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\title {Social Cognition \\ Lecture 02}
 
\maketitle
 

Lecture 02:

Social Cognition

\def \ititle {Lecture 02}
\def \isubtitle {Social Cognition}
\begin{center}
{\Large
\textbf{\ititle}: \isubtitle
}
 
\iemail %
\end{center}
 
\section{Objections to the Intentional Stance}
 
\section{Objections to the Intentional Stance}
A fundamental project in theorising about social cognition is to provide an account radical interpretation*. An account of radical interpretation* is an account of how you could in principle infer facts about actions and mental states from non-mental evidence.

radical interpretation*

Infer The Mind from The Evidence

The Mind: facts about actions, desires, beliefs, emotions, perspectives ...

The Evidence: facts about events and states of affairs that could be known without knowing what any particular individual believes, desires, intends, ...

Dennett’s account of the intentional strategy is (or can be usefully misinterpreted as) an account of radical interpretation*. Does it succeed?
Does the Intentional Stance actually describe how it would be possible, even in principle, to infer facts about minds and actions from evidence that can be described without knowing anything about the particular actions, beliefs, desires and other mental states of any individual?

‘the intentional stance ...

‘first you decide to treat the object whose behavior is to be predicted as a rational agent;

‘then you figure out what beliefs that agent ought to have , given its place in the world and its purpose.

‘Then you figure out what desires it ought to have, on the same considerations,

‘and finally you predict that this rational agent will act to further its goals in the light of its beliefs’

Dennett (1987, 17)

Recall the intentional stance ...
This fits the bill as a theory of radical interpretation* insofar as it describes a strategy which presupposes no knowledge of the object’s particular thoughts or actions.
But does the Intentional Strategy give us the truth about radical interpretation*?
Suppose you are faced with the choice of eating one of two things ...

EITHER:

actual food, tiny bit mouldy

OR:

poison that looks like food

Suppose someone is faced with a choice between these two things. What will she choose? Let’s apply the Intentional Stance to make a prediction.
The Intentional Stance tells us to attribute a desire for food. And to attribute beliefs the agent ought to have, which in this case are the beliefs that this stuff is poison and that this stuff is food.
We then assume rationality in order to predict an action: she will choose the food, not the poison.
Now what happens when we observe that our prediction is wrong and that she chooses the poison which looks like food?
It’s just here that her behaviour is informative, on the Intentional Stance. The failure of our prediction tells us that we are wrong about something.
But what are we wrong about? The belief, the desire or the rationality?

Error of

- belief

It could be that we are wrong about your belief: perhaps you falsely believe that the poison is nutritious, for example.

- desire

Alternatively, we could be mistaken in supposing that you desire to eat well and enjoy a long, healthy life.

- rationality

Finally, we may be wrong in assuming that your actions are rational given your desires and belief. We may be correct in thinking you believe that the burger is poison and want to eat well. But perhaps you are nevertheless somehow drawn to eat it.
Of course we cannot hope to work out what the error is on the basis of just this observation. But we can sometimes distinguish false belief (this poison is food) from inappropriate desire (to eat something poisonous) from a faulty link between beliefs-desire pairs to actions.
This point generalises ...

The Intentional Strategy sometimes or always results in incorrect predictions when

i. people have false beliefs;

ii. people have ‘incorrect’ desires; and

iii. people’s actions are not rational given their beliefs and desires.

When it generates incorrect predictions, the Intentional Strategy does not enable us to identify whether this is due to belief, desire or rationality.

∴ The Intentional Strategy provides no way for us to identify false beliefs, ‘incorrect’ desires or failures of rationality.

But much of the importance of social cognition arises from the ways in which our beliefs, desires and other mental states differ, and from the fact that we often fail to be fully rational.
But what we want from a theory of interpretation is an explanation of how the available evidence ever enables us to distinguish between different kinds of errors. And as far as I can tell Dennett has not attempted to supply such a theory.

Objection 1

The Intentional Stance provides
no way to identify
false beliefs, ‘incorrect’ desires or failures of rationality.

This is linked to a more general problem for Dennett ...
On the intentional strategy,

The Intentional Strategy

What enables an interpreter to distinguish your actions, beliefs, desires, feelings and other mental states from anybody else’s?

On the intentional strategy as Dennett describes it, it basically comes down to two things:

- your location in space

- your biological needs

So I think it is clearly a mistake to say that the Intentional Strategy is an account of radical interpretation*. Minimally, an account of radical interpretation* needs to explain how the interpreter can identify the distinctive actions, beliefs, desires and other mental states of an individual. The Intentional Strategy appears fundamentally unsuited to this purpose because the Intentional Strategy involves making very little use of evidence.

Objection 1

The Intentional Stance provides
no way to identify
false beliefs, ‘incorrect’ desires or failures of rationality.

Objection 2

The Intentional Stance provides
no adequate way to
distinguish me from you.

How clear are these objections? Are they good objections? Are there further objections that we should consider?
[my view] These are not deep objections to Dennett. You might say, his theory is fine as far as it goes; it was only meant to cover a couple of basic principles, leaving much of the project for future development.
I accept this evaluation of the objections objections. But it is striking that, as far as I know, almost no one has yet taken up the challenge of completing, or furthering, the project of explaining how interpretation works for languageless animals.
Before going further, let me explain why I think it would be good to have more insight into how interpretation works ...

But why are we studying the Intentional Strategy at all?

[At this point, I don’t think we are really in a good position to evaluate Objecions 1 & 2 to the (misinterpreted) Intentional Strategy. This is because we have yet to clearly explain what we want from it. [PREVIEW: we want a theory of radical interpretation from it, one that provides a (correct) computational description of social cognition.].]
Easy: because it’s the simplest theory of radical interpretation* I know of.

radical interpretation*

Infer The Mind from The Evidence

The Mind: facts about actions, desires, beliefs, emotions, perspectives ...

The Evidence: facts about events and states of affairs that could be known without knowing what any particular individual believes, desires, intends, ...

But why are we studying radical interpretation*?

I’m so glad you asked. Let me try to say again, in a slightly different way, what this modules is about ...
 

The Topic Re-introduced

 
\section{The Topic Re-introduced}
 
\section{The Topic Re-introduced}
The central question for the course is,

What makes others’ minds and actions intelligible to us?

The idea is very simple. We know much about others’ mental lives, their intentional actions, desires, dreams and fears; we also know much about what their words mean, about their significant pauses and facial gestures. What makes these things intelligible to us?
Since I wrote the module, I came to realise that I phrased the question badly.
Who is ‘us’? I’m mostly going to focus on typically developing adult humans, but we will also discuss nonhumans, and infants; we will probably not discuss autistic spectrum disorder and other cases which involve impaired social cognition.
But I realised after I submitted the module proposal that I should have formluated the question slightly differently, so as to avoid the question of who ‘us’ is. What matters for this course is just that, as far as we know, minds and actions are intelligible to *some* others.

What makes
minds and actions
intelligible cognizable to others?

I’m still not happy that I have the question optimally formulated. Maybe instead of ‘intelligible’, I should have said ‘cognizable’.
The question I am asking is essentially one the philosopher Donald Davidson spent most of his career asking ...

‘I want to know what it is about propositional thought---our beliefs, desires, intentions and speech---that makes it intelligible to others.’

\citep[p.~14]{Davidson:1995nl}

Davidson (1995, 14)

The difference is just that whereas Davidson focusses on propositional thought, one theme of my lectures will be that we need to consider a wider range of mental phenomena, including emotional processes, attention and goal-directed action.
But how does any of this relate to social cognition? [PLAN: link this question about what makes others minds and actions intelligible back to social cognition via the idea of radical interpretation* as a computational description.]
Recall our working definition of social cognition ...

Social cognition:

cognition of
others’ actions and mental states
in relation to social functioning.

So my question, What makes minds and actions intelligible to others? is a fundamental question about social cognition. The question requires us to provide an account of how, in principle, social cognition is possible.
Importantly, it is not a question about how we actually track others’ actions or mental states. The question is how we could do so.
So I was asking, Why are we studying Dennett’s Intentional Strategy? And my answer is this. Our topic is social cognition, cognition of others’ actions and mental states. A fundamental question about social cognition is, What makes minds and actions cognizable to others? To answer this question we need a theory of radical interpretation*. And Dennett’s Intentional Strategy is--or can be (mis)interpreted--as the an extremely simple theory of radical interpretation.
With this in mind, let me return to the two objections ...
Recall the objections to the Intentional Stance (mis)construed as a theory of radical interpretation*.

Objection 1

The Intentional Stance provides
no way to identify
false beliefs, ‘incorrect’ desires or failures of rationality.

Objection 2

The Intentional Stance provides
no adequate way to
distinguish me from you.

Now we are in a position to see why these are objections. If we want the Intentional Strategy to provide a computational description of social cognition, then it needs to describe the nature of capacities we have.
Since we can identify false beliefs and distinguish one person from another, the Intentional Stance would need to explain how we could in principle do that. It’s failure to do so shows that it is not the truth, or at least not the whole truth, about social cognition.
Analogy: A computational description for a GPS receiver that can only tell you where it is when it is in the places it ought to be. (So it’s no good if you get lost.)

1. Humans can sometimes identify false beliefs, ‘incorrect’ desires or failures of rationality.

BUT

2. The Intentional Stance provides no way to identify false beliefs, ‘incorrect’ desires or failures of rationality.

3. The Intentional Stance does not provide a correct computational description of human social cognition.

Recall the objections to the Intentional Stance (mis)construed as a theory of radical interpretation*.

Objection 1

The Intentional Stance provides
no way to identify
false beliefs, ‘incorrect’ desires or failures of rationality.

Objection 2

The Intentional Stance provides
no adequate way to
distinguish me from you.

1. Humans can distinguish each others desires in ways unrelated to their purpose and place in the world.

BUT

2. The Intentional Stance provides no adequate way to distinguish me from you.

3. The Intentional Stance does not provide a correct computational description of human social cognition.

Objection 1

The Intentional Stance provides
no way to identify
false beliefs, ‘incorrect’ desires or failures of rationality.

Objection 2

The Intentional Stance provides
no adequate way to
distinguish me from you.

conclusion so far

What makes minds and actions cognizable to others?

A theory of radical interpretation* would answer this question.

Dennett’s ‘Intentional Strategy’ can be (mis)interpreted as a theory of radical interpretation* ...

... but it faces insurmountable objections.

We must therefore look elsewhere for a theory of radical interpretation*.

Here’s why I worry that this module is just too wild. Look in any textbook on social cognition. I bet you will find no mention of radical interpretation* at all. Nor will you find anything resembling an attempt to provide a computational description of social cognition.
Number of researchers I have convinced that constructing a theory of radical interpretation* would be a contribution to research on social cognition: 0.
Peer-reviewed publications in which I have explained why constructing a theory of radical interpretation would be a contribution to research on social cognition: 0.

core project: construct a theory of radical interpretation*

Way forward for constructing a theory of radical interpretation*?

--- link observations to ascriptions

Dennett’s Intentional Strategy makes almost no use of The Evidence.

--- break it down (multiple processessocial cognition may involve multiple, largely independent processes: perception, motoric, emotional)

--- not just observation: interaction too

Let’s start by thinking about a possible role for perception in social cognition ....
 

Perceiving Expressions of Emotion: A Challenge

 
\section{Perceiving Expressions of Emotion: A Challenge }
 
\section{Perceiving Expressions of Emotion: A Challenge }

How do you know about it?it = this penit = this joy

perceive indicator, infer its presence

- vs -

perceive it

[ but perceiving is inferring ]

Here are three ways of knowing: inference, testimony and perception.
Where ‘it’ is an ordinary physical object like my favourite pen, each of these three identifies a process by which knowledge could be acquired.
(This is not to say that talk about reasoning invariably picks out a process (cf Alvarez), just that there is a process.)
There seems to be a clear contrast the first and last ways of coming to know about it. (Philosophers debate about whether the first and second are genuinely different routes to knowledge.)
Even if, as do I, you think perception involves inference-like processes, there is still a contrast between inferring and perceiving.
For instance, suppose you know that I am all but inseparable from my favourite pen. Then when you see me arrive you can infer that my pen is here too. Contrast this with simply seeing my pen on the table. In one case we see something other than the pen, namely me, and inferring that the pen is here; in the other case you are seeing the pen itself.
This is the contrast I need in what follows.
Are mental states the kinds of thing we can come to know about through perceiving them? I will focus on emotions like joy.

Aviezer et al (2012, figure 2A3)

[not relevant yet:] ‘(3) a losing face on a winning body’
Emotions are sometimes expressed bodily and vocally. Here is someone who has just won or lost a tennis match, so is feeling joy or anger. Maybe you can tell which?
Here is a natural thought: Bodily and vocal expressions of emotion enable us to perceptually experience the expressed emotions.
This natural thought fits with ordinary talk about mental states. Imagine yourself at a tennis match. Reporting the event afterwards, you might say that you saw his ecstacy at winning. It might seem that his ecstacy is as plainly visible as the hair on his head.

‘We sometimes see aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

McNeill (2012, p. 573)

‘We sometimes see aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

McNeill (2012, p. 573)

\citet[p.\ 573]{mcneill:2012_embodiment}: ‘We sometimes {see} aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

challenge

Evidence?

verbal reports and ratings? No!

(Scholl & Tremoulet 2000; Schlottman 2006)

There are scientists and philosophers who have placed a lot of weight on verbal reports. They are satisfied that if people use mental state terms to describe what they perceive, then they perceive those mental states. But I think this can’t be right.
Go back to the tennis match. Reporting the event afterwards you might say not only that you saw his ecstacy but also that you saw him win. I take it you can't literally perceptually experience winning or losing in the sense that, arguably, you can perceptually experience movement or changes in colour. After all, winning or loosing is a matter of rules and conventions.
So we can’t straightforwardly take what people say as a guide to what they perceive.
Here you might object that we can perceptually experience things like winning or losing, so there is no reason to question verbal reports.
But note that taking this line amounts to rejecting the claim I started with.

contrast:

perceive indicator, infer its presence

- vs -

perceive it

I claimed that there is a contrast between seeing an indicator and inferring the presence of an object
If there is a contrast here, what we colloquially call seeing someone win must be a case of perceiving indicators and inferring winning. So to say that we can straightforwardly infer that people perceive emotions from their verbal reports is to reject the existence of the very contrast that allows us to make sense of the question.

‘We sometimes see aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

McNeill (2012, p. 573)

challenge

Evidence?

 

Do We Really Need Evidence?

 
\section{Do We Really Need Evidence?}
 
\section{Do We Really Need Evidence?}

‘Consider furniture that looks Swedish ... or the properties of looking sad or looking delighted’

‘One can explain the apparently perceptual phenomenon thus. There is some kind such that the thing or person appears to be of that kind, and the person judges that things of that kind are (say) Swedish people [sic].’

‘But such a division ... does not ... fit the case of perception of the expression of an emotion. ... There is no kind described without reference to the emotions of which one can say that the facial expression appears to be of that kind and it is merely an additional judgement on the part of the person that people looking that way are sad.’

\citep[p.~66]{Peacocke:2004ke}
I’m not sure exactly what Peacocke takes from this (because I haven’t read enough of his book), but Joel Smith (2013) treats this claim as sufficient to establish ‘the fact that these cases [looking Swedish/excited and looking happy] are different with respect to visual presence’. (He seems to step back from this in the conclusion of Smith (2013, p. 18): ‘I have not offered a robust defence of the phenomenological claims set out in §2, motivating them rather on intuitive grounds’)
‘the fact that these cases [looking Swedish/excited and looking happy] are different with respect to visual presence’. \citep[p.~5]{smith:2013_phenomenology}
‘I have not offered a robust defence of the phenomenological claims set out in §2, motivating them rather on intuitive grounds’ \citep[p.~18]{smith:2013_phenomenology}
But I find this baffling. How do we know that ‘There is no kind described without reference to the emotions of which one can say that the facial expression appears to be of that kind and it is merely an additional judgement on the part of the person that people looking that way are sad’? Consider how difficult it would be to specify a kind that Swedish furniture appears to have that can be described without reference to Sweden.
With respect to the question I started with (involving the contrast between perceiving an indicator plus inferring and simply perceiving), Peacocke seems to be saying that the answer is obvious. Why does he think this? And why does Smith?

Peacocke (2004, 66)

L: For any object O and functional property F, if the perceptual anticipations in one’s perception of O ‘latch onto’ the functional role definitive of F, then one perceives O as being F.

\citep[p.~741]{smith:2010_seeing}

To explain the sense in which the nonvisible parts of objects, such as the back of a tomato, can be visually present, Smith follows many in suggesting that perceptual states can in some sense contain anticipations of what would happen if, say, an object were rotated or if one moved around it.

‘If we define mental state M as that property one has if one will behave in way B given input I, and [...] one perceptually anticipates that if I occurs then one will perceive B, then one’s perceptual states ‘latch onto’ property M’

\citep[p.~741]{smith:2010_seeing}
Suppose we accept this. Then the claim that we can perceptually experience Syliva’s happiness is the claim that perceptual states ‘latch onto’ Syliva’s happieness. But can they?

Do any perceptual states latch onto happiness?

‘This is a matter open to empirical and phenomenological confirmation ... [I]t seems likely to me’

\citep[p.~742]{smith:2010_seeing}
So we shouldn’t think of Smith as showing that we can or cannot perceptually experience happiness; instead we should think of him as explaining what it would be for emotions such as happiness to be perceptually experienced, leaving open the question of whether or not they are.

Smith (2010, 741-2)

 

Categorical Perception & Emotion

 
\section{Categorical Perception & Emotion}
 
\section{Categorical Perception & Emotion}

2.5B

7.5BG

2.5BG

Categorical perception is perhaps most easily understood from the case of colour.
Let me start with something quite basic. Here are three patches of colour. The patches are all different colours, but the two leftmost are both the same colour---they are both blue. This sounds contradictory but isn't. In one case we're talking about the particular colours of things; in the other case we're talking about colour category.
To claim that there is categorical perception is, very roughly and to a first approximation, to claim that perceptual processes are concerned not only with the particular colours of things but also with categories of colour like blue and red.
This is not a definition, only a very rough starting point.
We can go slightly further with an operational definition of categorical perception ...
[For later: colour is doubly relevant because there's been serious debate about whether it's possible to perceive categorical colour properties despite copious verbal reports. This case shows how evidence can bear on questions about phenomenology, although I won’t be talking about that here (probably).]

fix initial system of categories

measure disciminatory responses

observe between- vs within-category differences

exclude non-cognitive explanations for the differences

greater discrimination between than within catgeories indicated that the inital system of categories may be having some influence on whatever underpins the responses.
Do any perceptual processes in humans discriminate stimuli according to the expressions of emotion they involve? That is, do humans have \emph{categorical perception} of expressions of emotion?
Assume that we as theorists have a system which allows us to categorise static pictures of faces and other stimuli according to which emotion we think they are expressing: some faces are happy, others fearful, and so on. From five months of age, or possibly much earlier \citep{field:1982_discrimination}, through to adulthood, humans are better at distinguishing faces when they differ with respect to these categories than when they do not \citep{Etcoff:1992zd,Gelder:1997bf,Bornstein:2003vq,Kotsoni:2001ph,cheal:2011_categorical,hoonhorst:2011_categoricala}.
To illustrate, consider these pictures of faces. The idea is this.
With respect to all features apart from the expression of emotion, each face picture differs from its neighbours no more than any other picture differs from its neighbours.
Most neighbouring pairs of face pictures would be relatively hard to distinguish,
especially if they were not presented side-by-side.
But most people find one pair of neighbouring face pictures relatively easy to distinguish---you may notice this yourself.
What underlies these patterns of discrimination? Several possibilities that would render them uninteresting for our purposes can be ruled out. The patterns of discrimination do not appear to be an artefact of linguistic labels (\citealp{sauter:2011_categorical}; see also \citealp{laukka:2005_categorical}, p.\ 291),% % \footnote{ Puzzlingly, experiments by \citet{fugate:2010_reading} using photos of chimpanzee faces with human subjects are sometimes cited as evidence that categorical perception of expressions of emotion depends on, or can be modulated by, the use of verbal labels for stimuli (e.g.\ \citealp[p.\ 288]{barrett:2011_context}; \citealp[p.\ 315]{gendron:2012_emotion}). Caution is needed in interpreting these findings given that there may be differences in the ways humans process human and chimpanzee faces. In fact, what \citeauthor{fugate:2010_reading}'s findings show may be simply that `human viewers do not show [categorical perception] for the chimpanzee facial configurations used in their study' \citep[p.\ 1482]{sauter:2011_categorical}. } % nor of the particular choices subjects in these experiments are presented with \citep{bimler:2001_categorical,fujimura:2011_categorical}. Nor are the patterns of discrimination due to narrowly visual features of the stimuli used \citep{sato:2009_detection}. We can be confident, then, that the patterns of discrimination probably reflect one or more processes which categorises stimuli by expression of emotion.
Don't have details, this is just to stress it's early (around 200ms) and plausibly automatic.

Batty & Taylor (2003, figure 2)

At least some of the processes underpinning categorical perception of facial expressions of emotion are rapid (occurring within roughly 200 milliseconds of a stimulus' appearance), pre-attentive \citep{vuilleumier:2001_emotional} and automatic in the sense that whether they occur is to a significant degree independent of subjects' tasks and motivations \citep{batty:2003_early}.%

Is it perceptual?

Maybe for fear & happiness

- ERP (Campanella et al 2002)

But are any of the processes that categorise stimuli by expression of emotion perceptual? %That is, are the observed abilities to discriminate expressions of emotion ever based on perceptual processes? Answering this question is complicated by the fact that many parts of the brain are involved \citep{adolphs:2002_recognizing,vuilleumier:2007_distributed}. There is evidence that both the amygdala \citep{harris:2012_morphing,harris:2014_dynamic} and also some cortical structures \citep{batty:2003_early} respond categorically to expressions of emotion; and that intervening in the operations of the somatosensory cortex can impair categorisation (\citealp{pitcher:2008_transcranial}; see also \citealp{banissy:2011_superior}). To my knowledge, so far it is only for happy and fearful stimuli that we have direct evidence from both neurophysiological \citep{Campanella:2002aa} and behavioural measures \citep{williams:2005_looka} of categorisation occurring in perceptual processing. So while the evidence is not conclusive, there is converging evidence that some perceptual processes categorise stimuli including faces by expression of emotion. Humans may have categorical perception not only for speech, colour, orientation and other properties but also for expressions of emotion.
What do I mean by perceptual here? Distinguish perceptual process vs. perceptual experience. I suppose that perceptual experience of emotions or their expressions requires that there are perceptual processes which carry information about them. (Note that not everyone would agree with this; many appear to think that claims about perceptual experience float free of claims about the psychology and neurophysiology of perception.)
What exactly is the evidence? (Never trust a philosopher on science.)
An ERP is an event-related potential; it is a recognisable electorophysiological signal, measured by, for instance, EEG, that is associated with a particular neurological process. For instance, there are ERPs associated with aspects of inhibitory control.
‘The higher amplitude of the N170/VPP for the second face of between pairs as compared to within and same pairs can be understood when that subjects are confronted with two faces (in between pairs) perceived as different expressions (happiness and fear) by the perceptual system.’

‘The higher amplitude of the N170/VPP for the second face of between pairs as compared to within and same pairs can be understood [... thus:]subjects are confronted with two faces (in between pairs) perceived as different expressions (happiness and fear) by the perceptual system.’

\citep[p.~219]{Campanella:2002aa}
What does the N170 have to do with the perceptual system?

‘The N170/VPP is considered as the process indexing the structural analysis of facial information in order to obtain a configurational face representation (Jeffreys, 1996)’

\citep[p.~219]{Campanella:2002aa}
N170 / VPP is a marker of face processing generally; so if you think that is perceptual, then the presence of the N170/VPP here gives you a reason to think that categorical perception of expressions of emotion is perceptual too.

Campanella et al (2002, 219)

‘visual search was more efficient when the targets displayed emotional rather than neutral expressions’

\citep[p.~46]{williams:2005_looka}

Williams et al (2005, 46)

Earlier I asked, what evidence could bear on the perceptual hypothesis? Now we have a partial answer.

‘We sometimes see aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

McNeill (2012, p. 573)

\citet[p.\ 573]{mcneill:2012_embodiment}: ‘We sometimes {see} aspects of each others’ mental lives, and thereby come to have non-inferential knowledge of them.’

challenge

Evidence? Categorical Perception!

Part of the evidence relevant to the perceptual hypothesis is evidence that humans can categorically perceive expressions of emotion.
But what does the evidence from studies of categorical perception tell us about the truth or falsity of the perceptual hypothesis ?
Just here it is natural to take a sceptical line and claim ...
Argument:

1. The objects of categorical perception, ‘expressions of emotion’, are facial expressions.

so ...

2. The things we perceive in virtue of categorical perception are not emotions.

Some have tried to resist the conclusion by arguing that expressions are parts of emotions. This raises some complex issues that I won’t delve into here, since Will McNeil has already given an excellent argument on this topic in a paper mentioned on your handout.
Can the argument be blocked by claming that expressions are parts of emotions? See \citet{mcneill:2012_embodiment}.
Instead I want to consider the first step of the argument. Is this true? Actually we haven’t considered this carefully at all. For a start, we are talking about expressions of emotion but we haven’t yet paused to consider what they are. More pressingly, we wse have to ask, What are the objects of categorical perception? That is, What Are the Perceptual Processes Supposed to Categorise?
 

Aviezer’s Puzzle about Categorical Perception

 
\section{Aviezer’s Puzzle about Categorical Perception}
 
\section{Aviezer’s Puzzle about Categorical Perception}

What are the perceptual processes supposed to categorise?

standard view: fixed expressions linked to emotional categories

Aviezer et al (2012, figure 2A3)

Are the things categorised by perceptual processes facial configurations? This view faces a problem. There is evidence that the same facial configuration can express intense joy or intense anguish depending on the posture of the body it is attached to, and, relatedly, that humans cannot accurately determine emotions from spontaneously occurring (spontaneously occurring---i.e.\ as opposed to acted out) facial configurations \citep{motley:1988_facial,aviezer:2008_angry,aviezer:2012_body}. These and other findings, while not decisive, cast doubt on the view that categories of emotion are associated with categories of facial configurations \citep{hassin:2013_inherently}.

Aviezer et al’s puzzle

Given that facial configurations are not diagnostic of emotion, why are they categorised by perceptual processes?

This evidence makes the findings we have reviewed on categorical perception puzzling. Given that the facial configurations are not diagnostic of emotion, why are they categorised by perceptual processes?% \footnote{ Compare \citet[p.\ 1228]{aviezer:2012_body}: `although the faces are inherently ambiguous, viewers experience illusory affect and erroneously report perceiving diagnostic affective valence in the face.' } This question appears unanswerable as long as we retain the assumption---for which, after all, no argument was given---that the things categorical perception is supposed to categorise are facial configurations. .handout: :t \citet[p.\ 1228]{aviezer:2012_body}: `[A]lthough the faces are inherently ambiguous, viewers experience illusory affect and erroneously report perceiving diagnostic affective valence in the face' \citet[p.\ 1228]{aviezer:2012_body}. But do they?

‘[A]lthough the faces are inherently ambiguous, viewers experience illusory affect and erroneously report perceiving diagnostic affective valence in the face'

Aviezer et al (2012, 1228)

... maybe they aren’t.

But if we reject this assumption, what is the alternative?

conclusion

Do humans every perceive others’ mental states?

To answer this question, we need evidence.

There is evidence for categorical perception of facial expressions of emotion.

Standardly, categorical perception is evidence for perception of facial expressions ...

... which are not mental states.