The role of category ambiguity in normal and impaired lexical processing: can you paint without the paint?

Abstract

IntroductionMany words are categorially ambiguous and can be used as a verb (to paint) or as a noun (the paint) due to the presence of unpronounced morphology or “zero morphology”. On this account, the verb “paint” is derived from the noun “paint” through the addition of a silent category-changing morpheme. Past studies have uncovered the syntactic and semantic properties of these categorially ambiguous words, but no research has been conducted on how people process them during normal or impaired lexical processing. Are these two different uses of “paint” processed in the same way? Does this morphosyntactic structure have an effect on online sentence processing?MethodsThis study presents two experiments that investigate the effect of morphosyntactic complexity in categorially ambiguous words presented in isolation (experiment 1) and in a sentential context (experiment 2). The first experiment tested the ability to process categorially unambiguous and ambiguous nouns and verbs in 30 healthy older adults and 12 individuals with aphasia, using a forced choice phrasal-completion task, in which individuals choose whether the or to is most compatible with target words.ResultsHealthy controls and individuals with fluent aphasia all showed: (1) a bias toward the base category in selection rates for the and to, where the was selected more frequently for words identified to be base nouns, and to was selected more frequently for base verbs, and (2) longer reaction times for ambiguous (over unambiguous) words. However, individuals with non-fluent agrammatic aphasia showed a base-category effect only for nouns, with chance performance for verbs. The second experiment, using an eye-tracking while reading paradigm with 56 young healthy adults, showed a reading time slowdown for derived forms (to paint) compared to their base-category counterparts (the paint) in sentence contexts.DiscussionThese findings suggest that categorially ambiguous words likely share a common root, and are related by zero-derivation, and that impaired access to the base-category (i.e., verbs like to visit) precludes associated morphological processes and therefore the retrieval of the derived-category (i.e., nouns like the visit) in non-fluent agrammatic aphasia. This study provides insights into the theory of zero morphology, and the principles that need to be accounted for in models of the lexicon.

Zero-derivation in Korean: the effect of covert structure in real-time processing

“…Dahl and Fábregas, 2018). This study leverages the previous research suggesting that readers recognize the zero morphemes as morphological units (Lukic, 2016;Krasuska and Yoshida, 2019;Lukic et al, 2023). We investigate whether the covert structurebuilding process involved in yielding zero-derived categorially ambiguous nouns and verbs observed in English can also be detected in the case of categorially ambiguous verbs in Korean.…”

“…From the processing perspective, given that structure building incurs processing costs and building a more complex structure involves greater processing costs (Gibson, 1998(Gibson, , 2000, the zeroderived form should be more difficult to process than the base form of a categorially ambiguous word due to its greater morphological complexity, as shown in Lukic et al (2023). Lukic et al (2023) conducted two experiments to investigate how morphological complexity affected processing of categorially ambiguous words in lexical access (Experiment 1) and online sentence processing (Experiment 2). In their Experiment 1 (forcedchoice phrasal-completion task), they compared the selection rates and reaction times for the categorially (un)ambiguous nouns and verbs as in (3).…”

“…In contrast, following a theory that predicts that these words involve a process of zero derivation (Song, 1988;Koo, 2021; for English, see Marchand, 1964;Myers, 1984;Lukic, 2016;Krasuska and Yoshida, 2019;Lukic et al, 2023), the processing difficulty should be associated with word-internal structure building. Thus, we expect that adjective-derived verbs (condition B) would induce greater processing difficulty than the base adjectives (condition A) due to the morphological complexity and additional step in adding a covert category-changing morpheme in real-time processing.…”

“…An alternative account proposes that these words undergo a process of zero derivation, with the form in one category ([ ADJ balgda 'bright']) being the base, and the other ([ V balgda 'become bright']) being morphologically derived from the basecategory stem by attaching a phonologically unrealized suffix (i.e., zero morpheme) (Song, 1988;Koo, 2021; for English, see Marchand, 1964;Clark and Clark, 1979;Don, 2005;Lukic, 2016;Krasuska and Yoshida, 2019;Lukic et al, 2023; also see the discussion from the perspective of distributed morphology, which explores the syntactic structure of a lexical item; Marantz, 1993, 1994;Harley and Noyer, 1999;Harley, 2011Harley, , 2014.…”

“…(2) a. word-internal structure for the base form (e. In this study, we investigate whether only the base form ([ ADJ balgda 'bright']; 2a) is represented in the lexicon and the derived form ([ V balgda 'become bright']; 2b) is achieved through the addition of covert structure that is built during online sentence comprehension (for English, see Krasuska and Yoshida, 2019;Lukic et al, 2023).…”