The Role of Phonological Distance and Relative Support on the Productivity of the Dutch Simple Past Tense

Bram Vandekerckhove, Emmanuel Keuleers, & Dominiek SandraCenter for PsycholinguisticsUniversity of Antwerp

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Wilfing on the web, the new British pastime

Wilft u wel eens?

Maar liefst zeven op de tien mensen erkennen dat ze wel eens 'wilfen’

dus dan moet er gewilft worden

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How do we inflect novel forms?

• Dual-Mechanism Model- Regular inflection:

• Governed by rules that operate over abstract symbols• Fully productive• Default

- Irregular inflection:• Database of stored word forms• Limited productivity• Similarity-based analogies• Blocks the default

V

V suffix

wilf -edpast

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How do we inflect novel forms?

• Similarity-based single-mechanism models- Regular and irregular inflection:

• Analogy-based productivity

wilf => ?

will => wouldkill => killed

fill => filleddelve => delved

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Prasada & Pinker 1993• S. Prasada & S. Pinker (1993). Generalisation

of Regular and Irregular Morphological Patterns. Language and Cognitive Processes 8, 1-56.

• Past tense acceptability ratings• Rate on a scale from 1 to 7

- Today, I spling, yesterday I splinged- Today, I spling, yesterday I splung- Today, I plip, yesterday I plipped- Today, I plip, yesterday I plup

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Prasada & Pinker 1993, stimuli

• Type: distance from irregular/regular verbs• Distances: Prototypical/Intermediate/Distant• Pattern: Vowel change/suffix

Pseudo-irregular verbs Pseudo-regular verbs

Proto. Interm. Dist. Proto. Interm. Dist.

spling fring trisp plip brilth frilg

splungsplinged

frungfringed

trusptrisped

plupplipped

brulthbrilthed

frulgfrilged

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Prasada & Pinker 1993: Predictions

• Dual-Mechanism Model- Irregular inflection:

• Negative effect of Phonological Distance from existing irregular verbs

- Regular inflection:• No effect of Phonological Distance from existing regular verbs

• Analogy-based models- Regular and irregular inflection:

• According to Prasada & Pinker (1993) (!): Effect of Phonological Distance from existing regular and irregular verbs

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Prasada & Pinker 1993: results

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However ...

Is a similarity-based model really bound to fail in strong dissimilarity

conditions?

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Memory-Based Modelling

spling

spring cling

stingswing

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Memory-Based Modelling

wilf

willfill

killfill

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Prasada & Pinker 1993: back to the stimuli

Pseudo-irregular verbs Pseudo-regular verbs

Proto. Interm. Dist. Proto. Interm. Dist.

spling fring trisp plip brilth frilg

splungsplinged

frungfringed

trusptrisped

plupplipped

brulthbrilthed

frulgfrilged

irr: 5.4 irr: 3.3 irr: 0 irr:0 irr:0 irr:0

reg:6.2 reg: 4.5 reg: 2.4 reg: 7.2 reg:0 reg:0

Keuleers & Sandra (submitted). Similarity and Productivity in the English Past Tense.

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Implications

• Findings of Prasada & Pinker can be explained as the result of Relative Support effects in a k-nn model.

• The question whether Phonological Distance from existing verbs in itself has a negative effect on regular/irregular productivity is still unresolved.

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A new experiment

• Investigation of the effects of Phonological Distance and Relative Support on the productivity of regular and irregular patterns of the Dutch simple past tense.

Label N (1434) Exemplars

---də 770 (0.537) hoor-hoorde, bel-belde, ruim-ruimde

---tə 339 (0.236) gap-gapte, lok-lokte, gulp-gulpte, wik-wikte

---ə 145 (0.101) laad-laadde, schud-schudde, raad-raadde

-eː- 45 (0.031) prijs-prees, slijt-sleet, grijp-greep

-ɔ- 38 (0.026) zend-zond, zink-zonk, zing-zong, tref-trof

-oː- 32 (0.022) scheer-schoor, vlied-vlood, luik-look

-iː- 16 (0.011) help-hielp, was-wies, slaap-sliep, loop-liep

-ɑ- 14 (0.010) treed-trad, eet-at, vreet-vrat, lees-las

-uː- 7 (0.005) jaag-joeg, zweer-zwoer, vaar-voer

-ɔxt 4 (0.003) koop-kocht, dunk-docht, zoek-zocht

-ɑxt 2 (0.001) breng-bracht, denk-dacht

...

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Method

• Past tense acceptability rating task• Stimuli selected on the basis of the output of a

memory-based simulation, with model trained on monomorphemic verbs (CELEX):- Phonological Distance of the nearest neighbor- Relative Support for one of 6 past tense classes (3

regular allomorphs, 3 largest vowel-change classes)

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Predictions• Dual-Mechanism Model

- Regular inflection• No effect of Phonological Distance• Possible postive effect of Relative Support (partial

blocking)

- Irregular inflection• Negative effect of Phonological Distance• Positive effect of Relative Support

• K-nn model- Regular and irregular inflection

• Positive effect of Relative Support• No effect of Phonological Distance

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Results plot

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Results and Discussion

• Positive effect of Relative Support on mean ratings for both regular and irregular forms

• Negative effect of Phonological Distance on mean ratings for irregular forms

• No significant effect of Phonological Distance on mean ratings for regular forms

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Results and discussion

• Regular inflection- Both models make the correct predictions.- Preference for k-nn model.

• Irregular inflection- K-nn model makes the wrong prediction.- Preference for Dual-Mechanism Model?

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An alternative explanation

• K-nn model is a rather crude implementation of the memory-based approach to cognitive/linguistic modelling.

• Generalized Context Model:(Nosofsky, R. M. (1988). Similarity, frequency and category representations. Journal of Experimental Psychology: Learning, Memory and Cognition, 14, 54-65.):- k nearest neighbors = the whole lexicon- Exemplars are weighted by an exponential decay

function

An alternative explanation

k1 k7 k1 k1k7 k7

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An alternative explanation

• In the k-nn model, irregular nearest neighbors that had a relatively high Phonological Distance from the test item might have been too influential in comparison with items that were somewhat further away

• We have not yet explored this possibility.

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Conclusions

• A k-nn model is very good model of regular productivity.

• At the moment, a dual-mechanism model seems to account best for the productivity of the Dutch simple past tense.

• However, a more sophisticated implementation of the memory-based approach might be a better model for this pattern of results.