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Is Categorical Perception Core Knowledge?

We've seen something like this list of properties before ... Compare the notion of a core system with the notion of a module
The two definitions are different, but the differences are subtle enough that we don't want both. My recommendation: if you want a better definition of core system, adopt core system = module as a working assumption and then look to research on modularity because there's more of it.

‘core systems are

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

(Carey and Spelke 1996: 520)

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

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

How are infants’ and adults’ categorical preception of colour related?

Witzel & Gegenfurtner, 2018:

Categorical perception in adults is (mostly) unrelated to cone-opponent mechanisms.

Skelton et al, 2017:

Categorical perception in infants is (mostly) related to cone-opponent mechanisms.

‘To test the hypothesis that infant color categorization is related to the cardinal mechanisms of color vision, we plotted [...] the stimuli and infants’ novelty response in a version of the MacLeod–Boynton chromaticity diagram. In this color diagram the axes L/(L+M) and S/(L+M) represent the cardinal mechanisms of color vision that correspond to the two main retinogeniculate color pathways.’
‘Four of the pairs for which there were novelty pref- erences straddle the vertical and horizontal axes originating from the background chromaticity, Munsell N5, on which our stimuli were presented.’

Skelton et al, 2017 figure 2

‘This of course cannot account for infants’ categorical distinction between red and yellow’

one idea .... \citep[p.~489]{witzel:2018_colora}: ‘A recent study suggested that categorical responses by infants are related to the cone–opponent second-stage mechanisms (Skelton et al. 2017). This observation contrasts with the finding that color categories in adults do not systematically relate to second-stage mechanisms. It is not yet clear how exactly categorical responses by infants relate to the categories for basic color terms by adults.’
another idea ... \citep[p.~490]{witzel:2018_colora}: ‘Infants might acquire categorical information through shared attention and other kinds of interaction with their social agents (e.g., their parents) that do not depend on language. Cross-cultural commonalities and infant color categories could also have an ecological origin. For example, they could be related to statistical regularities of color distributions in the visual environment (Yendrikhovskij 2001, Steels & Belpaeme 2005), and infants might internalize these regularities early in development.’

Witzel & Gegenfurtner, 2018:

Categorical perception in adults is (mostly) unrelated to cone-opponent mechanisms.

Skelton et al, 2017:

Categorical perception in infants is (mostly) related to cone-opponent mechanisms.

How are infants’ and adults’ categorical preception of colour related?

To continue the argument ...

In adults, categorical perception of colour disappears in the face of predictable verbal interference but not non-verbal interference

(Roberson, Davies and Davidoff 2000: 985; Pilling, Wiggett, et al. 2003: 549-50; Wiggett and Davies 2008)

Let me show you how this works (roughly following Wiggett and Davies 2008)
Recall from earlier how speed and accuracy were tested using a two-alternative forced-choice task.
Now Wiggett and Davies 2008 adapted this very slightly.
They put a word on the target (or, in Experiment 2, on the test stimuli --- that had no effect, showing that the word is important for priming and categorical perception is not a matter of matching label to label).
(They are using the Stroop effect, which I won't explain here but is worth looking up.)

source: Wiggett and Davies 2008, Experiment 1B

And here are the results from Experiment 1B. The vertical axis is mean accuracy.

In adults, categorical perception of colour disappears in the face of predictable verbal interference but not non-verbal interference

\citep{Roberson:2000ge,Pilling:2003bi,Wiggett:2008xt}.

(Roberson, Davies and Davidoff 2000: 985; Pilling, Wiggett, et al. 2003: 549-50; Wiggett and Davies 2008)

Why say that impact of verbal interference plus shaping of perceptual categories by extensions of words gives an interesting sense in which we have expeirences as of red because we label perceived objects 'red'? Two points: long-term, the extentions of perceptual category is influenced by the extension of the word; short-term, covert labelling primes the perceptual category and without this priming you do not have CP (Wiggett and Davies 2008).

‘surprising it would be indeed if I have a perceptual experience as of red because I call the perceived object ‘red’’

\citep[pp.\ 324--5]{Stokes:2006fd}

(Stokes 2006: 324-5).

The extensions of colour terms vary quite radically between languages. Ongoing research concerns whether there is any kind of universal prinicple behind the pattern.

English

Roberson & Hanley 2010, Figure 1c

Berinmo

Roberson & Hanley 2010, Figure 1b

So the extensions of colour terms varies between langauges.
Why is this relevant to the relation between infant and adult categorical perception?

The extensions of colour terms vary between languages.

(E.g. Russian colour terms include ‘goluboy’ (for lighter blues) and ‘siniy’ (for darker blues).)

Because the boundaries of adults' (but not infants') perceptual categories are influenced by the extensions of their culturally variable colour terms.
For evidence that adults' perceptual colour categories are influenced by their culturally variable knowledge of colour words, see \citet{Kay:2006ly}, \citet{Roberson:2007wg}, and \citet{Winawer:2007im};

In monolingual adults, the perceptual categories match the extensions of the colour terms in their language.

Roberson and Hanley, 2007; Winawer et al, 2007

This is an amazing finding about the power of words. Learning to use words for colours influences how we categorise them in categorical perception them.
Colour words shape adults’ categorical perception \citep{Roberson:2007wg,Winawer:2007im}.
We'll see more on this later.
But, as you'd expect, infants’ and toddlers’ perceptual categories are not influenced by the extensions of colour terms.
For evidence that toddlers who know some colour words show no influence of language on categorical perception of colours, see \citet{Franklin:2005hp}.

Infants’ and toddlers’ perceptual categories are not influenced by the extensions of colour terms.

Franklin et al, 2005

Therefore:

Infants’ perceptual categories do not match adults’ perceptual categories.

How are infants’ and adults’ categorical preception of colour related?

To continue the argument ...
The adult mode of categorical perception of colour differs from the infant-and-toddler mode in at least four respects: it disappears in the face of predictable verbal interference but not non-verbal interference (Roberson, Davies and Davidoff 2000: 985; Pilling, Wiggett, et al. 2003: 549-50; Wiggett and Davies 2008), it can be affected by short-term perceptual learning (Ozgen and Davies 2002), it depends on parts of the brain other than those on which infants' categorical perception of colour depends (Franklin, Drivonikou, et al. 2008), and the boundaries of adults' perceptual categories do not match the boundaries of infant and toddler perceptual categories.

Infant vs adult differences

  • effects of specifically verbal interference (Roberson, Davies and Davidoff 2000: 985; Pilling, Wiggett, et al. 2003: 549-50; Wiggett and Davies 2008)
  • different categorical boundaries
  • short-term perceptual learning (Ozgen and Davies 2002)
  • different neural correlates (Franklin, Drivonikou, et al. 2008)

... or not?

  • adult categorical perception in right visual field (RVF) only [??]
    (Drivonikou et al. 2007; Gilbert et al 2006; Gilbert et al 2008; Zhou et al, 2010)
  • training affects RVF only [??]
There is evidence that the infant mode of categorical perception of colour continues to operate in adults, although it is often inhibited or overshadowed by the adult mode \citep{Gilbert:2006yb}.
‘Several studies found that category effects occur only or more strongly in the right visual field but not at all or less strongly in the left visual field (Drivonikou et al. 2007, Gilbert et al. 2006, Roberson et al. 2008, Zhou et al. 2010). Visual information from the right visual field is processed in the left hemisphere and language is also processed in the left hemisphere for almost all people who are right-handed (for a review, see Ocklenburg et al. 2014). The observation that the category effect is lateralized to the left hemisphere suggested that language processing is involved in those category effects. Although several studies found evidence in support of the lateralized category effect, many other studies could not reproduce the effect, even in extensive series of experiments and with carefully calibrated color stimuli (Brown et al. 2011; Suegami et al. 2014; Webster & Kay 2012; Witzel & Gegenfurtner 2011, 2015, 2016). It has been suggested that the lateralization of the category effect occurs only at early stages and disappears at later stages of visual processing, possibly due to transfer through the corpus callosum (Roberson et al. 2008, Constable & Becker 2017)’ \citep[pp.~487--8]{witzel:2018_colora}.

How are infants’ and adults’ categorical preception of colour related?

‘core systems are

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

(Carey and Spelke 1996: 520)

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

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