The focus of the debate about morphemic complex words is whether they are represented as a whole or decomposed into morphemes in the mental dictionary. A lot of research has been done on this with various methods and formed three theoretical models (Baayen, Dijkstra, & Schreuder, 1997; Butterworth, 1983; Fiorentino & Poeppel, 2007; Isel, Gunter, & Friederici, 2003; Libben, Derwing, & De Almeida, 1999; Taft & Forster, 1975). The full-listing models believe that compound words are represented as a single unit, and the decomposition model assumes that compound words are decomposed into morphemes for representation. The hybrid model integrates the two models and believes that both forms of representation exist. In recent years, many studies using EEG and MEG have found that manipulating the morpheme characteristics of compounds can affect the early electrophysiological response, which has accumulated evidence for the decomposition model (El Yagoubi et al., 2008; Fiorentino & Poeppel, 2007; Koester, Holle, & Gunter, 2009; J.X. Zhang et al., 2012). For example, the central-parietal N200 (J. X. Zhang et al., 2012). It is a more economical way to store multi-morpheme words in a decomposed form in a mental dictionary and to combine them to express new concepts when needed (Gagné & Shoben, 1997). Especially written Chinese, as a meaning spelling or pinyi systems, there is a combination operation in the formation of words. Therefore, it is not surprising that evidence supporting decomposition storage is found in studies using Chinese as materials (Zhang, 2011).
In a study by Zhang (J.X. Zhang et al., 2012), subjects were presented with a series of two-character real and pseudo words, and they were asked to distinguish between them. Depending on the relationship between prime-target word pairs, they defined four conditions: 1. The control condition, the two are completely unrelated (such as 钱币-微弱, meaning coin-weak); 2. The whole word repeated condition, the two are the same word (such as 思索-思索, meaning thinking-thinking); 3. The first character repeated conditions, the first character of the two is same but the second character is different (such as 荣幸-荣华, meaning honor-splendor); 4. The last character repeated condition, the second character of the two is the same, but the first character is different (such as 流利-互利, meaning fluency-mutual benefit). Compared with the control, the amplitude of N400 declined under the three repeated conditions (2, 3, and 4). More importantly, under all conditions, a negative wave appeared about 200 ms after the onset of the stimulus (considering its wide distribution in the frontal, middle, and parietal brain regions, we called it the central-parietal N200). Contrary to the decrease of N400 during the repeated condition, N200 will significantly increase amplitude under repetition. This enhancement effect is more significant in whole word repeat conditions than in partial repeat conditions. That is to say, when the morphological similarity between the prime and target is greatest, the magnitude of the N200 repetition effect is also the largest. When the morphological similarity between the prime and target is smaller, the N200 repetitive effect's extent is also smaller. This result provides direct evidence for N200 to reflect orthographic processing.
The character experiment also found, the repetition effect of N200 also exists on both pseudo and non-character, but the magnitude is smaller than that of real character. These two types of stimuli are also composed of radicals. They all triggered N200, just like real characters, indicating that the radicals in the three types of stimuli above mentioned can elicit N200. That is, N200 reflects the processing of the radicals, and this processing does not depend on its location. After learning and using the real characters, its components' positional relation has a pre-existing representation in the brain.
In contrast, the positional relation between radicals of the pseudo and non-character has no pre-existing representation in mind. The N200 effect of real characters is greater than that of pseudo-characters and non-characters, which suggests that this effect reflects not only the processing of radicals but also the access to the prior representation of the positional relation of radicals(Zhang, 2013).
Combining single characters to form two-character words may be similar to combining radicals to create single-characters. Both single-character and double-character words can elicit N200 responses, but the amplitude of N200 elicited by double-character words is more robust than single characters. It may be because the N200 response to a double-character word is a superposition of that of its two constituents. Du et al.'s research adopted a delayed repetition priming paradigm and included two conditions: the whole word repetition condition(经理-经理, meaning manager-manager) and the constituents repetition condition(士护-护士, the former is a pseudo word and the later means nurse). They found the N200 effect of the whole word repetition condition is more significant than that of the constituent repetition condition (Du, Hu, Fang, & Zhang, 2013). However, the morphemes contained in them are the same, which suggests that this effect may reflect the access to the pre-existing representation of the relation between morphemes in addition to the representation of themselves (Jia, 2016).
Zhang's research found that N200 may reflect the processing of visual word representation at the level of orthography. The above inference shows that N200 is also very sensitive to the relation between the components or morphemes of single or double-character words. Relations of multi-morpheme words can be divided into grammatical and semantic relations (Cui et al., 2018; Ji & Gagné, 2007). At the grammatical level, unlike the compound words in Indo-European languages, modifier-noun is the dominant structure. There are five grammatical structures in Chinese. For example, subordinate (e.g.,野鸡, meaning pheasant), which corresponding to modifier-noun structure in English; coordinative (e.g.,灯火,meaning lights); verb-object (e.g.,开学,meaning school opens); supplement (e.g.,延长,meaning extended); subject-predicate (e.g.,地震, meaning earthquake). Among them, the coordinative structure is unique. Unlike other types, there exists no dominant morpheme(the head). Its two constituents play the same role in the semantic contribution to the whole word. In languages where the subordinate is the only structure, only the effect of semantic relation could be checked. For example, Gagne discovered semantic relation priming in compound words with modifier-noun structure; that is, the target word can be facilitated by the prime word with the same semantic relation. For example, the participant would feel student vote (vote by a student) is easier to understand than student car (car of a student) if they have just watched student accusation (accusation by a student) (Gagné, 2000, 2001; Gagné & Shoben, 2002). But in Chinese, we find that both grammatical and semantic relations play an important role in compound word processing (Cui et al., 2018; Ji & Gagné, 2007; Jia, Wang, Zhang, & Zhang, 2013). Except for semantic relation priming, we also found grammatical structure priming; that is, the target can be facilitated by the prime with the same grammatical structure. For example, if the participants have just watched风雨(wind and rain, meaning storm), they will feel that风雪(wind and snow, meaning blizzard) is easier to understand than风向(meaning wind direction). And the existing research has proved that the semantic relation works in the semantic window (Jia et al., 2013). Could the structural effect reflected in the N200 period be a grammatical relation? Theoretically, the grammatical structure defines the grammatical relation between morphemes. Although it does not explain their thematic relation, the grammatical structure is the basis for establishing a semantic relation between the two morphemes (Wang, 2014). In other words, the recognition of grammatical structures must precede the more subtle semantic relations. We will design experiments below to test this hypothesis, whether grammatical combination occurs before the semantic combination.
Up to now, two studies have examined the ERP responses elicited by the grammatical structure of Chinese two-character words. Chung et al.'s study on Chinese coordinative compounds found that when the SOA is 57ms, there is a grammatical, structural effect on P250 (Chung, Tong, Liu, McBride-Chang, & Meng, 2010). Research by Gu et al. found a pure grammatical structure effect in the early stage of Chinese visual word recognition, P2a (150-180ms) may reflect this process (Gu Jiexin, Yu Liang, & Ma Pengju, 2012). But observing their ERP results, it is not difficult to find a noticeable N200 wave, and there is a significant priming effect of grammatical structure on N200. But it was ignored in both studies.
Based on the accumulated evidence above mentioned, to verify whether the grammatical structure effect occurs during the N200 period and whether this effect occurs before the semantic relation effect, we designed the following experiment. We used a sense-nonsense judgment task and a priming paradigm; EEG was recorded at the same time. We set three conditions(see Table1): 1. The prime and target sharing the same grammatical structure and the same semantic relation (condition S); for example, 仓库-朋友(warehouse-friend), they both belong to coordinative in grammatical structure and synonymous combination in semantic relation; 2. The prime and the target have the same grammatical structure but different semantic relation (condition D). For example, 日夜-朋友(day and night-friends), they all belong to coordinative in grammatical structure. But in semantic relation, the previous one belongs to antonymous combination, while the latter belongs to synonymous combination; 3. The prime and the target has no relation; that is, both the grammatical structure and semantic relation are all different between them(condition N), for example, 书店-朋友(bookstore-friend), where the prime belongs to subordinate structure, the target belongs to the coordinative structure.
Table 1. should be inserted here
Table 1
Examples of experimental materials.
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Semantic relation
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Grammatical structure
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Examples(prime-target)
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S
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same
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same
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仓库-朋友(warehouse-friend)
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D
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different
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same
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日夜-朋友(day and night-friends)
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N
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different
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different
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书店-朋友(bookstore-friend)
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Note: The prime and target sharing the same grammatical structure and the same semantic relation (condition S);The prime and the target have the same grammatical structure but different semantic relation (condition D); The prime and the target has no relation; that is, both the grammatical structure and semantic relation are all different between them(condition N).
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If N200 reflects the effect of grammatical structure, then N200 should distinguish words with different grammatical structures. We expect that the N200 amplitude of the N condition will be significantly different from the S and D conditions. The prime of the S and D conditions share the same grammatical structure with the target, whereas N's prime condition has a different grammatical structure from the target, reflecting the grammatical structure priming. Given the previous discovery that the semantic relation priming occurs on N400, compared with two compound words with different semantic relations, compounds with the same semantic relation have a more substantial priming effect between each other. We expect that the S condition's N400 amplitude will be smaller than that of the D condition, reflecting the semantic relation effect (relation priming). If the results meet our expectations, the grammatical structure effect occurs in the N200 period, and the semantic relation effect occurs in the N400 period. Then we would specifically outline the structural information's time course; that is, the grammatical combination occurs before the semantic combination.