the skulls and brains of others. If active externalism motivates the recognition of a
cognitive prosthesis such as a filofax as ‘part’ of what realises a mind, then the embodied
brain of another can also play that role. Here, then, is our suggestion: that at times
interacting caregiver-infant dyads are neither one individual nor two, but somewhere in
between. At the risk of sounding sensational and un-PC at the same time, infant brains
can be temporarily colonised by caregivers so as to accelerate learning processes.
If this colonisation does happen, it is made possible by a mixture of affective coupling
through interaction, and other mechanisms, such as gaze-following, for co-ordinating
attention (see, e.g. Baron-Cohen 1995 for an attempt to specify the various mechanisms
involved). There is ample evidence, some canvassed above, that the affective state of
either mother or infant has an immediate impact, especially direct in early life, on the
affective state of the other, and that affective state itself generally makes a difference to
the ways in which features of the world are observed and remembered (Zajonc 1980,
1984, Bargh 1990, 1992),15 as well as shaping communicative behaviour (e.g. Dimberg et
al, 2000, Tartter 1980).16 It is not possible directly to ‘install’ some piece of know-how
in an infant, but it is possible, some of the time, to direct its attention, modulate its
attention and arousal, and regulate various types of reward, to make sure that it is
looking in the right direction, at the right time, and in the right way, to pick up on a
pattern which is there to be learned. Some of the available patterns are culturally specific
indexical relationships which caregivers take as symptomatic of how ‘good’ a particular
child is, and which, by structuring caregiver behaviour, open up to the infant a new world
of interaction opportunities.
The instances of indexical learning we describe also permit the beginning of a kind of
‘semiotic arms race’ between infants and caregivers. Once an infant has learned, for
example, that the arms-up gesture can lead to being lifted, it is possible for ‘requests’
(that is, behaviours taken as requests by others, no matter how they are to the infant) to
be lifted to be acted on, or to be refused. Prior to the construction and learning of the
indexical relationship, this was impossible - a parent would lift a child when the parent
wanted to, or thought it would serve some end. Once it has been learned, ‘requests’ can
be differentially responded to, depending on their situation in patterns of interaction
extending through time. Personal and cultural contingencies about infants and parents
will co-determine what patterns are formed, and whether, for example, requested lifting
is more likely after relatively quick acquiescence to silencing behaviour, or less likely in
the period following failure to attend to objects or events in which a caregiver attempted
to arouse interest.
A major shift in the character of this arms race comes with the onset of more deliberate
and fine vocal control on the part of the infant, which brings us to our next example.
[na]∕[b0]
Around the tenth month of life a further striking change in infant interaction is
noticeable. Where before monadic behaviour gave way to dyadic interaction, the infant
now engages the world in a triadic fashion, combining interest in things with joint
behaviour with persons. A striking example is given by the linguist Halliday (1975), who
describes how at 10_ months his son Nigel came to use his father by means of vocal
behaviour.
Nigel produced two distinctive vocal utterances, which Halliday records as [b0] and [na],
and interpreted as, respectively, a request for a favourite toy bird, and a general ‘give me
that’ demand. To respond to [na], in other words, Halliday had to use what was present in
the environment to infer what the child was demanding. Indeed, at Nigel’ s age, children
are likely to be showing early instances of relatively fine and ‘deliberate’ vocal control.
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