What Can One Learn from Irregular Nominal

HEBREW PLURAL INFLECTION

Hebrew Plural Inflection: A Linear Processing in a Semitic Language

Vered Vaknin2, 1 and Joseph Shimron1, 2 1

2

University of Haifa

Western Galilee College

Author's comment: The data presented in this study was collected as part of the first author's doctoral dissertation. The authors claim equal contribution to this paper.

Address for correspondence: Joseph Shimron, Department of Education, University of Haifa and Western Galilee College, Israel. Phone: 972-526-242-026. Email: [email protected]

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Abstract Research on several Indo-European languages attests to notable difficulties in inflecting irregular nouns and verbs. In these languages, however, morphological and phonological factors are intertwined in a way that obscures the source of the difficulties. Hebrew allows isolation of morphological and phonological factors in nominal inflection. Three experiments demonstrated that as in Indo-European languages, nominal inflection of irregular nouns in Hebrew is slower than that of regular nouns and involve more errors. In addition, when phonological alterations to the noun’s stem occur with the inflection, this becomes an additional source of irregularity, which also taxes the inflectional process in reaction time and error rate. The empirical results underline the power of the default automatic suffix concatenation process as the main cause of the difficulties in irregular inflection. A theoretical contribution of this study is an interpretation of the irregularity effect based on a morphological analysis that views Hebrew as having a linear rather than a non-linear morphology. The stem-suffix match is suggested as the dominant factor affecting the inflectional process, and responsible for the difficulties in irregular inflections. It is argued that the differences between inflecting regular and irregular nouns can be easily and adequately explained as resulting from a mismatch between a stem and an affix.


Native and well-versed Hebrew speakers with an ear sensitive to language and grammar are occasionally surprised to hear their fellow speakers (or even themselves) making errors in a simple plural inflection of Hebrew nouns. For example, they may hear one say *tinokim ‘babies’ (mas. pl.) instead of the acceptable form tinokot, or *levenot ‘bricks’ (fem. pl.) instead of the acceptable form levenim. Such mistakes occur not only among new immigrants to Israel or people with a limited education: many veteran Hebrew speakers, including radio announcers, often err in the pluralization of Hebrew nouns, although most hasten to correct themselves immediately. The straightforward explanation to these mistakes is that they appear in irregular plural inflections, because their plural suffixes -im for masculine nouns and –ot for feminine nouns do not agree with the gender of their noun’s stem, their singular form. For example, the irregular noun tinok ‘baby’ (mas.) is expected to have –im as the plural suffix, and the irregular levena ‘brick’ (fem.) is expected to have –ot as its plural suffix. They are irregular in that their plural inflection runs counter to this expectation, and this creates the difficulty in ongoing processing of their plural inflection. However, in a large number of studies on Hebrew morphology, the words ‘stem’ or ‘base’ as well as ‘affix’, terms used in morphological analysis of Indo-European languages, which are characterized by linear (concatenated) morphology, do not appear at all. In a recent article on reading Hebrew (Frost, 2009) the essence of Hebrew morphology is described as follows: “Most words can be decomposed into two abstract morphemes: the root and the word pattern. Roots in most cases consist of three consonants whereas word patterns can be either a sequence of vowels or a sequence consisting of both vowels and consonants,… Roots and word patterns are not appended to

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one another linearly, as in languages with concatenated morphology. Rather, the consonants of the root are intertwined with the phonemes (and, therefore, the corresponding letters) of the word pattern.” (p. 237)

By this description of Hebrew morphology, no room evidently exists for stems and affixes. A description of plural inflection accomplished by attaching the plural suffix to a stem, as proposed above, is therefore out of place. Admittedly, the root-and-pattern morphological analysis can be used to explain difficulties in language processing due to irregularity of nominal plurals. This is so because the plural suffixes in a stem-and-affixes morphology and the endings of plural patterns in the root-and-pattern morphology are identical, and thus are equally affected by the different distribution of regular vs. irregular plural forms: Aronoff (1994) tallied only 80 masculine nouns in current use that take the ending –ot instead of the regular ending –im. He also found that the number of feminine nouns that take the –im ending instead of the regular –ot ending for feminine gender is even smaller: about thirty. Clearly, a very small minority of Hebrew nouns, although many of them are quite frequent. So Hebrew speakers should be sensitive to the vast differences between the distribution of regular and irregular plural forms whether they zoom on pattern endings or affixes. They are likely to develop a kind of automatic generalization (Rueckl, 2002), which is tailored to suite the most prevalent masculine and feminine plural forms. These automatic generalizations--the default processing-are likely to pose a difficulty when applied to irregular nominal plurals, as exemplified in our opening. However, the root-and-pattern description of Hebrew morphology seems to be inadequate for different reasons, as will be shown below. This study sets out to provide an explanation for the regularity effect based on a morphological analysis that

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views Hebrew as having a linear morphology. To the extent that our effort is succeeded one may be able to claim that in dealing with on-going language processing, such as inflections, the root-and-pattern analysis can be replaced with a more simple and adequate morphological analysis, that of stem-and-affixes, similar to other morphological processing, e.g., the Indu-European languages. We start with an introduction to the Hebrew nominal system. Then we report three experiments, designed to investigate and explain the difficulties with irregular nouns. We conclude by suggesting a unified model of word recognition and word processing, where rootand-pattern and stem-and-affixes are placed in a modified model of Hebrew word recognition and morphological processing of the kind involved in plural inflection.

Plural Inflections in the Hebrew Nominal System The traditional view of Hebrew morphology as a non-concatenated (non-linear) morphology typically considers two morphemes: a root (in the Semitic sense) and a pattern (also referred to as “template”) where the root is interdigitated in between the pattern’s phonemes, as in Frost (2009) quoted above. The morphological analysis adopted in this paper for discussing plural inflection differs from that, in being wholly linear as in Indo-European languages. We start by discussing the traditional view.

a. The non-linear view of Hebrew morphology In the traditional analysis of Hebrew morphology the root of the Hebrew noun tikšoret ‘communication’ (the phoneme /š/ sounds like /sh/ in English), consists of three consonants KŠR, and the pattern of this word is tikCCoCet, where capital Cs stand for the slots open for the consonants of the root. The vowel o marks the vocalic pattern in which the root consonants are to be articulated. The three root consonants

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combined with the vocalic pattern are often accompanied by other consonants and vowels, placed at its beginning and/or end. (For an introduction to Hebrew morphology see Berman, 1978; Ravid, 1995; Schwarzwald, 2000, 2001; Shimron, 2006). Remember though that the three vowels in our example of the pattern tiCCoCet above (/i/, /o/, and /e/) do not usually appear in the written form of Hebrew words. In most written Hebrew texts the pattern appears, in English letters, as tCCCt, that is, without any vowel signs. There are two writing systems in contemporary Hebrew: one omits almost all vowel signs except for few cases where vowel letters mark three vowels (/i/, /o/ and /u/), but even these do not appear every time. Almost all texts that adult Hebrew speakers regularly read are unvoweled. The other writing system marks all vowel signs, but mostly as diacritics: points and small strokes placed usually below, but sometime above or inside, the consonant letters. Voweled texts are used only by beginning readers up to the third grade, in books of poetry, and in prayer books. For a detailed discussion of the Hebrew writing system see Shimron (1993, 2006). A substantial number of excellent studies on Hebrew morphology that adopt the traditional approach, recognizing only roots and patterns, have proven quite convincingly that in the very initial stage of Hebrew word recognition, the root and sometimes the pattern are identified, as can be inferred from the experimental paradigm of priming (see below). Most of these studies used the masked priming experimental design (e.g., Deutsch, Frost & Forster, 1998; Frost, Deutsch, & Forster. 2000; Frost, Forster & Deutsch, 1997). In this experimental design the presentation of a target word on a screen is preceded, and afterwards succeeded, by forward and backward masking respectively. The forward mask is simply a stimulus in the form of

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crosshatching (#####), used to erase the memory trace of previous orthographic processing. This mask is normally presented for 500 ms. It then disappears, and is replaced by a string of letters, sometimes a word (hereinafter referred to as the prime), which is related in some systemic manner to the target word presented next. The prime is shown very briefly (about 50 ms). The target word that immediately follows also serves as a backward mask because it terminates the processing of the prime. The appearance of the prime being so fleeting, and terminated by the presentation of the target word, allows a very limited amount of processing—mostly of the visual (orthographic) aspect. With this experimental design, some aspects of comprehensive word recognition and comprehension can rarely be brought to the surface. Such priming is believed not to be sensitive to semantic factors, which take a longer time to build up (cf. Forster, Mohan, & Hector, 2003; Boudelaa & Marslen-Wilson, 2005). Hence, the prime, it is believed, facilitates mainly orthographic, perhaps partial phonological and morphological processing. Note however that the ramifications of masked and other types of priming effect--from superficial orthographic/phonological to morphological decomposition, and deeper, to semantic transparency--is yet debated, although the length of the interval between the onset of the prime and the target is taken by all researchers to be a significant factor. The longer the interval, the deeper its effect (cf. Boudelaa & Marslen-Wilson, 2005; Rastle, Davis, Marslenwilson, and Tyler, 2000; Rastle, Davis and New, 2004; Rueckle and Aicher, 2008). In a typical study that measures sensitivity to noun roots or patterns, the task is performed under three conditions: In the related condition the decision is made when the prime and the target share the same morphological element (a pattern or a root). For example, in investigating the ability to recognize the pattern researchers may use

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the words taklit 'record' and targil 'exercise', both having the same noun pattern taCCiC. In the control condition the prime and the target will have different noun patterns, for example, targil 'exercise’ and hafta’ah 'surprise'. In the third condition, identity, the prime and the target are identical. Here the main purpose is to verify the effectiveness of the prime in an ideal setting of total overlap. A priming effect, which may indicate root or pattern availability for the word recognition process, compares the time of reading the first two conditions, which have either the same root embedded in different patterns or the same patterns in which different roots are embedded. If the target is processed faster owing to the presentation of the prime beforehand, it indicates the existence of an extrapolation of the investigated (common) element: root or pattern, and, perhaps, a morphological decomposition that results in the identification of the repeated identical element (a root or a pattern). The question is what can we generalize from this data? As we indicated above the generalizability of the masked priming design is constrained by the extremely short exposure of the prime—too short to permit the comprehensive process required for real reading except for its very initial, perceptual step. Methodologically, the nature of the Hebrew writing system poses an obstacle to psycholinguists who try to assess the mere role of roots and patterns in the Hebrew speakers’ mental lexicon and in word recognition processes. First, when presented as a written word without vowel signs, the Hebrew word or its central morpheme must appear in a way that is identical to the root. Compare katav ‘he wrote’ (vowels included) with ktv, the same word written without the vowel signs, consisting of merely the root consonants. The consequence of this situation is that the cluster of the three consonants of the root becomes orthographically very prominent, even though it does not represent a specific word or morpheme (when defined as a minimal

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sublexical unit of associated form and meaning) since this same root gives birth to several words, which are vowelized in different manners and have different meanings. To illustrate by analogy, think of the number of English words that may be formed by adding different vowels to the consonant cluster SNG. Indeed, reading Hebrew requires that in a natural context of word decoding, readers of unvoweled words must retrieve the proper vowels from their phonological store in the mental lexicon. Unfortunately, even when the words are written with their diacritics (also referred to as “points”), these marks are so small, in proportion to the letters, that in several experimental designs, particularly masked priming, vowel signs are not likely to be perceived and decoded. In other sorts of priming (e.g., repetition-priming), which allows enough time for complete word processing (Bentin & Feldman, 1990) or bimodal-priming, where words are auditorily presented (Frost, Deutsch, Gilboa, Tannenbaum, & MarslenWilson, 2000), roots are necessarily processed together with their vowels, which are either patently presented with the root or have enough time to be retrieved owing to the extended time frame of stimulus presentation. Again, it is difficult, perhaps impossible, in a laboratory study in which a random list of word is presented to tease out the naked root alone, denuded of its vocal pattern and affixes, from the word in which it is embedded. A particularly interesting finding that appears in studies of morphological decomposition in masked priming of both Hebrew and Arabic nouns (Frost et al, 1997; Boudelaa & Marslen Wilson, 2005) is that priming nouns with roots apparently facilitate nouns' recognition, but priming them with patterns most often do not. In interpreting the difference in priming effect between roots and patterns, Frost et al (1997) suggested that although roots and patterns are both abstract entities, roots have

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some core meaning that is shared by a number of words. By virtue of this, roots play a pivotal role in the semantic networks by which the Hebrew mental lexicon is organized. The roots, the authors claimed, "facilitate lexical access to a large cluster of words that are derived from them" and "they represent primarily families of words that explicitly or implicitly share features of meaning” (italics added). On the other hand, the patterns, they said, represent a "distinguished phonological form" but "may have relatively minor roles in accessing all words that are formed with them" (p. 842). A problem with this interpretation is that it does not seem to be consistent with the widely accepted wisdom that the inherent nature of the masked priming paradigm is supposed to reflect the initial, perceptual aspect of word recognition; and that, by and large, it allows no semantic processing. If so, the semantic role of roots as central nodes of semantic networks should have no effect. Alternatively, we suggest that the root letters evoke the word’s stem, a combination of the root consonants and the vowels that are co-articulated with them. Then, through the recognition of the stem, as opposed to the semantically opaque root, the word is easily recognized. This hypothesis seems practically reasonable in considering that Hebrew readers are accustomed to reading unvoweled words in a way that forces them to fill in the vowels through top-down processing. In addition, Frost (1998, 2003), as well as Berent and Perfetti (1995), Booth, Perfetti, and MacWhinney, (1999), and Lee, Rayner, and Pollatsek, (2001), argued that initial phonological decoding starts very early, within the first 50 ms of reading. If so, it seems almost inevitable that the root letters in masked priming studies trigger recognition of the word stem by automatic translation of the root graphemes to phonemes, in conjunction with supplementing a vocal pattern to the root consonant, in relying on top-down processing. Unlike the root, the stem is pronounceable and

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meaningful, and it is the stem, as a concrete and transparent morpheme, not the root alone, that facilitates word recognition Thus, once the root has merged with the proper vocal pattern, the reader faces a stem, not just the naked root. So in performing linguistic operations such as nominal plural inflections or verbal conjugation, the Hebrew speaker is able to manipulate stems and affixes, instead of roots and patterns. Indeed we suggest below that roots and (perhaps) patterns may be identified as independent (orthographic) units in the initial stage of word recognition, but immediately afterward, when the vowels complement the consonantal root, the stem and its affixes become the active morphemes in every linguistic process (For an extended discussion of this argument see Shimron, 2006, Ch. 4.) The crucial difficulty with the root-and-pattern view of Hebrew morphology as a model for decoding and encoding Hebrew words is that neither the root nor the pattern is well specified or transparent in any lexical aspect: phonology, morphology, syntax or semantics. In the absence of definite vocal cues, the three consonants of the root can be pronounced in many ways, hence carry many meanings. Critically, the meaning of the root—if we consider the root as a morpheme that represent a minimal unit of meaning—is often difficult if not impossible to define. It is not only opaque or vague, it is also uncertain. For example, the word tikšoret ‘communication’ is loosely associated with the English meanings of the words ‘knot’ kešer, ‘associated’ kašur, ‘link’ kišur, or a soldier who operates his unit's radio instruments and a midfielder in a football (soccer) team—both kašar. This same root is also embedded in the Hebrew word for ‘context’, hekšer. Considering these multiple meanings of the root, its characterization as “abstract” morpheme (cf. Frost et al., 2000b) is only justified in conveying the notion that the root has no transparent meaning. In too many cases the

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identification of a known root in an unfamiliar word is actually not helpful in deciphering the word. The situation is somewhat different with verbs, where there is high semantic affinity between inflections of the same root within a specific binyan (e.g., kashar ‘he tied’ ekshor ‘I’ll tie’), although much less affinity across binyanim. In addition, with root and pattern as the morphemes of Hebrew, a simple process like plural inflection requires that this be produced anew by the replacement of one entire pattern of a singular form with one entire pattern of a plural form--instead of being achieved by a fairly simple, fast, and productive process, based on affixation according to an automatic (rule based) default rule. Finally, many Hebrew words do not have root in any meaningful linguistic sense. These are not necessarily infrequent, novel or foreign words imported into Hebrew. Some of these words are very frequent. They have a familiar word pattern, but the three consonant letters embedded where the root consonants are expected do not satisfy any criterion by which a root is measured. According to Berman (1993), actual roots must satisfy three criteria: (a) they occur in more than a single word; (b) at least one of these words is a verb; (c) the consonantal string has an independent semantic content that is embedded in a word (a condition that is difficult to satisfy, as explained above). As an example of an actual vs. a non-actual root, compare gibor ‘hero’ with rimon ‘pomegranate’. The word pattern of these two words is identical: CiCoC. However the root of the first word (GBR) occurs in more than one word, of which at least one is in a verbal form (e.g., etgaber ‘I will prevail’). In addition, the two words gibor and etgaber have a common meaning, that of prevailing. By contrast, the three consonants of the word rimon ‘pomegranate’ (RMN) cannot be considered as a root by even one of the above criteria.

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We are not familiar with statistics about the percentage of “rootless” words in Hebrew, but their number and frequency are not at all negligible. For example, yad ‘hand’, beten ‘abdomen’ ‘af ‘nose’, rosh ‘head’, saf ‘doorstep’, delet ‘door’, xalon ‘window’, asla ‘toilet bowl’, madaf ‘shelf’, menorah ‘lamp’, kir ‘wall’, sakin ‘knife’, mazleg ‘fork’, kaf ‘tablespoon’, kapit ‘teaspoon’, kise ‘chair’, shulxan ‘table/desk’, tmuna ‘picture’, radyo ‘radio’, ca’acu’a ‘toy’, ‘ax ‘brother’, axot ‘sister’, ‘av ‘father’, ‘em ‘mother’, and so on and so forth. Importantly, rootless nouns can be inflected in exactly the same way as nouns with roots, (e.g., rimon-rimonim ‘pomegranates’ mas. pl.), and serve as a base for all kinds of derivations, e.g., ‘aba-‘abahut ‘fatherfatherhood’; however these inflections and derivations are most convincingly characterized as linear productions rather than nonlinear, as will be demonstrated in the next section. The lesson from this analysis is that roots are not absolutely essential elements of Hebrew words and may not be eligible to be considered as morphemes. Frequent words such as those mentioned in the list of rootless words above can be decoded easily, even though they have no roots. Moreover, by themselves roots cannot be manipulated in linguistic processes such as inflection or conjugation because their phonological value is not yet determined so that their status as morphemes is unclear. For further discussions of roots and non-roots see Aronoff (1976) and Berman (1978, 1993).

b. The linear view of Hebrew morphology The alternative morphological analysis of Hebrew holds the stem as the central unit of the Hebrew word. The stem is the combination of the three consonants of the root and the vocalic pattern produced by interdigitation in between the root

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consonants. For example, in the word tikšoret, again, the stem is kšor, while ti- and – et are perceived and manipulated as affixes. The combination of the root with a specific vocal pattern necessarily reduces to a minimum or nullifies all but one phonological and semantic value, thereby being made a transparent morpheme. The stem as a transparent morpheme, together with inflectional and derivational affixes, can be used in the most productive and economic manner in the formation of inflections and conjugations. The stem of the verb katav ‘he wrote’, formed by combining the root KTV with the vocal pattern -a-a-, where the dashes stand for the root consonants, can form every kind of verbal inflection in the past tense by a simple linear mechanism. For example, the past tense singular forms katav-ti ‘I wrote’, katav-ta, ‘you wrote’ and the unmarked stem katav ‘he wrote’. The advantage of stems and affixes as the basic units of Hebrew morphology is that these, contrary to the root and the pattern, are well specified and transparent, both phonologically and semantically, and therefore, they facilitate the mapping of well specified morphophonological units on relatively well specified units of meanings. The semantic side of the phonology-to-semantic mapping is more malleable due to linguistic changes along the dimensions of time and space, although it also easier to tweak by tuning to the spoken language at specific linguistic context. Simple and transparent mapping of forms on meanings is justifiably considered essential for efficient language acquisition and language use such as decoding and encoding words in listening and speech or reading and writing (Plaut & Gonnerman, 2000; Rastle & Davis, 2008). As we shall soon see, the same specificity and transparency that enable simple form-to-meaning mapping when stems and affixes are concatenated or decomposed in Indo-European languages characterize Hebrew too:

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the nominal stem katav ‘writer’ (or ‘reporter’) can be productively inflected to form the plural katavim ‘writers’ (mas. pl.). In advocating an analysis of Hebrew morphology as a linear process, consisting of stem and affixes, we do not assert that roots and patterns don't exist; the Semitic root, while not directly involved in morphological processes such as inflections and derivations, may be perceived as the remnant of a semantic kernel unit that appeared in a group of Hebrew words, analogous to the semantic radicals that appear in the traditional Chinese and old Egyptian writing systems. It also functions as a central mechanism for the formation of new words by combining roots with selected word patterns (Ornan, 2003; Ephratt, 1985). It is perhaps the case that Hebrew employs two morphological systems, one for forming new words (by roots and patterns, and another for daily (common) language processing (by stems and affixes.) The two (parallel) morphological systems are employed in different linguistic operations: Roots and patterns, is mostly used in word formation and word recognition while stems and affixes are mostly used for nominal and verbal inflections. Gafos (2003) discussed the construct of linguistic paradigms as regulating and restricting the diversity of Semitic stems as central elements within these paradigms. He argued that "grammar, as a system of lawful relations between words, must have access to more richly specified underlying representations than allowed by consonantal roots" (p. 348). Gafos offered a distinction between grammar and processing, which we would like to apply to a distinction between language forms and language use:

Phonology and morphology are components of the grammar. Lexical processing is the grammar in use. The relation between grammar and processing is complex or at least indirect (Chomsky, 1965). The information structures implicated in processing must be related to units of morphology, but

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that does not mean that they must be exactly identical to them….,Morphology may operate on units distinct from consonantal roots (p. 348).

As pointed out above, as a unit of three consonants, which always appear in the same order, the root is easily recognizable as a prominent consonantal structure and an orthographic trio in Hebrew written words. This is particularly apparent in reading the Hebrew writing system, which omits most vowel signs, thus strongly underlining the three-consonant cluster of the root and inspires its perception as a central linguistic element (see Shimron, 1993). Patterns are word structures that can be classified in mishkalim—nominal structures, and binyanim—verbal structures. There also exist structural categories of adjectives and adverbs that will not be discussed here. There are about 100 mishkalim (nominal patterns), all of them may be inflected for gender and number in similar ways, as will be discussed in some detail below. The number of verbal patterns is even higher. They are arranged in seven major categories or classes of inflections (see Aronoff, 1994). Each binyan contains about 30 different word forms (patterns) which enable the specification of person, tense, gender and number by way of inflection. The structural differences between the seven binyanim often correlate with syntactic and semantic features such as transitivity: gadal 'grow' (intransitive), gidel 'raise' (transitive); Voice: katav 'wrote' (active), nixtav 'be written' (passive); reciprocality: hitkatev 'correspond'; causativity: hixtiv 'dictate'; and reflexivity: hitlabesh 'wear – dress himself''. Both mishkalim and binyanim can have inflectional affixes for marking person, tense, gender and number, and also derivational affixes for specifying a pattern (e.g., the ti- in tikshoret as exemplified above, or the hit- in the binyan hitpa’el. (We adopt the now common distinction between derivation and inflection by which a derivation is a result of a morphological act of lexeme

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formation. Thus differences between derivations regard core semantic features. Inflections are different forms of one and the same lexeme, which specify morphosyntactic features, such as person, tense, gender and number. See Anderson, 1992, and Aronoff, 1994). Finally, the view of Hebrew as a “rich morphology” (Plaut & Gonnerman, 2000) owing to the variety of idiosyncratic meanings of the roots--the “graded systematicity among surface forms of words and their meanings” (p. 6)--is untenable according to the linear approach. As the transparency of the stem minimizes, or even nullifies, the root's opacity, there goes most of the richness. Accordingly, Hebrew is neither richer nor poorer than most Indo-European orthographies. To summarize, according to the linear view of Hebrew morphology, roots and patterns are likely to be useful (if not essential) in creating novel words by the insertion of different roots in different word patterns. As written units, they may facilitate the initial step of word recognition, but they do not seem to take part in the traffic of the daily use of Hebrew as functional morphemes. For references on the distinction between the two analyses of Hebrew morphology (and other Semitic languages), see Bat-El, 2003; Berent, Vaknin, & Marcus, 2007; Ravid, 2006; Shimron, 2003, 2006).

C. This study Focusing now on our research, according to the linear view of Hebrew morphology, which will serve us as the conceptual framework for interpreting the results, plural inflection in Hebrew is accomplished by the attachment of an affix to a stem, no differently from the plural inflectional system of most European languages (Ravid, 2006; Shimron, 2003, 2006). As stated in the opening, plural suffixes can be

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concatenated to almost any noun's stem in accordance with the noun's gender (masculine or feminine). Masculine nouns are inflected by the plural suffix –im, e.g., katav ‘reporter’ (mas. sing.) => katavim ‘reporters’ (mas. pl.); feminine nouns are inflected by concatenating the feminine plural suffix –ot: katava (n) ‘report’ (fem. sing.) => katavot ‘reports’ (fem. pl.). In general, gender in Hebrew may be recognized with the help of the suffixal ending of the word. Masculine noun forms are unmarked and generally end in a consonant: agas ‘pear’; zamar ‘singer’ or in the stressed vowel e: mixsé ‘cover’; moré ‘teacher’. Feminine nouns are marked by the final stressed vowel -a: sirá ‘boat’; yaldá ‘girl’ or by the suffixal ending t in a variety of morpho-phonological patterns: kapit ‘teaspoon’; xanut ‘store’; axot ‘sister’; rakevet ‘train’ (Berman, 1978; Glinert, 1989; Schwarzwald, 1991a; Schwartzwald, 1982; Ravid, 1995; Ravid, 2006). Still, a number of irregularities are present in Hebrew plural inflections. As indicated in the opening, the principal kind of irregular plural inflections in Hebrew is the mismatch between the grammatical gender of the noun and the grammatical gender of the plural suffix: tinok-tinokot ‘baby-babies’ (mas. noun with a fem. plural suffix). A second kind is a mismatch between the nominal form and the noun's gender in its base (singular) form, e.g., cipor ‘bird’ – a feminine noun, possessing a masculine unmarked form. A third kind of irregularity is nouns whose singular and plural forms seem to derive from different stems: isha ‘woman’, nashim ‘women’; the singular form is derived from the stem ish ‘man’, while the plural form is derived from the stem enosh ‘human’ (Ravid, 2006; Schwarzwald, 1991b; Shimron, 2006). Another kind of irregularity (or inconsistency) in the plural inflections is phonological alterations in the stem/base of the word, which occur in regular and irregular nouns in inflection, e.g., gizra ‘sector’ => gzarot ‘sectors’(regular inflection

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with phonological changes) as opposed to tikra ‘ceiling’ => tikrot ‘ceilings’ (again regular inflection, but without phonological changes). Likewise with irregular inflections: zanav ‘tail’ => znavot ‘tails’ (irregular noun with phonological changes); shana ‘year’ => shanim ‘years’ (irregular noun with no phonological changes). This absence of consistency is not driven by syntactic or semantic factors so it cannot be predicted from the context of the word (Schwarzwald, 1991b). *** Differences between regular and irregular nouns with reference to the mismatch of stems and affixes are illustrated in Table 1. ………………………. Table 1 ………………………..

Uniqueness of Irregular Forms in Hebrew As can be seen from Table 1, the main characteristic of irregular inflections in Hebrew is gender marking not in accord with the accepted marking in the language. That is, the marking of the singular and/or the plural does not suit the given noun's gender. Unlike European languages such as English, where irregular plurals are formed in a non-linear fashion, both regular and irregular forms in Hebrew are inflected linearly. An example from English is several irregular forms characterized by vowel alternations in the stem or by the formation of a new stem. In the plural inflection of the noun woman the vowel /u/ is replaced by the vowel /e/ to form the plural form women. Vowel alternation in inflection eliminates the necessity of the plural form –s, creating an irregular inflection that is characteristic of a minority of nouns in English.


Irregular verbs in English are inflected in the past tense similarly: sing – sang. By contrast, regular inflections are formed by the linear concatenation of an inflectional suffix (in accordance with the linguistic rule) while the word's stem/base is preserved in its original uninflected form: cat – cats, jump – jumped (Pinker, 1994; Plaut & Gonnerman, 2000). As a result, regular inflection in English preserves the singular form and can be decoded relatively easily by morphological decomposition, whereas irregular inflection is formed by phonological changes which alter the singular form and therefore cannot be decomposed morphologically. The fact that phonological alterations and irregularity are systematically intertwined in the English language raises the possibility that irregularity in this language is connected by rule to the phonological changes in the stem/base form. From this one can deduce a specific explanation for the differences in processing that were found between regular and irregular inflections in English (and in other European languages featuring similar characteristics) by focusing on stem change. Stemberger (1995) indeed claims that processing differences between regular and irregular forms do not necessarily indicate different mechanisms or morphological principles. He suggests that an appropriate inflection, regular or irregular, is retrieved merely associatively, where the inflected word is associated with the stem/base form. Therefore, one can conclude that as the connections between the inflected words and the stem forms are more frequent and transparent (as in the example of regular inflection), the word will be identified faster. Consequently, one can relate the processing differences between regular and irregular forms found in English to the degree of phonological transparency between the stem form and the inflected form. Since regular inflections are formed by the concatenation of the inflected form to the stem, the connection between the stem and its regular inflected form is transparent

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and the inflection is quickly recognized. By contrast, the inflection of irregular forms involves internal changes in the form of the stem, so the connection between the stem form and its inflected form is less familiar and the identification of the irregular inflection is delayed. But is it indeed the case that regularly suffixed inflections are easier to recognize and process because of the obvious morphological connection between the singular form and the inflected plural form? The unique characteristics of the nominal system in Hebrew allow us to examine this issue. For in Hebrew, with very few exceptions both regular and (importantly) irregular nouns are inflected linearly by the concatenation of the plural suffix. And, again, some of both regular and irregular noun forms also involve phonological alterations while inflected, as implied above (Ravid, 2006; Ravid & Schlesinger, 2001; Schwarzwald, 2001, 2002). The experimental study that will be presented here aims at establishing first that the difficulties of fluent Hebrew speakers in nominal pluralization, as measured in error rates and pluralization latency or recognition, are related to the phenomenon of plural irregularity. Secondly, this study will propose and examine a model of plural inflection in Hebrew in terms of the structure of the Hebrew mental lexicon as it emerges from the accumulated data. It is suggested that the proposed model, which is in accordance with linear morphology based on stems and affixes, can explain differences (if any exist) between regular and irregular inflections, and predict how Hebrew speakers retrieve lexical and morphological forms from the mental lexicon, and generate plural inflections. With regard to the mental lexicon, a central question is whether, in addition to whole-word representations of plural forms, representations also exist of sub-lexical morphemic elements such as word stems and plural suffixes, which are concatenated

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during the process of plural inflection, in accordance with the relevant linguistic inflection rules. The proposed model is clearly dual-route, modified (as will be discussed below) according to our understanding of our data. Although the purpose of this study was not to demonstrate the merits of the dual-route model as against other models (e.g., single-route connectionist models), we found the dual-route model to be generally consistent with the data we gathered. However, we believe that there may be more than one way to model the plural system (provided the model is supported by a body of relevant data and is not falsified by other data from within the context of the same language). Moreover, we do not reject all tenets of the single-route connectionist approach. For example, one of our basic hypotheses assumes parallel distributed processing (McClelland & Rumelhart, 1981; Rumelhart & McClelland, 1982). In delineating our model we insist that the two routes operate simultaneously from the initial step of the composition or decoding of inflections. Importantly, the simultaneous processing in the two routes, as shall be demonstrated below, occasionally facilitates, but also inhibits the response required in a linguistic task.

Previous studies on noun irregularity Gollan and Frost (2001) investigated one facet of language processing difficulties that are exhibited in irregular nominal forms in Hebrew among adult Hebrew readers. The researchers attempted to evaluate the influence of irregularity by asking their subjects to determine as quickly as possible the gender (masculine or feminine) of singular noun forms displayed on a computer screen. The list of stimuli included regular masculine nouns, such as tik ‘bag’, whose morphological denomination of grammatical gender is cued by the fact that the singular form is unmarked, as well as

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irregular feminine nouns, such as nefesh ‘soul’ and derex ‘way’, which are unmarked morphologically yet are feminine. The researchers found that the response time for gender determination was quicker for regular nouns—masculine and feminine nouns whose morphological forms corresponded to their gender, than it was for irregular nouns. Recall that irregular feminine nouns that were selected for Golan and Frost's study are not marked with a morphological feminine ending (suffix), which explicitly affirms them as feminine, so they appear to be masculine. The authors suggested that the responses in respect of nouns with irregular gender markings were relatively slower because retrieval of information about their gender was delayed. Similar results on gender determination by adult readers were obtained in experiments investigating the verbal system of Italian (Laudanna, De Martino & Shimron, 2004). Additional experimental evidence has been reported for irregular inflectional processing in English (Beck, 1997; Munt et al., 1999; Prasada, Pinker & Snyder, 1990; Prasada & Pinker, 1993; Ullman, 1999), in German (Penke & Krause, 2002; Sonnenstuhl, Eisenbeiss & Clahsen, 1999) and in Italian (Say & Clahsen, 2001). These studies illustrate that irregular inflectional processing involves longer response times and a higher percentage of errors than does regular inflectional processing. It can be concluded that the processing of irregular inflections is more complex. These results are supported by Munt et al. (1999), who found, using event-related brain potentials, differences in cortical activity between regular inflection and irregular inflection of the past tense of the verb in English. The event-related potentials increased significantly in the identification of irregular verbal forms, which illustrated more complex cortical activity. More akin to the focus of this study, Prasada et al. (1990) investigated regular and irregular verbal inflection in English. They examined the hypothesis that there is an

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interaction between the processing of regular and irregular past tense verbal inflections and the frequency of the verbal stems. The participants in their study were asked to inflect regular verbs (walk – walked) and irregular verbs (drive – drove) to the past tense form after they were first presented in the present tense. Stem frequency of the regular verbs proved to exert influence on processing speed, but speed of inflectional processing of irregular verbs correlated with their frequency. The researchers concluded that regular verbs are inflected automatically by way of linear concatenation of the inflectional suffix -ed to the stem form, as dictated by the word formation rules of English. Consequently, no frequency effects on processing time were observed. On the other hand, irregular verbal forms, which cannot be inflected by the regular inflections (-ed), must be stored as whole-words in the mental lexicon. When needed, the inflected form must be retrieved individually from memory, so the frequency effects of the stem influence the speed of inflectional processing. Similar results were observed with English-speaking (Prasada & Pinker, 1993; Ullman, 1999) and Italian-speaking (Say & Clahsen, 2001) respondents. Along this line of research, Hebrew-speaking participants (Berent, Pinker & Shimron, 1999; 2002) were asked to inflect pseudo-words or to rate the acceptability and naturalness of inflected pseudo-words in their language. For example, Berent et al. (1999) showed their participants a list of stimuli comprised of pseudo-words similar to regularly inflected forms and pseudo-words similar to irregularly inflected forms. The forms varied along several levels of similarity to existing words (e.g., similar, partially similar, not similar). In Hebrew, pseudo-words were generated based on existing noun forms. For example, xiton is a regular pseudo-word similar to the existing regular noun form xidon ‘quiz’ and vinon is a pseudo-word similar to the irregular form vilon ‘curtain’. The participants were asked to write the plural form of

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the pseudo-words that sounded best as a proper Hebrew word, or to rate the degree to which a given inflected pseudo-word sounded like an acceptable and natural Hebrew word. The researchers found that the degree of similarity to existing noun forms did not influence the inflectional judgment of pseudo-words that were similar to regular words: participants tended to inflect them according to the accepted pattern of inflectional suffixes –im or –ot (the linguistic rule). However, the inflection of pseudo-words that were similar to irregularly inflected nouns was influenced by the degree of similarity to existing irregular forms. For example, the sequence of letters in the form vinon, which differs only in one consonant from the existing irregular noun form vilon (mas. sing.), was in most cases inflected as vinonot (instead of vinonim), apparently because of a similarity effect to the irregular word vilon. The researchers concluded that the representation of irregular inflections is different from that of regular inflections. Irregular inflections, which differ from the accepted pattern of inflectional suffixes, are represented as whole-words in the mental lexicon. By contrast, regularly inflected nouns are formed by the concatenation of a stem with a suitable inflected suffix as an automatic default mechanism, hence are not influenced by similarity to existing words. These conclusions agree with the hypothesis that the mental lexicon of speakers of the language contains regular stems and plural suffixes. Support for differential processing in regular and irregular inflections can be found in many child-development studies on the acquisition of plural inflection in Hebrew (see a detailed review of the literature in Ravid, 2006). Some of the findings mentioned in Ravid's article are partly relevant to the present study. For example, the results obtained by Levin, Ravid, and Rappaport (2001) on the phonological irregularities in inflected word stems (see following) show that Hebrew-speaking

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toddlers tend to preserve the phonological form of the singular noun, e.g., zaken ‘old man’ (mas. sing.) when forming the feminine singular form *zakena ‘old woman’ (instead of the correct form zkena) or the masculine plural form *zakenim ‘old men’ (instead of zkenim). They tend to preserve the principle of morphological simplicity as stipulated by Slobin (1985), disregarding the accepted form in the language. Similarly, the correct choice of inflection of the nominal possessive was also found to depend on the type of stem. Stems which undergo many phonological alterations during inflection are more difficult to process linguistically. Regardless of linguistic competence, in the formation of plural nominalizations young children exhibit difficulty in choosing the plural suffix when it is unexpected and irregular, in comparison with cases where it is expected and regular. Moreover, when the inflection entails phonological alterations in the stem of the word, the chances of success in inflection are reduced, as opposed to inflection which preserves the phonological form of the stem and does not involve phonological changes. Schiff and Ravid (2005) found that stems that do not undergo change during inflection, and in particular possess regular suffixes, are the easiest to inflect under experimental conditions. In sum, the learnability of the nominal inflectional system of Hebrew is constrained by changes that occur in the stem and by the nature of the inflectional suffix, according to gender (masculine or feminine) specifications. Attainment of the acceptable inflection of irregular noun forms takes longer than attainment of the acceptable inflection of regular noun forms. The findings reported here are in line with these developmental aspects. A correlation apparently exists between noted difficulties in irregular inflection exhibited in Hebrew speakers of all ages and the fact

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that irregular morphological forms in Hebrew are acquired over a longer period of time by young children. All the findings reported above demonstrate the greater processing complexity of irregular than of regular inflectional forms. Participants' linguistic performance with irregular inflection arguably attests to different representations in the Hebrew mental lexicon of regular and irregular forms, in a way that affects their processing. Some believe that the difficulties with irregular forms derive from the degree of morphological complexity of the language (Bertram, Schreuder & Baayen, 2000) and on its guiding morphological principles (Bentin & Frost, 1994; Plaut & Gonnerman, 2000; Pinker, 1994). They claim that the morphological characteristics that distinguish languages influence the way words are identified and inflected. Different morphological structures dictate differences in linguistic processing, resting on the representational system in the mental lexicon of a given language's speakers (Frost, Forster & Deutsch, 1997; Frost, Deutsch & Forster, 2000).

The Present Study The study of the processing of irregular noun forms in skilled Hebrew readers is still in its infancy. The results of the few existing studies, reviewed above, are limited to a small group of irregular feminine noun forms that are unmarked for gender in the singular (Gollan & Frost, 2001) or to masculine nouns concatenated to a feminine plural suffix (Berent et al., 1999; 2002). This previous research does not deal with the morpho-phonological changes in plural inflection. Nor does it characterize the psychological process that operates in Hebrew speakers during regular and irregular inflection.

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In three experiments on inflectional processing of Hebrew plural forms we examined irregularity in two experimental paradigms. The first experiment investigated the processing of regular and irregular noun forms of different kinds in an online inflectional production task. It examined the hypothesis that differences exist in inflectional production between regular and irregular noun forms in Hebrew. The second experiment, employing a judgment task, explored recognition of plural inflection of regular and irregular noun forms while controlling the morphophonological changes involved in the inflection. The third experiment examined the effect of phonological changes during inflection by means of an online inflectional production task (similar to the first experiment) to examine the combined effect of regularity and phonological changes on plural inflection. Based on previous studies mentioned above, we expected to find processing differences between regular and irregular noun forms. Experiment 1 The purpose of the first experiment was to examine the processing of regular and irregular nouns in an online production task in the course of inflection. The question was the effect of plural irregularity on the speed of participants' noun plural formation and error frequency in their process of inflecting the singular form before them.

Method Participants Forty students, native speakers of Hebrew at the University of Haifa, participated in the experiment. They were paid for their participation.

Materials and Procedure


The inflection of nouns was tested by means of an online production task. Participants were presented consecutively with 102 singular nouns (vowels marked by diacritics - nekudot). They were asked to pronounce as quickly as possible the plural form of the given noun. Response times and the number of errors in inflection (i.e., the concatenation of an incorrect plural suffix) were recorded and the regular and irregular inflected forms were compared, controlling for the nouns' frequency in Hebrew. This frequency was determined prior to the experiment by asking 100 participants (other than those who participated in the current study) to rate on a 1–7 scale their familiarity with the presented word from everyday language. The words appeared in their singular form and included diacritic marks. In all the subsequent statistical analyses, noun frequency was a covariate. The list of nouns used in the experiment contained 52 regular noun forms (e.g., sus ‘horse’, susim ‘horses’) and 50 irregular forms (e.g., nemala ‘ant’; nemalim ‘ants’: vilon ‘curtain’, vilonot ‘curtains’). Half the forms were masculine and half were feminine. Average word length (measured as the number of letters) was 4.21 letters for the regular and 3.58 letters for the irregular nouns. This experiment was run using the DMDX experimental software programmed by Jonathan Forster at the University of Arizona. DMDX is a member of the DMASTR family of experimental software developed at Monash University and at the University of Arizona by K. I. Forster and J. C. Forster. Response times were measured in ms. The experiment began with a practice (warm-up) set of 12 items. Before the presentation of each stimulus, a fixation sign (+) appeared in the center of the screen for one second, after which the target word was presented. The target word disappeared immediately following the participant response. If a response was

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delayed, the stimulus disappeared after 2 seconds and was followed by a new stimulus. The order of the words presented was randomized for each participant. Participants were asked to pronounce as quickly as possible the plural form of the given target word. Responses not included during the presentation or distorted by some technical problem due to coughing or exhaling into the microphone, were not considered in the statistical analyses. Altogether, missing values accounted for 2.5% of the responses.

Results The results were analyzed for variance (MANOVA) within and between subjects, with differences in the inflection of the different word types (regular vs. irregular) measured by response time and error rates, with noun frequency as a covariant. The data yielded a significant overall difference between regular and irregular nouns as expressed by response times and error rates, F1(2, 98) = 2.78, p = 0.066; F2(2, 38) = 31.54, p < 0.0001. In subsequent analyses, significant differences were also found between regular and irregular nouns in response times alone, F1(1,101) = 5.49, p < 0.02; F2(1, 39) = 23.19, p < 0.0001. Only partially significant results were noted with regard to the number of errors, F1(1, 101) = 0.844, p = 0.36; F2(1, 39) = 50.67, p < 0.001. Irregular inflectional processing proved slower, and involved more errors, than did regular processing, as can be seen in figures 1 below. Production errors were indexed by unacceptable plural suffixation, which complicated the inflection process and increased the probability of failures. ………………………………… Figures 1 and 2 ….………………………………


Discussion In the online production task, plural inflection of irregular nouns proved slower than that of regular nouns and involved a greater number of errors. This supports the proposition that processing of irregular nouns is more complex than that of regular nouns. These findings are consistent with results obtained in other languages and raise the possibility that the processing of irregular nouns may differ from that of regular nouns. The question is what causes the delay in the inflection of irregular nouns in skilled Hebrew speakers and readers? As will be posited below, the delay in the inflection of irregular nouns may be a consequence of automatic activation of the default process of inflection in Hebrew that is useful for the plural inflection of regular nouns, but must be inhibited or rejected in the inflection of irregular nouns. The default mechanism is activated in accordance with a linguistic rule, so that a proper plural suffix is concatenated to the stem of a word according to its gender as masculine or feminine. When inflecting irregular nouns participants must produce an irregular inflection, which deviates from or opposes the rule-governed inflection. The need to reject information aroused by the automatic process may delay the inflection of irregular nouns. To illustrate, to inflect the masculine noun xalon ‘window’, a Hebrew speaker must disregard the morphological default mechanism which arouses the plural suffix -im for this (masculine) noun, and instead produce the irregular suffix –ot (xalonot 'windows') which is the typical feminine suffix. In general, it seems, this will remain true even in fluent informal speech where the speaker does not worry much about making errors. A key question is what cues the rejection of the (default) morphological information and the adoption of the accepted inflection in the language. As will be detailed below, our model suggests that two mechanisms are simultaneously

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employed in inflectional processes: one relies on information that links the to-bepluralized stem to the whole-word inflectional representation in the mental lexicon-the associative storage, whereby xalon is linked to xalonot. The other mechanism relies on morphological rule-governed process, which concatenates an appropriate plural suffix to the stem. So in the inflection of irregular nouns, Hebrew speakers must invest considerable effort to reject the automatic (default – rule-governed) inflectional pattern because of its conflict with the information derived from the associative store. This conflict-resolution process may be what cues the rejection of the automatic morphological process in irregular inflection and delays the production of the accepted inflection. When the conflict resolution process fails completely, an error in the plural inflection occurs.

Experiment 2 The second experiment had three goals. The first, to affirm the results obtained in the first experiment by means of another experimental paradigm, in which participants were asked to judge plural forms as correct (acceptable) or not. Judgment latencies and number of errors were recorded. The second was to rule out the possibility that phonological changes during plural inflection can by themselves account for the relatively slow production of irregular plural inflections. To achieve this purpose, all the stimuli in this experiment were nouns which involved no phonological alteration in the word's stem in plural inflection. With such a selection of nouns we hoped to determine whether processing differences between regular and irregular inflections in plural inflection also exist in the absence of phonological alterations. To illustrate the kind of phonological alterations that were avoided in this experiment, we note that in Hebrew the concatenation of a plural suffix may


sometimes cause vowel deletion from the stem: pakid 'clerk', pkidim 'clerks'; or the exchange of one vowel for another: erec 'land', aracot 'lands' (Schwarzwald, 2001; 2002; Ravid & Schlesinger, 2001). However, unlike in English and other similar linear-morphology languages, in Hebrew, these changes are not related to the regularity of the word, so they occur in both regularly inflected words: tamar 'date', tmarim 'dates', and irregularly inflected words: zanav 'tail', znavot 'tails'. Thus, Hebrew permits us to examine the relationship between irregularity and vowel exchange in noun inflection by using as stimuli nouns in which vowels are not exchanged in the plural inflection process. As for the third goal, because in a judgment task correct and incorrect (better defined as acceptable and unacceptable) plural inflections were presented to the participants, the study could distinguish two kinds of unacceptable plural inflections. The first comprises irregularly inflected plural nouns (e.g., *xalonim 'windows') which although unacceptable conform to the general rule of plural inflection in the language; the type of the plural suffix (-im) is in accordance with the noun's gender: xalon (mas.). In the second (e.g., *egozot 'nuts'), the form is unaccepted as a plural, and also the plural suffix type (-ot fem.) does not agree with the gender of the singular noun form egoz (mas.). Because according to our model, the rule-governed plural suffix is always aroused as part of the morphological default mechanism, participants' judgment of the appropriateness of *xalonim is expected to be especially complex and delayed since the unacceptable plural form nonetheless conforms to the linguistic rule of pluralization in Hebrew that requires a match between the gender of the singular noun form and the gender of the plural suffix. Therefore, it should be easier to reject the second example (*egozot) than the first (*xalonim).

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Method Participants were presented with regular and irregular forms of plural inflections, some in their accepted form in the language and some in their unacceptable form. The presentation of each trial was in two stages, akin to a hybrid of a priming and a lexical-decision task: the noun in its singular form was presented first and the plural forms (accepted or unacceptable) were presented next. Both presentations were long enough to allow successful word recognition. Participants were asked to decide about the acceptability of the plural forms as quickly as possible; that is, whether the target, the plural form, suited the singular item presented beforehand. Participants Forty native Hebrew speaking students from the University of Haifa who did not take part in the first experiment participated in this study. They were paid for their participation.

Materials and Procedure Examples of the items presented in the experiment appear in table 2 below. ………………………………….. Table 2 …………………………………… Participants were presented with 45 regular and 35 irregular nouns. All the nouns appeared with the vowels’ diacritic marks. In some cases the nouns in their plural forms (as targets) were presented in their accepted plural inflection, e.g., the irregular vilon –vilonot 'curtain-curtains’; in other cases they were presented in an unacceptable plural form: vilon –*vilonim (unacceptable due to irregularity). The singular noun was

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displayed prior to the presentation of the plural form. The experimental stages of this experiment are exhibited in Table 3. ……………… Table 3 ……………… Participants were asked to decide as quickly as possible whether the pluralized noun presented was acceptable or not. Response time and the number of errors were recorded, and results for regular and irregular inflections of nouns were compared. Noun frequency was determined by means of questionnaires as described in experiment 1, and was a covariate in the analysis of variance. Average length of the regular nouns was 4.37 letters; that of the irregular nouns was 3.78 letters. In the present experiment only nouns which did not involve phonological alteration of vowels were chosen. The experiment was conducted with the DMDX program (see details above); response times were measured in ms. The experiment began with a practice set of 12 items. Participants were asked to decide as quickly as possible whether the target word presented was the accepted plural inflection of the singular noun presented beforehand. The order of the words in the list was randomized for each participant.

Results This experiment examined three hypotheses. The first was that the processing of irregular nouns will be longer than the processing of regular nouns and will entail more errors. The second was that this difference will be demonstrated even though no vowel alteration occurs in the plural inflectional process with this group of nouns. Thirdly, unacceptable plural forms that are nevertheless faithful to the base-to-suffix


matching-by-gender rule will be more difficult to reject—a difference that will be expressed in both response times and number of errors. Two analyses of variance (MANOVA) were carried out to examine the processing differences in inflection: one for nouns inflected as accepted in the language, the other for nouns inflected in unacceptable form. Analysis of variance showed a significant effect of regularity on both the mean response time and the number of errors, F1(2, 32) = 3.43, p < 0.04; F2(2, 38) = 21.98, p < 0.0001. Significant differences were found between accepted regular and irregular nouns in response times, F1(1, 33) = 4.62, p < 0.039; F2(1, 39) = 23.67, p < 0.0001 and in the number of errors, F1(1, 33) = 7.08, p < 0.012; F2(1, 39) = 33.49, p < 0.0001. The processing of irregular nouns was found to be slower than the processing of regular nouns and entailed more errors. Similar results were obtained with nouns inflected unacceptably. Analysis of variance showed a significant effect of regularity in favor of regular nouns on both mean response time and number of errors, F1(2, 40) = 16.05, p < 0.0001; F2(2, 38) = 66.33, p < 0.0001. It was especially interesting to find significant differences between the responses to regular nouns with unacceptable inflection due to a mismatch between the grammatical gender of the noun and the plural suffix: egoz – *egozot ‘nut-nuts’ (instead of the accepted plural form egozim), and responses to irregular nouns with unaccepted inflection, xalon –*xalonim ‘window-windows’ (irregular) where the presented plural form is nonetheless consistent with the stem-to-suffix matching-bygender rule. Differences between mean response times, F1(1, 43) = 29.24, p < 0.001; F2(1, 39) = 33.27, p < 0.0001 and between mean number of errors, F1(1, 43) = 17.19, p