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Core Knowledge

I talked about the notion of core knowledge in the very first lecture, but since then I have not appealed to the notion. This is deliberate because the notion is tricky; so I thought it would be good to postpone our discussion of it for as long as possible. Now I can put it off no longer.

What is core knowledge? What are core systems?

The first, very minor thing is to realise that there are two closely related notions, core knowledge and core system. These are related this: roughly, core knowledge states are the states of core systems. More carefully:
For someone to have \textit{core knowledge of a particular principle or fact} is for her to have a core system where either the core system includes a representation of that principle or else the principle plays a special role in describing the core system.
So we can define core knowlegde in terms of core system.
What do people say core knowledge is?
\subsection{Two-part definition}
There are two parts to a good definition. The first is an analogy that helps us get a fix on what we is meant by 'system' generally. (The second part tells us which systems are core systems by listing their characteristic features.)

‘Just as humans are endowed with multiple, specialized perceptual systems, so we are endowed with multiple systems for representing and reasoning about entities of different kinds.’

\citep[p.\ 517]{Carey:1996hl}

(Carey and Spelke 1996: 517)

So talk of core knowledge is somehow supposed to latch onto the idea of a system.
What do these authors mean by talking about 'specialized perceptual systems'?
They talk about things like perceiving colour, depth or melodies.
Now, as we saw when talking about categorical perception of colour, we can think of the 'system' underlying categorical perception as largely separate from other cognitive systems--- we saw that they could be knocked out by verbal interference, for example.
So the idea is that core knowledge somehow involves a system that is separable from other cognitive mechanisms.
As Carey rather grandly puts it, understanding core knowledge will involve understanding something about 'the architecture of the mind'.
Illustration: edge detection.

‘core systems are

  1. largely innate
  2. encapsulated
  3. unchanging
  4. arising from phylogenetically old systems
  5. built upon the output of innate perceptual analyzers’

\citep[p.\ 520]{Carey:1996hl}.

(Carey and Spelke 1996: 520)

\textit{Note} There are other, slightly different statements \citep[e.g.][]{carey:2009_origin}.
This, them is the two part definition. An analogy and a list of features.

representational format: iconic (Carey 2009)

There is one more feature that I want to mention; this is important although I won't disucss it here.
To say that a represenation is iconic means, roughly, that parts of the representation represent parts of the thing represented.
Pictures are paradigm examples of representations with iconic formats.
For example, you might have a picture of a flower where some parts of the picture represent the petals and others the stem.
The first problem we encountered was that the Simple View is false. But maybe we can appeal to the Core Knowledge View.
According to the Core Knowledge View, the principles of object perception, and maybe also the expectations they give rise to, are not knowledge. But they are core knowledge.
This raises some issues. Is the Core Knowledge View consistent with the claims that we have ended up with, e.g. about categorical perception and the Principles of Object Perception characterising the way that object indexes work? I think the answer is, basically, yes. Categorical perception involves a system that has many of the features associated with core knowledge.
But before going further, I think we critically examine the notion and see whether we really understand what core knowledge is.

The Simple View

The Core Knowledge View

As a sort of aside, I might mention for anyone familiar with Fodor on modularity that core systems basically coincide modules.

core system vs module

Aside: compare the notion of a core system with the notion of a module
The two definitions are different, but the differences are subtle enough that we don't want both.
My recommendation: if you want a better definition of core system, adopt core system = module as a working assumption and then look to research on modularity because there's more of it.
An example contrasting Grice and Davidson on the wave.
\subsection{Compare modularity}
Modules are ‘the psychological systems whose operations present the world to thought’; they ‘constitute a natural kind’; and there is ‘a cluster of properties that they have in common’ \citep[p.\ 101]{Fodor:1983dg}.
These properties include:
\begin{itemize}
\item domain specificity (modules deal with ‘eccentric’ bodies of knowledge)
\item limited accessibility (representations in modules are not usually inferentially integrated with knowledge)
\item information encapsulation (modules are unaffected by general knowledge or representations in other modules)
\item innateness (roughly, the information and operations of a module not straightforwardly consequences of learning; but see \citet{Samuels:2004ho}).
\end{itemize}

‘core systems are

  1. largely innate,
  2. encapsulated, and
  3. unchanging,
  4. arising from phylogenetically old systems
  5. built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

Modules are ‘the psychological systems whose operations present the world to thought’; they ‘constitute a natural kind’; and there is ‘a cluster of properties that they have in common’

  1. innateness
  2. information encapsulation
  3. domain specificity
  4. limited accessibility
  5. ...

But is the notion of core system (or module) explanatory?

One reason for doubting that the notion of a core system is explanator arises from the way we have introduced it. We have introduced it by providing a list of features. But why suppose that this particular list of features constitutes a natural kind? This worry has been brought into sharp focus by criticisms of 'two systems' approaches. (These criticisms are not directed specifically at claims about core knowledge, but the criticisms apply.)
\subsection{Objection}

‘there is a paucity of … data to suggest that they are the only or the best way of carving up the processing,

‘and it seems doubtful that the often long lists of correlated attributes should come as a package’

\citep[p.\ 759]{adolphs_conceptual_2010}

Adolphs (2010 p. 759)

‘we wonder whether the dichotomous characteristics used to define the two-system models are … perfectly correlated …

[and] whether a hybrid system that combines characteristics from both systems could not be … viable’

\citep[p.\ 537]{keren_two_2009}

Keren and Schul (2009, p. 537)

This is weak.
Remember that criticism is easy, especially if you don't have to prove someone is wrong.
Construction is hard, and worth more.
Even so, there is a problem here.

‘the process architecture of social cognition is still very much in need of a detailed theory’

\citep[p.\ 759]{adolphs_conceptual_2010}

Adolphs (2010 p. 759)

Given the problems, maybe we should just abandon the notions of core system and core knowledge. After all, we have come this far without them.

Why do we need a notion like core system?

So why do we need a notion like core knowledge?
Think about these domains.
In each case, we're pushed towards postulating that infants know things, but also pushed against this.
Resolving the apparent contradiction is what core knowledge is for.
domain evidence for knowledge in infancy evidence against knowledge
colour categories used in learning labels & functions failure to use colour as a dimension in ‘same as’ judgements
physical objects patterns of dishabituation and anticipatory looking unreflected in planned action (may influence online control)
minds reflected in anticipatory looking, communication, &c not reflected in judgements about action, desire, ...
syntax [to follow] [to follow]
number [to follow] [to follow]
Key question: What features do we have to assign to core knowledge if it's to describe these discrepancies?
I think the fundamental feature is inaccessibility.
If this is what core knowledge is for (if it exists to explain these discrepancies), what features must core knowledge have?

If this is what core knowledge is for, what features must core knowledge have?

‘Just as humans are endowed with multiple, specialized perceptual systems, so we are endowed with multiple systems for representing and reasoning about entities of different kinds.’

\citep[p.\ 517]{Carey:1996hl}

(Carey and Spelke 1996: 517)

‘core systems are

  1. largely innate
  2. encapsulated
  3. unchanging
  4. arising from phylogenetically old systems
  5. built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

representational format: iconic (Carey 2009)

Look at those features characterising core knowledge as defined by Carey and Spelke again -- innate, encapsulated, unchanging and the rest. None of these straightforwardly enable us to predict that core knowledge of objects will guide looking but not reaching. (I'll say in a moment: The iconic format is important, but because it explains a missing feature, namely limited accessibility.)
The feature we most need is actually missing from their list.

If this is what core knowledge is for, what features must core knowledge have?

limited accessibility to knowledge

To say that a system or module exhibits limited accessibility is to say that the representations in the system are not usually inferentially integrated with knowledge.
I think this is the key feature we need to assign to core knowledge in order to explain the apparent discrepancies in the findings about when knowledge emerges in development.
Limited accessbility is a familar feature of many cognitive systems.
When you grasp an object with a precision grip, it turns out that there is a very reliable pattern.
At a certain point in moving towards it your fingers will reach a maximum grip aperture which is normally a certain amount wider than the object to be grasped, and then start to close.
Now there's no physiological reason why grasping should work like this, rather than grip hand closing only once you contact the object.
Maximum grip aperture shows anticipation of the object: the mechanism responsible for guiding your action does so by representing various things including some features of the object.
But we ordinarily have no idea about this.
The discovery of how grasping is controlled depended on high speed photography.
This is an illustration of limited accessibility.
(This can also illustrate information encapsulation and domain specificity.)

maximum grip aperture

(source: Jeannerod 2009, figure 10.1)

To sum up, there are two problems with the notion of core knowledge ...

core systems -- questions:

  1. Is appealing to core systems (modules) explanatory?
  2. Can the Core Knowledge View explain the discrepancy?
  3. Is the view I've been developing consisten with the Core Knowledge View?
  4. Is core knowledge all one thing?
  5. How do you get from core knowledge to knowledge knowledge?
The Core Knowledge View is the view that infants' competence with objects, causes, colours and the rest depends not on knowledge (as the Simple View has it) but on core knowledge.
On the first question, I could tell you a long story about computational processes and representational formats. But I won't do that here.
On the second question, I think the answer is probably yes because the difference in representational formats between knowledge proper and core knowledge explains limited accessibility, and this in turn partially explains the discrepancies. (But note that it doesn't explain is why the discrepacies fall exactly where they do.)
On the third question, I think that thinking about categorical perception, or the perceptual systems that underpin objects indexes is a way of getting at what core knowledge really involves. Core systems are not always something over and above perceptual and motor systems (although it seems probably that they sometimes are if our competence with syntax rests on core knowledge).
On the fourth question, Most people are committed to there being different stories for (a) colour (categorical perception); (b) syntax (tacit knowledge); and (c) physical objects. I'm not sure. I'm tempted to think that perceptual and motor cognition are at the root of these in every case, but this is a radical idea for which there is currenly very little evidence.
The fifth question is just a variant of what I called The Problem (see lecture 2; it arises from the failure of the Simple View).
This picture is significantly different from some competitors (but not Carey on number):
(1) because it shows we aren't done when we've explained the acquisition of core knowledge (contra e.g. Leslie, Baillargeon), and
(2) because it shows we can't hope to explain the acquisition of knowledge if we ignore core knowledge (contra e.g. Tomasello)