found the report of Rico’s apparent exclusion learning to be fascinating. Demonstrations of word learning by exclusion in children have usually led researchers to conclude that the child has learned Baldwin’s (1993) elements of referential understanding.
Baldwin’s work with children led her to conclude that if learning is limited to “associative factors” alone, learning would be slow. She identified two elementary factors of referential understanding that she believed to be necessary to expedite rapid word learning by children:
(a) awareness that words may refer to objects, and
(b) awareness of social cues that enable the mapping of the words upon the referent. Testing her hypotheses, Baldwin tried to eliminate associative factors by pitting temporal contiguity against her two elements of referential understanding. Anexperimenter presented two opaque containers to infants. Looking inside the first container, the experimenter exclaimed, “It’s a modi.” Immediately thereafter, the experimenter withdrew the toy from the second container and gave it to the child for play.
After a 10-s delay, the object in the first container was also given to the infant for play. Baldwin assumed that if associations based on temporal contiguity alone were critical for learning, the infants would identify the object from the second container as “modi.” However, despite the 10-s delay, the infants chose the object in the first container as “modi” indicating that awareness of the reference cue influenced choice more than simple temporal contiguity. Baldwin concluded that fast word learning is mediated by referential understanding as opposed to associative mechanisms. Thus, the conclusion by Kaminski et al. (2004) that a Border Collie is able to learn words rapidly by exclusion invites intriguing questions about the differences in word learning between dogs and children.
Border Collie Procedure Training
We taught Chaser one or two proper-noun names per day. Several trainers taught Chaser using the same procedures. All trainers were consistent in their use of the correct proper nouns because the name of each object waswritten on the object. Most of the training took place in our home and front and back yards. Each timewe gave Chaser a new name to learn, we held and pointed to the object to be associated with the name and always said, “Chaser, this is . Pop hide. Chaser find .” No other objects were available on the floor for retrieval, so errors were unlikely. A 3–5 min play rehearsal period followed retrieval.
During trials and play rehearsal periods, we repetitively verbalized the name of the object 20–40 times each session in order to facilitate the association of the name and object. Following the initial training in the absence of other objects, the newly learned object was placed on the floor among other objects that had been recently learned our working group. Over a period of 2–4 weeks, we gave Chaser daily rehearsal testing and play with these items, during which we repeatedly paired the name with the object, along with reinforcing play. As Chaser’s vocabulary for proper-nouns grew, ultimately 50 or more newly learned objects were usually available in open Tupperware tubs for play and rehearsal testing, which could be initiated by Chaser or a trainer.
As new names were learned, they were phased in for daily rehearsal and the older objects were phased out of the working group until monthly tests were given. When Chaser failed to retrieve an object upon command, we removed the other objects and gave Chaser additional training trials until she met our learning criterion (described below). Subsequently, the working group of objects was returned, and play with rehearsal testing continued. No object was removed from the working group unless Chaser fulfilled our learning criteria. The procedure of teaching the names of humans, dogs, cats, locations, and stationary objects was similar to that used in teaching the names of objects, except that we told Chaser to “go to” the designated target both during learning and during testing. Rewards were praise and the opportunity to engage in enjoyable activities, such as “playing catch” with one of her toys.
We adjusted our daily training procedures, the duration of our sessions, and the amount of rehearsal to adapt to Chaser’s ability to learn and retain new words. Each time Chaser made an error with any name object pair, we provided additional training with that word until Chaser again completed the learning criterion for that name object pair. Therefore, the majority of most training sessions involved rehearsal of previously learned words and many tests of retained knowledge. This procedure allowed us to measure Chaser’s cumulative knowledge of proper nouns and to ensure that Chaser’s vocabulary was increasing systematically, rather than new knowledge replacing previous knowledge.
Because we adjusted our daily procedures to meet Chaser’s retention and to keep her interested in the tasks, our training procedures did not allow us to assess the maximum rate of word learning or the maximum number of words that Chaser could learn. We were not concerned with measuring Chaser’s innate abilities independent of training; rather, our primary goal was to discover what language accomplishments Chaser might achieve when given daily intensive training over years.
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