Morphology and Meaning in the English Mental Lexicon

Morphology and Meaning in the English Mental Lexicon By William Marlsen-Wilson, Lorraine Komisarjevsky Tyler, Rachelle Waksler, and Lianne Older Presented by Robyn Maler

Questions • How are lexical entries represented in the mental lexicon? • Are their representations based on whole phonetic words (full listing hypothesis) or morphemes (morphemic hypothesis)? • Are there differences between lexical representations at different levels?

Background • Lexical entry is distinct from access representation • Morphological category: the basic linguistic characteristics of the affixes (derivational vs. inflectional, prefix vs. suffix) • Semantic transparency: whether the form is synchronically compositional • Phonological transparency: whether the form has the same phonetic shape for both its affixed and unaffixed versions

Experimental Task Design • Cross-modal immediate repetition priming: subject hears a multimorphemic spoken word (prime) and immediately after sees a visual probe (target) • Subject must make a lexical-decision response to this probe • Response facilitation (priming) is measured by response latency relative to a baseline condition (subject’s response to same probe following unrelated prime)

Questions for Experiments 1-3: • Is the lexical entry for derived suffixed words in English morphologically structured? • How does the semantic and phonological transparency of stem and affix morphemes affect the representation of a derived form?

Experiment 1 • Purpose: to determine whether there is evidence for a level of morphologically structured lexical representation that abstracts away from shared surface phonetic properties

Table 1: Experiment 1

Results and Discussion • Results are consistent with hypothesis that derived suffixed forms prime their free stems because of lexical entry processes and not just surface phonetic overlap

Experiment 2 • Purpose: to determine whether the priming observed in [+Morph] conditions in Experiment 1 are simply due to semantic relationships between morphologically related pairs instead of shared morphemes in a morphologically structured mental lexicon

Results and Discussion • Priming only occurs when there is a synchronically semantically transparent relationship between derived and stem forms • Semantic links alone can produce priming, but semantic relatedness is not the only factor affecting facilitation!

Experiment 3 • Purpose #1: to study effects of morphological type and semantic transparency more rigorously • Purpose #2: to investigate a new prime-target combination (stem-derived)

Results and Discussion • confirm results of Experiment 2 • fit with prediction of shared-morpheme account of [+Sem, +Morph] priming

Experiment 4 • Purpose #1: to investigate semantic transparency for prefixing morphology • Purpose #2: investigate morphological type (whether derived-derived and derived-stem prefixed pairs exhibit priming effects)

Results and Discussion • Like the suffixed pairs, only [+Sem] prefixed pairs showed priming • Prefixed [+Sem] derived-derived pairs show strong priming effects, consistent with idea that they are not cohort competitors • Prefixed [-Sem, +Morph] forms (e.g. mistake) are represented as monomorphemic items WHEREAS prefixed [+Sem, +Morph] forms (e.g. refasten) are broken down into abstract stems and prefixes at the level of lexical entry

Experiment 5 • Purpose: to investigate stem-derived order in prefixed pairs

Results and Discussion • Condition 3 results provide more evidence that there is no facilitation when there is no synchronic semantic basis for representing a word form as morphologically complex • Results consistent with a model of lexical representation in which there are inhibitory links between suffixes but not prefixes that share the same stem

Experiment 6 • Purpose: to explore relationship between prefixed and suffixed forms

Results and Discussion • Consistent with a cohort-based model in which there are inhibitory links between competing suffixed forms but not prefixed and suffixed forms

In summary… • Semantically transparent suffixed pairs prime each other except in the case of two suffixed forms, which demonstrate a cohort-based inhibitory effect • Semantically transparent prefixed pairs always prime each other • Semantically opaque pairs do not prime each other • Thus, semantically transparent forms are decomposed at the level of lexical entry, while semantically opaque forms are represented monomorphemically

…cont’d • Phonological opacity had no effect on results • Thus, morphemes are phonologically abstract

What does it all mean? • Results suggest that there is a modality-independent and morphologically structured lexical level • The basic unit in terms of which the lexicon is organized, at least for derivational forms in English, is the developmentally-defined morpheme • The findings are (kind of) consistent with a partial decomposition view of the lexicon

Morphology and Meaning in the English Mental Lexicon