Lecture 06 (Colloquium Talk) | Origins of Mind (Umea)

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On the
Developmental Origins of
Knowledge of Physical Objects

Cognitive development---the fact that humans typically begin life with quite limited cognitive abilities and gradually acquire more---raises some fundamentally philosophical challenges.

Despite this, cognitive development has been quite widely ignored by contemporary philosophers of mind. But it wasn’t always like this ...

‘... ’tis past doubt,
that Men have in their Minds several Ideas ...:
It is in the first place to be enquired,
How he comes by them?’\citep[p.\ 104]{Locke:1975qo}

(Locke, 1689 p. 104)

As Locke saw it, questions about the nature of minds are bound up with questions about their developmental origins.

Where Locke asked a question about Ideas, I want to consider a perhaps simpler question about knowledge. How do humans make the transition from not knowing any simple facts about particular things in a given domain to possessing some such knowledge?

Research on this question in developmental psychology motivates a further question. How can we understand partially formed minds and the actions they give rise to? What representations and processes are needed to explain these actions? (Special kind of knowledge, like ‘core knowledge’?)

On the
Developmental Origins of
Knowledge of Physical Objects

In this talk I shall focus on knowledge of physical objects as a case study.

So this is a talk about ONE [NOT two] related questions. First, What is the nature of infants’ earliest cognition of physical objects?

Questions: \begin{enumerate} \item What is the nature of infants’ earliest cognition of physical objects? \item How do you get from these early forms of cognition to knowledge of simple facts about particular physical objects? \end{enumerate}

Let me start by reviewing some quite famous experimental findings about infants’ capacities to track briefly occluded physical objects.

A wide range of evidence suggests that

4- and 5-month-olds can track briefly occluded objects.

Let me illustrate with an old and famous experiment by Karen Wynn involving 5-month-old subjects ...

Wynn 1992, fig 1 (part)

Consider this famous violation-of-expectations experiment by \citet{wynn:1992_addition}. Her subjects were five-month-olds.

How many mice do infants expect there to be ?

Here you see the results. The looking times are always over 10 seconds, and infants look more than a second longer (mean looking time) at the impossible event.

This is good evidence that 5-month-olds can track briefly occluded objects. And indeed much further evidence supports this view ...

The ‘baseline’ refers to a pretest in which infants were simply shown a display containing one object, or else a display containing two objects, and the question was whether they would prefer to look at one object or at two. In fact, they didn’t have a preference.

There is a wide range of evidence that four- and five-month-olds can track briefly occluded objects. Such evidence comes from infants’ reactions to a range of different scenarios. Some scenrios involve a comparision between the number of objects \citep[e.g.][]{spelke:1995_spatiotemporal}, others involve infants’ abilities to track the causal effects of unperceived objects \citep[e.g][]{baillargeon:1987_object}, while others require infants to track properties such as the shape and size of unperceived objects \citep[e.g.][]{wang:2004_young}, or to remember the location of a hidden object \citep[e.g.][]{wilcox:1996_location}.

The evidence also comes from studies using a variety of different methods including habituation \citep[e.g.][]{spelke:1995_spatiotemporal}, violation-of-expectations \citep[e.g.][]{wang:2004_young}, and anticipatory looking \citep[e.g.][]{rosander:2004_infants,bertenthal:2013_differential}.

4- to 6-month-olds can track briefly occluded objects

scenario method source

1 vs 2 objects habituation Spelke et al 1995

one unperceived object constrains another’s movement habituation Baillargeon 1987

where did I hide it? violation-of-expectations Wilcox et al 1996

wide objects can’t disappear behind a narrow occluder violation-of-expectations Wang et al 2004

when and where will it reappear? anticipatory looking Rosander et al 2004

marker of object maintenanc EEG Kaufman et al 2005

scenario	method	source
1 vs 2 objects	habituation	Spelke et al 1995
one unperceived object constrains another’s movement	habituation	Baillargeon 1987
where did I hide it?	violation-of-expectations	Wilcox et al 1996
wide objects can’t disappear behind a narrow occluder	violation-of-expectations	Wang et al 2004
when and where will it reappear?	anticipatory looking	Rosander et al 2004
marker of object maintenanc	EEG	Kaufman et al 2005

I have described these findings as supporting a conclusion about tracking rather than about representing.

For a process to \emph{track} the path of an occluded object is for it to nonaccidentally depend in some way on the occluded object’s path: in an interesting but limited range of situations, changes to the object’s path will cause corresponding changes to how the process unfolds. Relatedly, to say that someone can track occluded objects is to say that there are processes in her (or otherwise appropriately involving her) which track the paths of some occluded objects.

How?

The fact that four- and five-month-olds can track briefly occluded objects raises a question. How do they do this?

core knowledge / belief?

How do infants track briefly occluded objects? An early idea was that infants’ earliest abilities involved knowledge of physical objects. On this view, infants know simple principles governing how objects behave (for example, that they follow continuous paths through space and time) and infants know the locations of some briefly occluded objects. In an early paper Spelke offered a strong statement of this view.

[SAY EARLIER THAT ONE SCREEN IS TRANSPARENT]

To illustrate, consider an ingenious experiment by \citet{Shinskey:2001fk}. There was an opaque screen that could rotate between lying flat on the ground and being raised to conceal a toy behind it. \citeauthor{Shinskey:2001fk} also used a second piece of apparatus just like the first except that the screen was transparent rather than opaque. They reasoned that infants would quite often pull the screen forwards just for fun, regardless of what is behind it. However, they also guessed that when infants know there is an interesting toy behind the screen, then they will pull it forwards more often than when they know that there is nothing behind the screen. This is just what happened when infants were presented with the apparatus involving a transparent screen: they sometimes pulled the screen forwards when there was no toy behind it, but they pulled it forwards significantly more often when the toy was behind it. What happened when infants were presented with the opaque screen? Here infants pulled the screen forwards no more often when they had observed a toy being placed behind it then when they had observed that there was nothing behind it. This is evidence that seven-month-old infants do not know that a toy they have very recently seen hidden behind a screen is behind the screen. After all, since knowledge guides action we would expect infants who know that a toy is behind an opaque screen to pull the screen forward more often than infants who know there is nothing behind the screen, just as they do when the screen is transparent.

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 \citep[p.\ 202]{Meltzoff:1998wp} or maybe even later \citep{moore:2008_factors}. 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.

Here are their results with 7-month old infants.

We are interested in whether infants were more likely to pull the screen forwards when the object was present than when it was absent. Since infants wanted the toy, if they knew it was behind the barrier they should have pulled forward the barrier more often when the toy was behind it. This is exactly what they did when the barrier was transparent. But look what happens when the barrier is opaque, so that the toy is not visible to infants when they have to prepare the pulling action: they no longer pull the barrier more often when the toy was behind it.

This is good evidence that 7 month olds do not know facts about the locations of objects they cannot perceive. And this is not isolated evidence; for example, \citet{moore:2008_factors} use a different methods also involving manual search to provide converging evidence for this conclusion. But now we have a problem ...

Because this point is controversial, I want to mention one further piece of the puzzle.

What happens if we change the way an object disappears. Instead of occluding it?

There’s much evidence that infants will reach for an object hidden in darkness \citep[e.g.][]{jonsson:2003_infants}.

But what happens if instead of measuring reaching we measure looking times? \citet{charles:2009_object} compared what happens when an object is momentarily hidden behind a screen with what happens when an object is momentarily hidden by darkness. They used a trick with light and mirrors so that for some of the infants, the object did not reappear when the screen came up or the light returned. Surprisingly, five-month-old infants’ looking times indicated that an expectation had been violated only when the object was hidden behind a screen but not when hidden by darkness.

So five-month-olds not only sometimes fail to search for hidden objects but also sometimes fail to look longer when a momentarily hidden object fails to reappear as if by magic.

I think this pattern of findings is good evidence against the hypothesis that four- or five-month-olds have beliefs about, or knowledege of, the locations of unperceived objects. After all, a belief is essentially the kind of state that can inform actions of any kind, whether they involve looking, searching with the hands or anything else.

While this view still has adovates (notably Renee Baillargeon), many researchers have rejected this view because it generates too many incorrect predictions.

... on ‘core knowledge’.

occlusion endarkening

violation-of-expectations ✔ ✘

manual search ✘ ✔

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

Charles & Rivera (2009)

‘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

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

largely innate
encapsulated
unchanging
arising from phylogenetically old systems
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.

First problem: 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?

4- to 6-month-olds can track briefly occluded objects

scenario method source

1 vs 2 objects habituation Spelke et al 1995

one unperceived object constrains another’s movement habituation Baillargeon 1987

where did I hide it? violation-of-expectations Wilcox et al 1996

wide objects can’t disappear behind a narrow occluder violation-of-expectations Wang et al 2004

when and where will it reappear? anticipatory looking Rosander et al 2004

marker of object maintenanc EEG Kaufman et al 2005

scenario	method	source
1 vs 2 objects	habituation	Spelke et al 1995
one unperceived object constrains another’s movement	habituation	Baillargeon 1987
where did I hide it?	violation-of-expectations	Wilcox et al 1996
wide objects can’t disappear behind a narrow occluder	violation-of-expectations	Wang et al 2004
when and where will it reappear?	anticipatory looking	Rosander et al 2004
marker of object maintenanc	EEG	Kaufman et al 2005

How?

So theories of core knowledge do not seem to be equipped to explain existing patterns in infants’ successes and failures in tracking briefly occluded objects. Nor do they generate new predictions. Let us therefore put them to one side for the moment.

If it isn’t a matter of knowledge, and if it can’t be explained by appeal to core knowledge, then how do four- and five-month-olds track briefly occluded objects?

Sometimes when you’re looking for a theory, less is more.

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. (\citeauthor{moore:2008_factors} 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 \citep[Experiment 2]{moore:2008_factors}.)

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

But we should reconsider the possibility that infants’ abilities to track briefly occluded objects do indeed depend on perceptual information because there are some broadly perceptual representations that do can specify the locations of occluded objects ...

... namely, object indexes.

object indexes

In adult humans, there is a system of object indexes which enables them to track potentially moving objects in ongoing actions such as visually tracking or reaching for objects, and which influences how their attention is allocated \citep{flombaum:2008_attentional}.

But what is an object index? Formally, an object index is ‘a mental token that functions as a pointer to an object’ \citep[p.\ 11]{Leslie:1998zk}. If you imagine using your fingers to track moving objects, an object index is the mental counterpart of a finger \citep[p.~68]{pylyshyn:1989_role}.

Leslie et al say an object index is ‘a mental token that functions as a pointer to an object’ \citep[p.\ 11]{Leslie:1998zk}

‘Pylyshyn’s FINST model: you have four or five indexes which can be attached to objects; it’s a bit like having your fingers on an object: you might not know anything about the object, but you can say where it is relative to the other objects you’re fingering. (ms. 19-20)’ \citep{Scholl:1999mi}

A key experimental tool used to investigate the existence of, and the principles underpinning, a system of object indexes is the Object Specific Preview Benefit.

Object indexes ... \begin{itemize} \item guide ongoing action (e.g.~visual tracking, reaching) \item influence how attention is allocated \citep{flombaum:2008_attentional} \item can be assigned in ways incompatible with beliefs and knowledge \citep[e.g.][]{Mitroff:2004pc, mitroff:2007_space} \item have behavioural and neural markers, in adults and infants \citep{richardson:2004_multimodal,kaufman:2005_oscillatory}. \item are subject to signature limits \citep[pp.~83--87]{carey:2009_origin} \item sometimes survive occlusion \citep{flombaum:2006_temporal} \end{itemize}

The interesting thing about object indexes is that a system of object indexes (at least one, maybe more) appears to underpin cognitive processes which are not strictly perceptual but also do not involve beliefs or knowledge states. While I can’t fully explain the evidence for this claim here, I do want to mention the one basic experimental tool that is used to investigate the existence of, and the principles underpinning, a system of object indexes which operates between perception and thought ...

Suppose you are shown a display involving eight stationary circles, like this one.

Four of these circles flash, indicating that you should track these circles.

All eight circles now begin to move around rapidly, and keep moving unpredictably for some time.

Then they stop and one of the circles flashes. Your task is to say whether the flashing circle is one you were supposed to track. Adults are good at this task \citep{pylyshyn:1988_tracking}, indicating that they can use at least four object indexes simultaneously.

(\emph{Aside.} That this experiment provides evidence for the existence of a system of object indexes has been challenged. See \citet[p.\ 59]{scholl:2009_what}: \begin{quote} `I suggest that what Pylyshyn’s (2004) experiments show is exactly what they intuitively seem to show: We can keep track of the targets in MOT, but not which one is which. [...] all of this seems easily explained [...] by the view that MOT is simply realized by split object-based attention to the MOT targets as a set.' \end{quote} It is surely right that the existence of MOT does not, all by itself, provide support for the existence of a system of object indexes. However, contra what Scholl seems to be suggesting here, the MOT paradigm can be adapated to provide such evidence. Thus, for instance, \citet{horowitz:2010_direction} show that, in a MOT paradigm, observers can report the direction of one or two targets without advance knowledge of which targets' directions they will be asked to report.)

Pylyshyn 2001, figure 6

object indexes can survive brief occlusion

modified from Scholl 2007, figure 4

object index assignments can conflict with knowledge states ...

Scholl 2007, figure 4

Consider this scenario in which a patterned square disappears behind the barrier; later a plain black ring emerges. You probably don't believe that they are the same object, but they probably do get assigned the same object index. Your beliefs and assignments of object indexes are inconsistent in this sense: the world cannot be such that both are correct.

Functions of object indexes:

✔ influence how attention is allocated

✔ guide ongoing actions (e.g. visual tracking, reaching)

✘ initiate purposive actions

The primary functions of object indexes include influencing the allocation of attention and perhaps guiding ongoing action. If this is right, it may be possible to explain anticipatory looking directly by appeal to the operations of object indexes. But the operations of object indexes cannot directly explain differences in how novel things are to an infant. And nor can the operations of object indexes directly explain why infants look longer at stimuli involving discrepancies in the physical behaviour of objects.

\emph{The CLSTX conjecture} Five-month-olds’ abilities to track occluded objects are not grounded on belief or knowledge: instead they are consequences of the operations of object indexes. \citep{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta}.

The CLSTX conjecture:

Five-month-olds’ abilities to track briefly unperceived objects

are not grounded on belief or knowledge:

instead

they are consequences of the operations of

a system of object indexes.

Leslie et al (1989); Scholl and Leslie (1999); Carey and Xu (2001)

(‘CLSTX’ stands for Carey-Leslie-Scholl-Tremoulet-Xu \citep[see][]{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta})

evidence

The CLSTX conjecture makes sense insofar as object indexes survive occlusion and enable tracking of objects by, for example, influencing ongoing actions, support anticipatory looking and modulate the allocation of attention.

But what is the evidence for it?

behavioural and neural indicators

behavioural: OSPB-like-effect (Richardson & Kirkham; note their caveats); neural Kaufmann, Csibra et al

If we consider six-month-olds, we can also find behavioural markers of object indexes in infants \citep{richardson:2004_multimodal} ...

... and there are is also a report of neural markers too \citep{kaufman:2005_oscillatory}.

The evidence we have so far gets us as far as saying, in effect, that someone capable of committing a crime was in the right place at the right time. Can we go beyond such circumstantial evidence?

signature limits

The key to doing this is to exploit signature limits.

A \emph{{signature limit} of a system} is a pattern of behaviour the system exhibits which is both defective given what the system is for and peculiar to that system.

\citet{carey:2009_origin} argues that what I am calling the signature limits of object indexes in adults are related to signature limits on infants’ abilities to track briefly occluded objects.

Scholl 2007, figure 4

To illustrate, a moment ago I mentioned that one signature limit of object indexes is that featural information sometimes fails to influence how objects are assigned in ways that seem quite dramatic.

Carey and Xu 2001, figure 3

There is evidence that, similarly, even 10-month-olds will sometimes ignore featural information in tracking occluded objects \citep{xu:1996_infants}.% \footnote{ This argument is complicated by evidence that infants around 10 months of age do not always fail to use featural information appropriately in representing objects as persisting \citep{wilcox:2002_infants}. In fact \citet{mccurry:2009_beyond} report evidence that even five-month-olds can make use of featural information in representing objects as persisting \citep[see also][]{wilcox:1999_object}. %they use a fringe and a reaching paradigm. NB the reaching is a problem for the simple interpretation of looking vs reaching! % NB: I think they are tapping into motor representations of affordances. Likewise, object indexes are not always updated in ways that amount to ignoring featural information \citep{hollingworth:2009_object,moore:2010_features}. It remains to be seen whether there is really an exact match between the signature limit on object indexes and the signature limit on four-month-olds’ abilities to represent objects as persisting. The hypothesis under consideration---that infants’ abilities to track briefly occluded objects depend on a system of object indexes like that which underpins multiple object tracking or object-specific preview benefits---is a bet on the match being exact. }

Xu and Carey 1996, figure 4

\emph{The CLSTX conjecture} Five-month-olds’ abilities to track occluded objects are not grounded on belief or knowledge: instead they are consequences of the operations of object indexes. \citep{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta}.

The CLSTX conjecture:

Five-month-olds’ abilities to track briefly unperceived objects

are not grounded on belief or knowledge:

instead

they are consequences of the operations of

a system of object indexes.

Leslie et al (1989); Scholl and Leslie (1999); Carey and Xu (2001)

(‘CLSTX’ stands for Carey-Leslie-Scholl-Tremoulet-Xu \citep[see][]{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta})

While I wouldn’t want to suggest that the evidence on siganture limits is decisive, I think it does motivate considering the hypothesis and its consequences. In what follows I will assume the hypothesis is true: infants’ abilities to track briefly occluded objects depend on a system of object indexes.

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

Charles & Rivera (2009)

How does help us with the puzzles?

Object indexes can survive occlusion ...

... but not the endarkening of a scence

But why do we get the opposite pattern with search measures?

So why do 5 month olds fail to manifest their ability to track briefly occluded objects by initiating searches for them after they have been fully occluded?

Because object indexes are independent of beliefs and do not by themselves support the initiation of action.

But we still have to explain this ...

Why do infants succeed in searching for momentarily endarkend objects? This finding seems to run directly against the CLSTX conjecture. After all, (1) object indexes do not survive endarkening; and (2) even if they did, they don’t enable you to initiate purposive actions. So the CLSTX conjecture provides two independent reasons to predict that 5-month-olds will \textbf{not} search for endarkened objects.

And yet they do. What does this mean?

Cardellicchio, Sinigaglia & Costantini, 2011 figure 1

Thinks about how adults represent objects. For adults, it is not just a matter of knowledge and object indexes. Objects are also represented motorically. But how an object is represented motorically depends on its affordances.

And representing an object motorically generally depends on its being one you could interact with.

Cardellicchio, Sinigaglia & Costantini, 2011 figure 2

[skip --- only included in case need for discussion]

Costantini et al, 2010 figure 1B

Importantly, putting a barrier between you and an object means that you can’t interact with it, and so the object is unlikely to be represented motorically.

And note that it doesn’t matter whether the barrier is an occluder; even a translucent barrier will prevent objects being represented motorically.

Costantini et al, 2010 figure 1B

[skip --- only included in case need for discussion]

	survive occlusion	survive endarkening
object index	✔	✘
motor representation	✘ (barrier)	✔

	occlusion	endarkening
violation-of-expectations	✔	✘
manual search	✘ (barrier)	✔

\emph{The CLSTX conjecture} Five-month-olds’ abilities to track occluded objects are not grounded on belief or knowledge: instead they are consequences of the operations of object indexes. \citep{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta}.

The CLSTX conjecture:

Five-month-olds’ abilities to track briefly unperceived objects

are not grounded on belief or knowledge:

instead

they are consequences of the operations of

a system of object indexes.

Leslie et al (1989); Scholl and Leslie (1999); Carey and Xu (2001)

(‘CLSTX’ stands for Carey-Leslie-Scholl-Tremoulet-Xu \citep[see][]{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta})

... and of a further, independent capacity to track physical objects which involves motor representations and processes.

This generates lots of predictions. For example, should be able to modulate object tracking of endarkened objects by interfering with, or boosting, motor cognition. But the same manipulations should not affect occlusion.

McCurry et al 2009, figure 1 (part)

Perfect way to deconfound barrier and occlusion: a screen you can’t see through but can reach through.

Irony: McCurry et al call their paper ‘beyond the search barrier’. But the whole point of an experiment like this should have been to deconfound occluders and barriers (one blocks vision, the other prevents action).

McCurry et al 2009, figure 1

Now consider an experiment with 5-month-olds using an occluder that is no barrier to ation. Instead the occluder is a fringed screen through which you can reach.

Here's the authors' description of their procedure. 'Once the ball came to rest at the right edge of the platform, the platform was pushed forward until the edge of the platform was directly in front of, and within easy reach of, the infant. In the second phase, the infant was allowed to search for 20 s. ' \citep{mccurry:2009_beyond}

McCurry et al found that 5 month old infants reach towards the cloth screen more often when a cube goes in and a ball comes out than when a cube goes in and a cube comes out. (I.e. cube-ball vs cube-cube.)

Why? On the CLSTX conjecture, this makes no sense. As we saw, a signature limit of object indexes is their disregard for featural information. Further, object indexes don’t enable you to initate purposive actions. So the CLSTX conjecture provides two reasons for making the incorrect prediction that infants will not search longer in the cube-ball condition than in the ball-ball condition.

But if you think about it in terms of motor representations, it makes perfect sense. Here is an occluder that is no barrier for action, so no obstacle to representing the objects motorically. And of course motor processes care deeply about the shapes of things, so we should expect a difference between the ball and the cube.

McCurry et al designed the perfect experiment to show that the CLSTX conjecture is not the whole story, and that 5-month-olds can represent unperceived objects motorically. But I don’t want to make too much of this because I’m interpreting their findings post hoc. Unfortunately this is not at all how they interpret their work. Instead, they write that ‘when task demands are minimal (successful performance requires only a direct reach through the fringe) young infants search reliably for hidden objects.’ But I don’t think anyone who has carefully considered Shinskey and Munakata’s work could be convinced by this idea. It’s a shame they weren’t thinking in terms of the Crude Picture of the Mind, but, you know, tant pis.

[skip] What should we predict? Cloth screen does not prevent action,\footnote{ ‘In the first familiarization trial, infants were shown the fringed-screen and were encouraged to reach through the fringe. If necessary, the experimenter gently guided the infant’s hand through the fringed-screen. Once the infant placed his or her hand through the fringed-screen twice, the trial ended.’ } so reaching should be possible. Further, if motor representations are responsible for the effect, the fact that the experiment requires sensitivity to featural information should not be an issue. (Further, a version of this task using violation of expectations may fail because featural information is critical.) And although these are very far from the terms in which they interpret their findings, this is exactly what McCurry et al 2009 found.

McCurry et al 2009, figure 2

\emph{The CLSTX conjecture} Five-month-olds’ abilities to track occluded objects are not grounded on belief or knowledge: instead they are consequences of the operations of object indexes. \citep{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta}.

The CLSTX conjecture:

Five-month-olds’ abilities to track briefly unperceived objects

are not grounded on belief or knowledge:

instead

they are consequences of the operations of

a system of object indexes.

Leslie et al (1989); Scholl and Leslie (1999); Carey and Xu (2001)

(‘CLSTX’ stands for Carey-Leslie-Scholl-Tremoulet-Xu \citep[see][]{Leslie:1998zk,Scholl:1999mi,Carey:2001ue,scholl:2007_objecta})

... and of a further, independent capacity to track physical objects which involves motor representations and processes.

This generates lots of predictions. For example, should be able to modulate object tracking of endarkened objects by interfering with, or boosting, motor cognition. But the same manipulations should not affect occlusion.

A Question:

What can object indexes explain?

[Q WILL BE: How does a difference in operations involving object indexes result in a difference in looking times?]

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

Charles & Rivera (2009)

How does help us with the puzzles?

Object indexes can survive occlusion but ...

Functions of object indexes:

✔ influence how attention is allocated

✔ guide ongoing actions (e.g. visual tracking, reaching)

✘ initiate purposive actions

The primary functions of object indexes include influencing the allocation of attention and perhaps guiding ongoing action. If this is right, it may be possible to explain anticipatory looking directly by appeal to the operations of object indexes. But the operations of object indexes cannot directly explain differences in how novel things are to an infant. And nor can the operations of object indexes directly explain why infants look longer at stimuli involving discrepancies in the physical behaviour of objects.

Wynn 1992, fig 1 (part)

We know that infants are likely to maintain object indexes for the two mice while they are occluded. Accordingly, when the screen drops in the condition labelled ‘impossible outcome’, there is an interruption to the normal operation of object indexes: infants have assigned two object indexes but there is only one object. But why does this cause infants to look longer at in the ‘impossible outcome’ condition than in the ‘possible outcome’ condition? How does a difference in operations involving object indexes result in a difference in looking times?

object index operations

↓

? ? ? metacognitive feelings

↓

patterns in looking durations

So those who, like me, are impressed by the evidence for the hypothesis that four- and five-month-olds’ abilities to track occluded objects are underpinned by the operations of a system of object indexes are left with a question. The question is, What links the operations of object indexes to patterns in looking duration?

I’ve just argued that it can’t be beliefs or knowledge states. So what is it?

The sense of agency is far from the only metacognitive feeling. Consider a second illustration ... familiarity

Here is a face that I hope will seems familiar to most people. When you see this face, you have a feeling of familiarity. This feeling of familiarity is not just a matter of belief: even if you know for sure that you have never encountered the person depicted here (and trust me, you haven’t), the feeling of familiarity will persist. Nor is the feeling a matter of perceptual experience: you can’t perceptually experience familiarity any more than you can perceptually experience electricity.

What causes feelings of familiarity? Not familiarity as such, it turns out. Instead they are caused by the ease with which you can process the features of a face relative to difficulty of identifying the person. Roughly, the greater the discrepancy between fluency of processing and difficulty of identification, the stronger the feeling of familiarity.

So what is this feeling of familiarity?

First, it phenomenal. It is an aspect of the phenomenal character of some experience associated with acting. So we can call it a feeling.

Second, it is metacognitive in the sense that it’s normal causes include processes which monitor fluency of processing. So we can call it a \emph{metacognitive feeling}.% \footnote{Compare \citet[p.~310]{dokic:2012_seeds}: ‘the causal antecedents of noetic feelings can be said to be metacognitive insofar as they involve implicit monitoring mechanisms that are sensitive to non-intentional properties of first-order cognitive processes.’}

Third, it does not necessarily give rise to beliefs. As I mentioned, the feeling is not lessen even if you refuse to believe, as you should, that this person is actually familiar to you.

(The face is a composite of Bush and Obama. It is chosen to illustrate that the feeling of familiarity is not a consequence of how familiar things actually are; instead it may be a consequnece of the degree of fluency with which unconscious processes can identify perceived items \citep{Whittlesea:1993xk,Whittlesea:1998qj}. Learning a grammar can also generate feelings of familiarity. Subjects who have implicitly learned an artificial grammar report feelings of familiarity when they encounter novel stimuli that are part of the learnt grammar \citep{scott:2008_familiarity}. They are also not doomed to treat feelings of familiarity as being about actual familiarity: instead subjects can use feeling of familiarity in deciding whether a stimulus is from that grammar \citep{Wan:2008_familiarity}.)

I could go on to mention the feeling you have when someone’s eyes are boring into your back, or the feeling that a name is on the tip of your tongue. But let me focus just on the feelings associated with electricity and with familiarity. These feelings are paradigm cases of metacognitive feeling.

What is a metacognitive feeling? I think it’s a sensation. To illustrate,

contrast two sensory encounters with this wire. In the first you visually experience the wire as having a certain shape. In the second you receive an electric shock from the wire without seeing or touching it.% \footnote{This illustration is borrowed from Campbell (2002: 133–4); I use it to support a claim weaker than his.} The first sensory encounter involves perceptual experience as of a property of the wire whereas, intuitively, the second does not. I take this intuition to be correct.% \footnote{ Notice that the intuition is not that the shock involves no perceptual experience at all, only that the shock does not involve perceptual experience as of any property of the wire. Notice also that the intuition concerns what a perceptual experience is as of, and not directly what is represented in perception. The relation between these two is arguably not straightforward (compare, e.g., \citet[p.~28]{Shoemaker:1994el} or \citet[pp.~50--2]{Chalmers:2006xq} on distinguishing representational from phenomenal content). }

The intuition is potentially revealing because the electric shock involves rich phenomenology, and its particular phenomenal character depends in part on properties of its cause (changes in the strength of the electric current would have resulted in an encounter with different phenomenal character). So there are sensory encounters which, despite having phenomenal characters that depend in part on which properties are encountered, are not perceptual experiences as of those properties.

Let me give you two more illustrations [bushObama and Wynn’s magic mice]. ...

All three examples (the feelings of magic, of electricity and of familiarity) show that:

There are aspects of the overall phenomenal character of experiences which their subjects take to be informative about things that are only distantly related (if at all) to the things that those experiences intentionally relate the subject to.

To illustrate, having a feeling of familiarity is not a matter of standing in any intentional relation to the property of familiarity, but it is something that we can interpret as informative about famility.

Metacognitive feelings are these aspects of experience.

Why accept this? You cannot perceive familiarity or agency any more than you can perceive electricity. Perceptual processes do not reach far back into your past, nor are they concerned with questions about whether you are the agent of an action. So to think that metacognitive feelings intentionally relate you to facts about familiarity or agency requires postulating a novel kind of sensory process, some kind of inner or bodily sense. While justification for postulating a novel inner sense may ultimately be discovered, I don’t think there is currently anything to justify this.

[EITHER] To see why we are not justified in postulating a novel inner sense, it is worth recalling Reid’s theory of sensations. [OR] But this is right, why do metacognitive feelings invite judgements? Why does the feeling of familiarity even so much as nudge you to judge that the face photographed here is familiar to you? (This is roughly \citet{dokic:2012_seeds}’s question.)

[Key point to stress there is just that metacognitive feelings are not intentional states, they are not representations, they have no content. [Or if they do have content, it’s not related to the things we take them to be associated with, like familiarity or electricity.] They are blank sensations. Compare the sensation associated with an electrical shock. It’s not a perception of electricity.]

Metacognitive feelings

can be thought of as

sensations.

metacognitive feelings can be thought of as sensations in approximately Reid’s sense.% \footnote{ \citet{Reid:1785cj,Reid:1785nz}. Even if you don’t believe that there are sensations in Reid’s sense, thinking of metacognitive feelings as if they were sensations will serve to illustrate their characteristic features. The main points that follow are consistent with several different ways of thinking about metacognitive feelings. For instance, you might take the view that what I am calling metacognitive feelings are perceptual experiences of the body or of bodily reactions, or that they involve some kind of cognitive phenomenology. The essential claim is just that the metacognitive feelings associated with the operations of object indexes are not constituted by states which involve intentional relations to any of the things which are assigned an object index. }

Sensations are

monadic properties of perceptual experiences
individuated by their normal causes
(so they do not involve an intentional relation)
which alter the overall phenomenal character of those experiences
in ways not determined by the experiences’ contents.

Sensations are: \begin{enumerate} \item monadic properties of events, specifically perceptual experiences, \item individuated by their normal causes% %{Tye, 1984 #1744@204} ---in the case of feelings of familiarity, its normal cause is ease of processing \item which alter the overall phenomenal character of those experiences \item in ways not determined by the experiences’ contents (so two perceptual experiences can have the same content while one has a sensational property which the other lacks). \end{enumerate}

metacognitive feelings trigger beliefs only via associations.

An important consequence is that metacognitive feelings can lead to beliefs only via associations or further beliefs. They are signs which need to be interpreted by their subjects (\citealp[Essay~II, Chap.~16, p.~228]{Reid:1785cj} \citealp[Chap.~VI sect.~III, pp.~164–5]{Reid:1785nz}). Let me explain.

As a scientist, you can pick out the feeling of familiarity as that metacognitive feeling which is normally caused by the degree to which certain processes are fluent. But as the subject of who has that metacognitive feeling, you do not necessarily know what its typical causes are. This is something you have to work out in whatever ways you work out the causes of any other type of event.

(Contrast metacognitive feelings with perceptual experiences. Having a perceptual experience of, say, a wire’s shape, involves standing in an intentional relation to the wire’s shape; and the phenomenal character of this perceptual experience is specified by this intentional relation.% \footnote{ Compare \citet[p.~380]{Martin:2002yx}: ‘I attend to what it is like for me to inspect the lavender bush through perceptually attending to the bush itself.’ And \citet[p.~211]{byrne:2001_intentionalism} ‘subject can only discover the phenomenal character of her experience by attending to the world ... as her experience represents it.’ } Such perceptual experiences are often held to reveal the wire’s shape to the subject and so lead directly to beliefs.% \footnote{ Compare \citet[p.~222]{Johnston:1992zb}: ‘[j]ustified belief … is available simply on the basis of visual perception’; \citet[p.~143–4]{Tye:1995oa}: ‘Phenomenal character “stands ready … to make a direct impact on beliefs’; and \citet[p.~291]{Smith:2001iz}: ‘[p]erceptual experiences are … intrinsically … belief-inducing.’ })

(By contrast, having a metacognitive feeling concerning familiarity or an physical object’s path does not involve standing in any intentional relation to these things. The metacognitive feeling is individuated by its normal causes, rather than by any intentional relation. And a metacognitive feeling leads to belief, if at all, only indirectly. For learning is required in order for the subject to come to a view on what tends to cause the metacognitive feeling.)

metacognitive feelings have been quite widely neglected in philosophy and developmental psychology. They are a means by which cognitive processes enable perceivers to acquire dispositions to form beliefs about objects’ properties which are reliably true. metacognitive feelings provide a low-cost but efficient bridge between non-conscious cognitive processes and conscious reasoning.

This, anyway, is why I think that

metacognitive feelings

Thereare aspects of the overall phenomenal character of experiences which their subjects take to be informative about things that are only distantly related (if at all) to the things that those experiences intentionally relate the subject to.

Wynn 1992, fig 1 (part)

What is a metacognitive feeling? Consider a third (and final) illustration.

Recall this situation. Suppose you have seen it a hundred times before, so you know just what to expect. Still, the tendancy to expect two objects is on some level barely diminished, and event in which a single object is revealled is liable to feel magical in some small way. This feeling of magic is a metacognitive feeling.

feeling of surprise

There is a feeling of surprise which has features characteristic metacognitive feelings.

‘the intensity of felt surprise is [...] influenced by [...]
the degree of the event’s interference with ongoing mental activity’

Reisenzein et al, 2000 p. 271; cf. Touroutoglou & Efklides, 2010

In particular,

‘the intensity of felt surprise is not only influenced by the unexpectedness of the surprising event, but also by the degree of the event’s interference with ongoing mental activity, [...] the effect of unexpectedness on surprise is [...] partly mediated by mental interference’ \citep[p.~271]{reisenzein2000subjective}

That is, the feeling of surprise is a sensational consequence of mental interference. (This can be tested by increasing cognitive load: this intensifies feelings of surprise without, of course, making the events themselves more suprirsing. But see \citep{reisenzein:2017_cognitiveevolutionary} for an alternative interpretation of such findings.)

So whereas the feelings of agency and familiarity are both consequences of unexpected fluency of processing, the feeling of surprise is supposed to be the opposite: it is a consequence of unexpected interference in processes.

\footnote{% An alterantive is proposed by \citet[p.~79]{foster:2015_whya}: ‘the MEB theory of surprise posits that: Experienced surprise is a metacognitive assessment of the cognitive work carried out to explain an outcome. Very surprising events are those that are difficult to explain, while less surprising events are those which are easier to explain.’ \citet{foster:2015_whya} is about reactions to reading about something unexpected, whereas \citet{reisenzein2000subjective} measures how people experience unexpected events (changes to stimuli while solving a problem). The latter is much closer to what I’m after. }

object index operations

↓

? ? ? metacognitive feelings

↓

patterns in looking durations

So my question was how the operations of object indexes might explain patterns of looking duration in habituation and violation-of-expectation experiments.

My guess is that some operations of object indexes give rise to metacognitive feelings, which in turn influence looking durations.

Objection

If object index operations produce metacognitive feelings,

wouldn’t these generate knowledge about object locations?

(And so generate the incorrect predictions that flow from ascribing knowledge of object locations?)

Reply: (a) metacognitive feelings are of surprise, not of particular locations. The feelings do not specify anything about what caused them; (b) in any case, the feelings do not necessarily trigger beliefs at all ...

You can choose to interpret the feeling differently. You are not presented with familiarity in the way that you are presented with, say, circularity.

object index operations

↓

? ? ? metacognitive feelings

↓

patterns in looking durations

So my question was how the operations of object indexes might explain patterns of looking duration in habituation and violation-of-expectation experiments.

My guess is that some operations of object indexes give rise to metacognitive feelings, which in turn influence looking durations.

conclusion

I started this talk by posing two related questions ...

My first questino was, What is the nature of infants’ earliest cognition of physical objects?

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

I have questioned this ...

I think the Crude Picture of the Mind is surprisingly useful in getting a fix on developmental discrepancies, particularly compared to theories which postulate either knowledge (incorrect predictions) or core knowledge (no predictions).

Contra the view suggested by Carey, it seems that, at least in the domain of physical objects, there is no need to postulate ‘core knowledge’ as something distinct from the 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 ...)

metacognitive feelings
(connect the motoric and perceptual to knowledge)

I also think the importance of metacognitive feelings may have been overlooked.

When it comes to explaining how different bits of the mind interact, or how knowledge emerges in development, we need metacognitive feelings because, aside from effects on behaviour and control of attention, \textbf{it is only metacognitive feelings that connect the motoric and perceptual to knowledge}.

Metacognitive feelings have been quite widely neglected in philosophy and developmental psychology. They are a means by which cognitive processes enable perceivers to acquire dispositions to form beliefs about objects’ properties which are reliably true. Metacognitive feelings provide a low-cost but efficient bridge between non-conscious cognitive processes and conscious reasoning.

end

Leibniz’ view : I think he is wrong because object indexes + metacognitive feelings do not amount to notions and doctrines, nor to they ‘rouse up’ notions and doctrines. There is a huge step from object indexes + metacognitive feelings to knowledge proper.

‘the soul inherently contains the sources of various notions and doctrines which external objects merely rouse up on suitable occasions’

Leibniz (1996, p. 48)

\citep[p.\ 48]{Leibniz:1996bl}

The other question I mentioned at the start of this talk was, How do you get from these early forms of cognition to knowledge of simple facts about particular physical objects?

Q2 How do you get from these early forms of cognition to knowledge of simple facts about particular physical objects?

The Assumption of Representational Connections

The transition involves operations on the contents of representations, which transform them into (components of) the contents of knowledge states.

On any standard view,

\emph{The Assumption of Representational Connections}: the transition from early forms of cognition (core knowledge?) to knowledge proper involves operations on the contents of representations, which transform them into (components of) the contents of knowledge states.

Metacognitive feelings are \emph{intentional isolators}: that is, they are states which can causally link representations but have no intentional objects.

Conjecture

Let me offer you a conjecture which I have not argued for but which is perhaps tempting given the difficulty of identifying ways in which processes interact ...

Only metacognitive feelings
(and behaviours, and other intentional isolators)
connect early-developing processes for tracking objects, causes, actions and minds
to the epistemic.

Metacognitive feelings have been quite widely neglected in philosophy and developmental psychology. But they are important as a means by which cognitive processes enable thinkers to acquire dispositions to form reliably true beliefs about objects. More generally, metacognitive feelings provide a low-cost but efficient link from otherwise mostly inaccessible cognitive processes to thought. When it comes to explaining how different bits of the mind interact, and how knowledge emerges in development, we need metacognitive feelings because {it is only metacognitive feelings (and behaviours and other intentional isolators) that connect the motoric and perceptual to knowledge}. And this is a reason for thinking that cognitive development is a process of rediscovery.

And,

Development is rediscovery.

[Key point is that since metacognitive feelings don’t have [relevant] content, direct representational connections are impossible.

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