Lexical and morphosyntactic minimal pairs. Evidence for different processing Luca Cilibrasi, Vesna Stojanovik, Patricia Riddell, School of Psychology, University of Reading

Minimal pairs  Minimal pairs are defined as pairs of words in a particular language which differ in only one phonological element and have a different meaning (Roach, 2000)  Pen – Pan  Hat – Had  Teach – Reach

Minimal pairs in language remediation  Minimal pairs are widely used in the treatment of phonological disorders, such as Dyslexia (Brancalioni et al, 2012, Earl, 2011, Pulvermuller et al, 2001, Crosbie et al, 2005, Blache et al, 1981, Barlow & Gierut, 2002).  However, several studies report problems, i.e. no generalisation to untreated items (Sabem & Ingham, 1991, Williams, 2000).

Representations involved  We believe there is a gap in our comprehension of how minimal pairs discrimination takes place

Lexical representations  Mono VS polymorphemic real words discrimination  How are polymorphemic words stored in the lexicon?  Plays :  [Play + s]  [Plays]

Competing approaches  Inflected forms are stored in the lexicon as units (Stemberger & MacWhinney; 1986, Bertram et al, 2000)  During language acquisition, the first strategy is to store inflected forms in the lexicon as units (Tomasello, 2006; Diessel, 2012)  Irregular forms are stored in the lexicon, regular forms are derived using a rule (Pinker & Ullman, 2001)

How is this linked to minimal pairs?  In many languages, bound morphemes, which are used to mark inflection, generate minimal pairs. These sets are referred to as “morphosyntactic minimal pairs” (Law & Strange, 2010)  Mangio – mangia – mangi  Plays – played

Null hypothesis  If inflected forms are stored as units in the lexicon, discriminating lexical minimal pairs and morphosyntactic minimal pairs should not be different processes  Badge – Back  Asks – Asked  Two monosyllabic forms differing in the final phoneme

Participants  20 monolingual native speakers of English were recruited trough wall advertising in the department of Clinical Language Science, University of Reading  Graduate students, 9 males, 11 females, mean age 25.5, standard deviation, 2.03.

Stimuli  30 monosyllabic lexical minimal pairs  30 monosyllabic morphosyntactic minimal pairs  60 pairs of identical words (30 from the first condition, 30 from the second condition)  Task:  Two words appear on the screen  Participants are instructed to press white if the two words are identical, black if they are different

Method  Task programmed using E-prime  Measures of accuracy (number of items coded correctly)  Measures of Reaction Times (msec)

Results  Accuracy is at ceiling for all subjects in all conditions and therefore will not be considered further.  RTs mean are compared in the Lexical vs. morphosyntacic condition.  Only correct responses are taken.  Trimmed means (95% of the range of reaction times recorded for each individual) are used.

Results  t (19) = , p <.001  The difference is highly significant. Morphosyntactic minimal pairs take more time than lexical minimal pairs to be distinguished

Null hypothesis  If inflected forms are stored as units in the lexicon, discriminating lexical minimal pairs and morphosyntactic minimal pairs should take the same time  The null hypothesis is rejected

Discussion  This suggests that lexical and morphosyntactic minimal pairs might require two different forms of processing  This could be because morphosyntactic minimal pairs require decomposition in stem + affix in order to be analysed (Pinker & Ullman, 2001)  Our result is not consistent with the hypothesis that inflected forms are stored as units (Bertram et al, 2000)

Alternative explanations  Elements within morphosyntactic minimal pairs are semantically linked, elements within lexical minimal pairs are not.  The distinction between two elements in morphosyntactic minimal pairs is semantically subtle, even if the elements belonging to the pair are stored in the lexicon as units with the bound morpheme

Alternative explanations  Morphosyntactic minimal pairs differ always on the same phonemes /s/ - /z/ VS /d/ - /t/ while the possible distinctions in the lexical condition are more varied.  Thus, the morphosyntactic condition is more predictable so it should be easier but it is NOT

Alternative explanations  Verbs are slower than nouns  There is evidence of dissociation but is there evidence that verbs are slower?

Conclusion  We report evidence that discriminating elements in morphosyntactic minimal pairs takes longer than discriminating elements in lexical minimal pairs.  Our tentative conclusion is that morphosyntactic minimal pairs are decomposed in order to be processed syntactically, while monomorphemic words do not require this.

Future work (in progress)  Can we operate minimal pairs discrimination without appealing to the lexicon?  Odd ball paradigm  RTs + ERPs  We expect RTs to correlate with phonological short term memory  MMN not to vary in latency in the four conditions

In progress  Presented aurally:  Side VS size  Bud VS buzz  Cared VS cares  Chewed VS chews

Past work  In a previous work we showed that we can predict reading performance using accuracy and RTs in non- words minimal pairs discrimination

The general picture  Minimal pairs discrimination can take place at the sub- lexical level and this is the level we have to focus on in order to improve reading performance. However, the lexical level tends to be involved when we use real words, as is demonstrated by the fact that polymorphemic words require more time than monomorphemic words.

Acknowledgements  My supervisors and co-authors of the presentation, Vesna Stojanovik and Patricia Riddell  My monitors, Doug Saddy and Theo Marinis  The faculty of social sciences of the University of Reading for funding the project