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                                           studies. For instance, children and       word gavagai to refer, not to rabbits,
Primer                                     adults were exposed to a new word         but to time-slices of rabbits — to
                                           in the context of a measuring game        entities that only exist for the
                                           with six novel objects. The word was      instant that the word is used? Or
Word Learning                              introduced in passing — ‘Let’s use        that the native isn’t talking about, as
                                           the koba to measure which is              Quine puts it, ‘all and sundry
Paul Bloom                                 longer… We can put the koba away          undetached parts of rabbits’?
                                           now’. Children weren’t asked to           Indeed, how could the linguist
Word learning is a controversial area,     repeat the new word and weren’t           know that gavagai is a name at all, as
but there are two facts that               tested to ensure that they heard it.      opposed to the native clearing his
everyone agrees about. The first is        They were tested a full month later,      throat, or making a noise to warn the
that words really do have to be            by bringing out the same objects and      animal away, or saying the
learned. Regardless of how much of         asking them to ‘Show me the koba’.        equivalent of ‘Look!’ or ‘I’m
conceptual structure and linguistic        Even 3-year-olds choose the correct       bored!’.
knowledge is innate, the specific          object over half of the time, far             Quine used this example to
links between sounds (or signs) and        better than chance. Furthermore,          defend a skeptical position about
meanings must be determined on             there were no age differences —           language — that there really is no
the basis of experience. No matter         3-year-olds did just as well as adults.   such thing as the meaning of a word.
how intelligent a British baby is, for     Further studies have found similar        But contemporary scholars in word
instance, she has to learn that dogs       abilities even in 2-year-olds.            learning have used it to support a
are called ‘dogs’, that sleeping is                                                  different moral: Since children do
called ‘sleeping’, and so on.              The problem of word learning              solve these problems of reference
    The second agreed-upon fact is             What precisely is so impressive       and generalization, this suggests
that children are strikingly good at       about this ability? There is good         that they are somehow constrained
this sort of learning. Children utter      reason to believe that it is              or biased to favor some
their first words by 12 months of          impressive since, as far as we know,      interpretations over others. For
age, are relatively proficient at word     no species others than humans can         instance, in the gavagai situation,
learning by 16–18 months, and              learn words and certainly no              children, as well as adults, will tend
eventually come to learn new words         computer has ever been construed          to take the word as naming the
at a rate of well over ten new words       that can do so. The problem of word       entire object. They are not limited
per day.                                   learning is surprisingly deep, and        to an object interpretation, however.
    Children’s first words include         the reason for this was most              In other situations they can
personal pronouns (me), proper             famously demonstrated by the              entertain non-object interpretations
names (Mommy), prepositions (on),          philosopher W.V.O. Quine, who             of a new word, which is a capacity
adjectives (big), verbs (want), and        gave the example of a linguist            necessary in order to learn
many classes of nouns, including           witnessing a rabbit scurry by, and        adjectives (such as ‘white’), verbs
those referring to whole objects           hearing a native say ‘Gavagai’. It        (such as ‘jumping’), and so on.
(dog), substances (water), parts           turns out that there is an infinity of
(finger), habitual activities (nap), and   logically possible meanings for this      How is the problem solved?
abstract notions (story). While            new word gavagai. It could refer to           There are several cognitive
children sometimes get confused            rabbits, but it could also refer to the   systems that work together to make
about the precise meaning of word,         specific rabbit named by the native,      word learning possible. Some of
serious mistakes almost never occur.       or to any mammal, or any animal, or       these involve memory–word
This successful word learning              any object. It could refer to the top     learning and require the capacity to
occurs even in conditions in which         half of the rabbit, or its outer          encode, store, and access arbitrary
children are not taught words in any       surface, or to rabbits but only those     mappings; in this case, between
non-trivial sense, such as when            that are scurrying; it could refer to     sounds (or signs) and meanings.
children are abused and neglected.         scurrying itself, or to white, or to      There are also conceptual
                                           furriness. The linguist could             capacities. In order to learn words
Minimal cues                               exclude some of these                     for kinds of objects, properties, and
   Given how many words children           interpretations through further           actions, say, the child has to have
come to know (about 10,000 words           questioning and further experience        some non-linguistic understanding
by age 6), one would expect them to        with the word, but some                   of what such words mean. One
be able to learn words in very             interpretations are harder to             reason why children will never
minimal circumstances. This                exclude. How could the linguist           assume that gavagai means time-
expectation is born out by several         know that the native isn’t using the      slices of rabbit is because these are
R6   Current Biology Vol 11 No 1

not natural hypotheses for a word         ‘toma’ referred to. In another study,   understanding of the beliefs and
learner to entertain — while              an adult used a novel verb to declare   intentions of other people, and a
categories like rabbit and animal are.    her intention to perform an action      sensitivity to syntax. An act as
    A further system involves             (e.g. ‘I am going to blork!’),          seemingly simple as a 2-year-old
children’s appreciation of the mental     proceeded to do an action               learning the word rabbit draws upon
states of other people, what is           ‘accidentally’ (saying ‘Whoops!)        many of the capacities that are
sometimes called ‘naïve psychology’       and then performed another action,      central to the human mind.
or ‘theory of mind’. There is             with satisfaction (saying ‘There!’
abundant evidence that children           with a pleased expression).             Suggestions for further reading
will take a word as referring to a        Children connected the verb with        1.    Baldwin DA, Moses LM: Early
                                                                                        understanding of referential intent and
given object if and only if there is      the action the speaker seemed                 attentional focus: Evidence from
evidence that the speaker intended        satisfied with, not the accidental            language and emotion. In Children’s Early
to refer to that object. If an 18-        one. Such studies indicate that               Understanding Of Mind: Origins and
                                                                                        Development. Edited by Lewis C, Mitchell
month-old hears a novel label as she      young children infer the intention of         P. Hillsdale, NJ: Erlbaum. 1994: 133-156.
is playing with a novel toy, she will     the speaker (through attention to       2.    Bloom P: How Children Learn the
only assume that the word is a name       cues that include line-of-regard and          Meanings of Words. Cambridge, MA: MIT
                                                                                        Press; 2000.
for the toy if the label is spoken by     emotional indications of                3.    Gleitman LR: The structural sources of
someone who is also attending to          satisfaction) when determining the            word meaning. Lang Acquisition 1990,
the toy. If she just hears a              referent of a new word, for both              1:3-55.
                                                                                  4.    Markman EM: Constraints children place
disembodied voice naming the              nouns and verbs.                              on word meanings. Cognitive Sci 1990,
object as she is looking at it (e.g. ‘A       Finally, even young children              14:57-77.
dawnoo! There’s a dawnoo!’), the          attend to the syntax of a word when     5.    Markson L, Bloom P: Evidence against a
                                                                                        dedicated system for word learning in
word is not mapped onto that              determining what the word means.              children. Nature 1997, 385:813-815.
object.)                                  The classic study showing this was
    Another study tested babies in a      done by Roger Brown, who showed         Address: Department of Psychology, Yale
context in which they were given          preschoolers a picture of a strange     University, New Haven, Connecticut 06520-
one object to play with while             action being performed on a novel       8205, USA.
another object was put into a bucket      substance using an unfamiliar
that was in front of the                  object. One group of children was
experimenter. When the baby was           told ‘Do you know what a sib is? In          The editors of Current Biology welcome
looking at the object in front of her,    this picture, you can see a sib’             correspondence on any article in the
the experimenter looked at the            (count noun syntax), a second group          journal, but reserve the right to reduce
object in the bucket and said a new       was told ‘Have you seen any sib? In          the length of any letter to be published.
                                                                                       All Correspondence containing data or
word, such as ‘It’s a modi!’. 18-         this picture, you can see sib’ (mass
                                                                                       scientific argument will be refereed.
month-olds looked at the                  noun syntax), and a third group was          Items for publication should either be
experimenter and redirected their         told ‘Have you seen sibbing? In this         submitted typed, double-spaced to: The
attention to what she was looking at,     picture, you can see sibbing’ (verb          Editor, Current Biology, Elsevier
in this case, at the object in the        syntax). The preschoolers tended to          Science London, 84 Theobald’s Road,
bucket. And when later shown the          construe the count noun as referring         London, WC1X 8RR, UK, or sent by
                                                                                       electronic mail to
two objects and asked to ‘find the        to the object, the mass noun as    
modi’, children assume that the           referring to the substance, and the
word refers to the object the             verb as referring to the action.
experimenter was looking at when          Subsequent research has found that
she said the word — not the object        syntactic cues can help children to
that the child herself was looking at.    learn words belonging to a range of
    More sophisticated intentional        different ontological categories, and
capacities are displayed by 24-           might play an especially important
months olds. In one study, an adult       role in how they learn the meanings
announced her intention to find an        of abstract verbs such as ‘thinking’
object — ‘Let’s find the                  and ‘receiving’.
toma!’ — and then picked up and               Research to date suggests that
nonverbally rejected (by frowning)        children learn words through a set
two other objects before picking up       of diverse capacities, including
a third object and smiling. Despite       memory, an appreciation of the
the temporal gap, children inferred       categories and individuals that make
that this third object was what           up the external world, an

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