Models of morphological processing

As morphemes and words inevitably involve sound, structure, and meaning, morphologi- cal theories vary on the status of the morpheme and the connection between morphology and other subfields of linguistics, namely phonology, syntax, and semantics. While the DM framework, which has been adopted in this dissertation, views morphemes as syntac- tic objects, maximizing the interface transparency between morphology and syntax, other morphological theories may adopt the lexicalist view of grammar, which views the lexicon as being independent from syntax, (see a review in Carstairs-McCarthy, 1992.) or deny the existence of morphemes to begin with (e.g., the amorphous theory (Anderson, 1992)). In parallel, psycholinguistic models of morphological processing are based on their different hypotheses on at least three aspects (Milin and Feldman, 2018; Goodwin Davies, 2018):

1. Morphological rules and representation The first question that divides models of morphological processing into two main groups is on whether explicit morphological rules and representations are assumed in the models. While morphemes have their status and representation in the lexical knowledge in the combinatorial lexicon-based approach, the learning-based approach does not assume explicit rules and representations of morphemes. The combinatorial approach assumes rules for composing morphological units into complex words. Stems in this approach contain their core meaning and can further combine with other units to create new words. The learning-based approach, instead, focuses on the level of learnability and processing costs from the mapping between form and function/meaning. For instance, the Naive Discrimination Reader model (Baayen et al., 2011) views the level of difficulty in learning the relations of words or units as dependent on how distinct or dis- criminable they are from the relevant units. This model assumes no constant core meaning of lexical entries. In this view, forms such as watch, watched, watching, or watcher are not

related based on their root or core representation but only by their similarity in the con- texts they occur in. Some learning-based models (e.g., Seidenberg and Gonnerman, 2000; Gonnerman et al., 2007), however, still assumes that morphological units are involved in the form-meaning mapping (Marantz, 2013).

2. Morphological decomposition and storage The next question to which mod- els of lexical processing differ in their answer is on how morphologically complex words are processed or retrieved. The two extreme ends involve single mechanism of either full listing or full decomposition. Full listing models (e.g., Butterworth, 1983; Seidenberg and Gonnerman, 2000) proposes that all words are listed as a whole-word unit in memory. Full decomposition models (e.g., Marslen-Wilson et al., 1994; Taft, 2004; Stockall, 2004), on the other hand, maintain that complex words undergo morphological decomposition, meaning that they are always derived by grammar and not stored as a complex unit in memory (Embick, 2015). Other hybrid dual-mechanism models hold that word recognition involves both full-listing and decomposition routes. Dual-mechanism models vary on factors determining which route to be taken. One variety (e.g., Marslen-Wilson and Tyler, 1998; Pinker and Ullman, 2002) posits that ‘regular’ complex words that are formed by rules, e.g., worked, played, are decomposed, while other ‘irregular’ forms, e.g., ran, spoke, are listed as a whole unit. Other varieties of dual-mechanism model concerns factors, such as frequency or familiarity (e.g., Baayen et al., 1997; Burani and Caramazza, 1984; Caramazza et al., 1988).

3. Phonological and semantic contribution to morphological decomposi- tion Another related major question is whether there is Independent Morphological Processing (henceforth, IMP; Bacovcin et al. 2017), allowing morphological processing to happen independently of phonological or semantic overlaps. This issue stems from the methodological confound of morphological priming that morphologically related words (e.g., played -play, marker -mark) are highly likely have phonological (or orthographic) and se- mantic overlaps with each other (Marslen-Wilson, 2007). Such overlaps in form or meaning are referred to the literature as phonological and semantic transparency, respectively. To

tackle this issue of whether morphological processing can be reduced to merely the semantic and phonological transparency between the complex words and their Roots, the literature often compares between at least two of the five main experimental conditions. The first con- dition is when the primes are morphologically related and semantically transparent (henceforth, MS) to the target, for instance, prime: departure - target: depart. The sec- ond condition, in contrast, involves primes that are merely morphologically related but semantically opaque (henceforth, M) with the target, for instance, department -depart. The third condition includes primes that are not etymologically morphologically related but appear to be morphologically related to the target, i.e., the pseudo-derived condition (henceforth, pseudo-M), for instance, pigment -pig. This pseudo-M condition is not al- ways explicitly separated from the M condition in some studies but these two conditions are treated as being inherently different in this dissertation. The above conditions are only sufficient to answer the question about the role of semantic transparency on decomposition. However, it still has not dealt with potential phonological confound. The fourth condition deals with this question by including primes that are merely phonologically related (henceforth, Ph) to the targets, for instance, figment -pig. It is worth noting that in visual priming studies, it is the orthographic overlap that they investigated. The last condition is a simple semantic priming condition with primes that are merely semantically related (henceforth, S) to the target, for example, garbage-trash.

The same questions above are not restricted to affixed words but also extend to the processing of compound words.1 Compounding is considered to be a more primitive word formation process than affixation in the history of human language (Dressler, 2006; Jack- endoff, 2002). Since compounds are formed by combining existing lexical items, novel compounds can be instantly understood without any prior encounter. Such a fundamental characteristic of compounds is the reason why they should be easily segmentable so their

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In the literature on compound processing, compound words are more finely classified into the following four groups based on the position of their transparent constituents, including transparent-transparent (TT; e.g., carwash, flagpole), opaque-transparent (OT; e.g., strawberry, dashboard), transparent-opaque (TO; e.g., doughnut, staircase), and opaque-opaque (OO; e.g., hogwash, windfall). (see for instance, El-Bialy et al., 2013; Libben, 2006; inter alia). Such distinctions are beyond the scope this dissertation.

meaning can be interpreted based on their constituent words. At the same time, certain compounds have idiosyncratic meanings that are hardly interpretable through the combi- nation of meanings of their constituents. Thus, it should also be possible for compounds to be stored as a whole unit with their idiosyncratic meanings (Libben, 2006). Models on compound processing are in parallel with those on affixed word processing. Full listing models (e.g., Schreuder and Baayen, 1997) posited that compound words, e.g., breakfast, stopwatch, hometown, are mentally represented as a whole unit. The hybrid dual-route models (e.g., Sandra, 1990), on the other hand, propose that only the semantically opaque compounds, e.g., deadline, fleabag, are represented as a whole, while the semantically trans- parent ones, e.g., bedroom, birthday, are morphologically decomposed. Full decomposition models argue that compounds are processed after the decomposition into their constituents, e.g., break-fast, stop-watch, home-town. According to these models, only these constituents are mentally represented before being combined back into the compound. Researchers have attempted to account for semantic transparency within the full decomposition model, argu- ing that they do not affect the decomposability of compounds, but rather create a semantic incongruity between the meaning of whole compounds (e.g., strawberry) and the meaning obtained from their constituents (e.g., straw + berry). The inappropriate meaning acivation is then inhibited, resulting in the lack of priming effects by semantically opaque compounds in some studies (Libben and de Almeida, 2002; Libben et al., 2004; Libben, 2006).