The Objects of Categorical Perception

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The Objects of Categorical Perception

phonic gesture

expression of emotion

Compare expressing an emotion by, say, smiling or frowning, with articulating a phoneme.

Variations due to coarticulation, rate of speech, dialect and many other factors mean that isolated acoustic signals are not generally diagnostic of phonemes: in different contexts, the same acoustic signal might be a consequence of the articulation of any of several phonemes.

- isolated acoustic signals not diagnostic

So here there is a parallel between speech and emotion. Much as isolated facial expressions are not diagnostic of emotions (as we saw a moment ago), isolated acoustic signals are plausibly not diagnostic of phonetic articulations.

This is why Aviezer et al’s puzzle arises.

- isolated facial expressions not diagnostic

Both have a communicative function (on expressions of emotion, see for example \citealp{blair:2003_facial,sato:2007_spontaneous}) and both are categorically perceived, but the phonetic case has been more extensively investigated.

- communicative function

- communicative function ???

cultural variation

How emotions are expressed facially varies between cultures \citep{jack:2012_facial}.

is partially explained by historical heterogeneity

‘cultural differences in expressive behavior are determined by historical heterogeneity, or the extent to which a country’s present-day population descended from migration from numerous vs few source countries over a period of 500 y[ears]’ \citep{rychlowska:2015_heterogeneity}

and perhaps driven by communicative needs

‘people from historically heterogeneous cultures [as measured by the number of countries in which ancestors of members of the present population lived in the last 500 years] produce facial expressions of emotion that are recognized more accurately than expressions produced by people from homogeneous cultures.’ \citep{wood:2016_heterogeneity}

What do I want to conclude from this? That it is plausible to think of expressions of emotion as having a communicative function in much the sense than phonic gestures have communicative functions.

phonic gesture

expression of emotion

Compare expressing an emotion by, say, smiling or frowning, with articulating a phoneme.

- isolated acoustic signals not diagnostic

- isolated facial expressions not diagnostic

- communicative function

- communicative function ???

Why then are isolated acoustic signals---which rarely even occur outside the lab---categorised by perceptual or motor processes at all? To answer this question we first need a rough idea of what it is to articulate a phoneme. Articulating a phoneme involves making coordinated movements of the lips, tongue, velum and larynx. How these should move depends in complex ways on numerous factors including phonetic context \citep{Browman:1992da,Goldstein:2003bn}. In preparing for such movements, it is plausible that the articulation of a particular phoneme is an outcome represented motorically, where this motor representation coordinates the movements and normally does so in such a way as to increase the probability that the outcome represented will occur.

- complex coordinated, goal-directed movements

This implies that the articulation of a particular phoneme, although probably not an intentional action, is a goal-directed action whose goal is the articulation of that phoneme.

(On the link between motor representation and goal-directed action, see \citealp{butterfill:2012_intention}.)

Now some hold that the things categorised in categorical perception of speech are not sounds or movements (say) but rather these outcomes---the very outcomes in terms of which speech actions are represented motorically (\citealp{Liberman:2000gr}; see also \citealp{Browman:1992da}).% \footnote{ Note that this claim does not entail commitment to other components of the motor theory of speech perception. } % On this view, categorical perception of speech is a process which takes as input the bodily and acoustic effects of speech actions and attempts to identify which outcomes the actions are directed to bringing about, that is, which phonemes the speaker is attempting to articulate. That isolated acoustic signals can engage this process and thereby trigger categorical perception is merely a side-effect, albeit one with useful methodological consequences.

- complex coordinated, goal-directed movements

We can think of expressions of emotion as goal-directed in the same sense that articulations of phonemes are. They are actions whose goal is the expression of a particular emotional episode.

This may initially strike you as implausible given that such expressions of emotion can be spontaneous, unintentional and involuntary. But note that expressing an emotion by, say, smiling or frowning, whether intentionally or not, involves making coordinated movements of multiple muscles where exactly what should move and how can depend in complex ways on contextual factors. That such an expression of emotion is a goal-directed action follows just from its involving motor expertise and being coordinated around an outcome (the goal) in virtue of that outcome being represented motorically.% \footnote{ To increase the plausibility of the conjecture under consideration, we should allow that some categorically perceived expressions of emotion are not goal-directed actions but events grounded by two or more goal-directed actions. For ease of exposition I shall ignore this complication. }

Recognising that some expressions of emotion are goal-directed actions in this sense makes it possible to explain what distinguishes a genuine expression of emotion of this sort, a smile say, from something unexpressive like the exhalation of wind which might in principle resemble the smile kinematically. Like any goal-directed actions, genuine expressions of emotion of this sort are distinguished from their kinematically similar doppelgänger in being directed to outcomes by virtue of the coordinating role of motor representations and processes.

another comparison

categorical perception of speech

categorical perception of expressions of emotion

the objects of categorical perception are not acoustic signals,

the objects of categorical perception are not facial configurations

they are actions directed to the goal of performing a particular phonic gesture

they are actions directed to the goal of expressing a particular emotion

Aviezer et al’s puzzle

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

Reply:

Facial configurations are not what perceptual processes are supposed to categorize,

instead they are supposed to categorize
actions
directed to the goal
of expressing a particular emotion.

Recall the earlier sceptical line ...

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

2. Facial configurations are not emotions.

so ...

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

I’ve rejected the letter of the first premise. But does this matter for the claim that we perceptually experience emotions?

If we are categorically perceiving an action directed to the expression of a particular emotion, then there is a (perhaps quite weak) sense in which we categorically perception puts us in touch with the emotion.

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The Objects of Categorical Perception

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