Core Knowledge of Objects

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Core Knowledge of Objects

Origins of Mind : 06

s.butterfill & [email protected]

When and how do humans first come to know simple facts about particular physical objects?

The question for this course is ... Our current question is about physical objects. How do humans first come to know simple facts about particular physical objects?

In attempting to answer this question, we are focussing on the abilities of infants in the first six months of life.

We are still on the when? question

What have we found so far? ...

What have we found so far?

Here’s what we’ve found so far.

We examined how three requirements on having knowledge of physical objects are met. Knowledge of objects depends on abilities to (i) segment objects, (ii) represent them as persisting and (iii) track their interactions. To know simple facts about particular physical objects you need, minimally, to meet these three requirements.

Three requirements

segment objects
represent objects as persisting (‘permanence’)
track objects’ interactions

The second discovery concerned how infants meet these three requirements this.

Principles of Object Perception

cohesion—‘two surface points lie on the same object only if the points are linked by a path of connected surface points’
boundedness—‘two surface points lie on distinct objects only if no path of connected surface points links them’
rigidity—‘objects are interpreted as moving rigidly if such an interpretation exists’
no action at a distance—‘separated objects are interpreted as moving independently of one another if such an interpretation exists’

Spelke, 1990

The second was that a single set of principles is formally adequate to explain how someone could meet these requirements, and to describe infants' abilities with segmentation, representing objects as persisting and tracking objects' interactions.

This is exciting in several ways. #. That infants have all of these abilities. #. That their abilities are relatively sophisticated: it doesn’t seem that we can characterise them as involving simple heuristics or relying merely on featural information. #. That a single set of principles underlies all three capacities.

three requirements, one set of principles

three requirements, one set of principles: this suggests us that infants’ capacities are characterised by a model of the physical.

1. How do four-month-old infants model physical objects?

2. What is the relation between the model and the infants?

3. What is the relation between the model and the things modelled (physical objects)?

[slide: model] three requirements, one set of principles: this suggests us that infants’ capacities are characterised by a model of the physical (as opposed to being a collection of unrelated capacities that only appear, but don’t really, have anything to do with physical objects).

1. How do four-month-old infants model physical objects?

In asking how infants model physical objects, we are seeking to understand not how physical objects in fact are but how they appear from the point of view of an individual or system.

The model need not be thought of as something used by the system: it is a tool the theorist uses in describing what the system is for and broadly how it works. This therefore leads us to a second question ...

2. What is the relation between the model and the infants?

3. What is the relation between the model and the things modelled (physical objects)?

What have we found so far? ... Apparently conflicting evidence.

Baillargeon et al 1987, figure 1

Shinskey and Munakata 2001, figure 1

More than two decades of research strongly supports the view that infants fail to search for objects hidden behind barriers or screens until around eight months of age (Meltzoff & Moore, 1998, p. \ 202) or maybe even later (Moore & Meltzoff, 2008). Researchers have carefully controlled for the possibility that infants’ failures to search are due to extraneous demands on memory or the control of action. We must therefore conclude, I think, that four- and five-month-old infants do not have beliefs about the locations of briefly occluded objects. It is the absence of belief that explains their failures to search.

	occlusion	endarkening
violation-of-expectations	✔	✘
manual search	✘	✔

Charles & Rivera (2009)

Recall the puzzle .... the discrepancy in looking vs search measures.

Spelke et al 1992, figure 2

Hood et al 2003, figure 1

1. How do four-month-old infants model physical objects?

2. What is the relation between the model and the infants?

3. What is the relation between the model and the things modelled (physical objects)?

Two Candidate Answers to Q2

the Simple View ... generates incorrect predictions

the Core Knowledge View

Let’s check it out

Q1 What is the nature of infants’ earliest cognition of physical objects?

The leading answer is that involves a ‘third type’ of representation, something distinct from perception and knowledge

‘there is a third type of conceptual structure,
dubbed “core knowledge” ...
that differs systematically from both
sensory/perceptual representation[s] ... and ... knowledge.’

Carey, 2009 p. 10

Consider a crude, but hopefully very familiar picture of the adult mind.

The mind has different bits, and these are to an interesting extent independent of each other.

And there are at least three kinds of state, epistemic, motoric and perceptual.

Crude Picture of the Mind

epistemic
(knowledge states)
broadly motoric
(motor representations of outcomes and affordances)
broadly perceptual
(visual, tactual, ... representations; object indexes ...)

These three kinds of state are not inferentially integrated. They can also come apart in the sense that there can be multiple representations in you simultaneously which can’t all be correct. For example, there can be discrepancies between your knowledge of a physical object’s location and where your perceptual systems represent it as being.

Given this crude picture, we might guess that a similar distinction applies to infants’ minds. Then we can ask, Which kind of representation does their abilities to track briefly occluded objects involve?

We know it isn’t knowledge because this view generates incorrect predictions.

We also know it isn’t motoric, because motor representations depend on possibilities for action and when an object is occluded by a barrier which prevents action, it becomes impossible to act on the object.

And, on the face of it, the representation cannot be perceptual. After all, in most of the experiments there is only visual information an occluded object is not providing visual information about its location.

(Interestingly, infants’ problem with searching for occluded objects is not simply caused by an absence of perceptual information concerning the object. (Moore and Meltzoff has a toy make a noise continuously: they found that eight-month-olds failed to search for a toy irrespective of whether it made a noise (Moore & Meltzoff, 2008, p. Experiment 2).)

So we seem to have a problem ... this was the attraction of invoking something exotic like core knowledge

Q1 What is the nature of infants’ earliest cognition of physical objects?

‘there is a third type of conceptual structure,
dubbed “core knowledge” ...
that differs systematically from both
sensory/perceptual representation[s] ... and ... knowledge.’

Carey, 2009 p. 10

core knowledge / core system

For someone to have _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.

‘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.’

Carey and Spelke, 1996 p. 517

‘core systems are

largely innate
encapsulated
unchanging
arising from phylogenetically old systems
built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

representational format: iconic (Carey 2009)

What do people say core knowledge is?

### 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.’ (Carey & Spelke, 1996, p. \ 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: #. largely innate #. encapsulated #. unchanging #. arising from phylogenetically old systems #. built upon the output of innate perceptual analyzers’ (Carey & Spelke, 1996, p. \ 520)

_Note_ There are other, slightly different statements (Carey, 2009, p. e.g.][).

‘We hypothesize that uniquely human cognitive achievements build on systems that humans share with other animals: core systems that evolved before the emergence of our species. The internal functioning of these systems depends on principles and processes that are distinctly non-intuitive. Nevertheless, human intuitions about space, number, morality and other abstract concepts emerge from the use of symbols, especially language, to combine productively the representations that core systems deliver’ (Spelke & Lee, 2012, p. \ 2784-5).

This, them is the two part definition. An analogy and a list of features.

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 Core Knowledge View

The _Core Knowledge View_: the principles of object perception are not knowledge, but they are core knowledge. And we generate expectations from these principles by a process of inference.

Why postulate core knowledge?

The Simple View

The Core Knowledge View

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.

[*looking ahead (don’t say):] Consider this hypothesis. The principles of object perception, and maybe also the expectations they give rise to, are not knowledge. But they are core knowledge. The _core knowledge view_: the principles of object perception are not knowledge, but they are core knowledge. But look at those features 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. So the _first problem_ is that (at this stage) it's unclear what we gain by shifting from knowledge to core knowledge.

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)
number	--""--	--""--
syntax	anticipatory looking	[as adults]
minds	reflected in anticipatory looking, communication, &c	not reflected in judgements about action, desire, ...

The Core Knowledge view may also help us to resolve Discrepant Findings in other domains too ...

Why postulate core knowledge?

The Simple View

The Core Knowledge View

‘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.’

Carey and Spelke, 1996 p. 517

‘core systems are

largely innate
encapsulated
unchanging
arising from phylogenetically old systems
built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

representational format: iconic (Carey 2009)

Recall that we defined core systems by listing properties. [(Actually it was a two-part definition so there’s hope.)]

multiple definitions

One objection is that there are multiple definitions, each slightly different from the others, and no obvious way to choose between them.

But although this indicates that we need to impose some theoretical discipline, it doesn’t seem like an objection that could show there is a deep problem with the notion of Core Knowledge.

Here is a second objection ...

One reason for doubting that the notion of a core system is explanatory 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.)

‘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’

(Adolphs, 2010, p. \ 759)

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’

(Keren & Schul, 2009, p. \ 537)

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’

(Adolphs, 2010, p. \ 759)

Adolphs (2010 p. 759)

Is definition by listing features (a) justified, and is it (b) compatible with the claim that core knowledge is explanatory?

So far I've been explaining objection (a). Now let me say a bit more about (b) ...

We can get the strongest objection by asking ...

Why do we need a notion like core knowledge?

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)
number	--""--	--""--
syntax	anticipatory looking	[as adults]
minds	reflected in anticipatory looking, communication, &c	not reflected in judgements about action, desire, ...

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.

Key question: What features do we have to assign to core knowledge if it's to describe these discrepancies?

In the case of Physical Objects, we want to expalin this puzzling pattern of findings ...

	occlusion	endarkening
violation-of-expectations	✔	✘
manual search	✘	✔

Charles & Rivera (2009)

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.’

Carey and Spelke, 1996 p. 517

‘core systems are

largely innate
encapsulated
unchanging
arising from phylogenetically old systems
built upon the output of innate perceptual analyzers’

(Carey and Spelke 1996: 520)

representational format: iconic (Carey 2009)

Which of these features explain the discrepancy between measures on which infants do, and measures on which they do not, manifest their abilities to track physical objects?

Why do they fail on some search tasks and but pass some v-of-e tasks when the mode of disappearance is occlusion?

And, equally pressingly, why do they do the converse (pass search, fail v-of-e) when the mode is endarkening?

Encapsulated : there are limits on what information can get into the system. But if we are to explain any successes, it must be possible for information about the locations of physical objects to get into the system. So there’s no way we can use encapsulation to explain the puzzling developmental findings.

So, to return to my question,

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

not being knowledge

The answer seems to be: none of the features that are stipluated in introducing it. This gives us a **first objection**: there seems to be a mismatch between the definition and application.

[The feature we most need is actually missing from their list: limited accessibility. But this thought comes later.]

summary

objections to the Core Knowledge View:

multiple definitions
justification for definition by list-of-features
definition by list-of-features rules out explanation
mismatch of definition to application

The Core Knowledge View
generates
no
relevant predictions.

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Core Knowledge of Objects

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