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<Paper uid="C90-3021">
  <Title>A Computational Theory of Processing Overload and Garden-Path Effects</Title>
  <Section position="2" start_page="0" end_page="0" type="metho">
    <SectionTitle>
2 The Underlying Parse~ -~
</SectionTitle>
    <Paragraph position="0"> The parser to which the memory limitation constraints apply must construct representations in such a way so that incomplete input will be associated with structure.</Paragraph>
    <Paragraph position="1"> Furthermore, the parsing algorithm must, in principle, allow more than one structure tor an input string, so that the general constraints described in the previous section may apply to restrict the possibilities. The parsing model that I will assume is an extension of the model described in (Clark &amp; Gibson (1988)). When a word is input to this model, representations for each of its lexical entries are built and placed in the buffer, a one cell data structure that holds a set of tree structures. The parsing model contains a second data structure, the stack-set, which contains a set of stacks of buffer cells. The parser builds trees in parallel based on possible attachments made between the buffer and the top of each stack in the stack-set. The buffer and stack-set are formally defined in (3) and (4).</Paragraph>
    <Paragraph position="2"> (3) A buffer cell is a set of structures { St ,$2, ...,S, }, where each Si represents the same segment of the input string. The buffer contains one buffer cell.</Paragraph>
    <Paragraph position="3"> (4) The stack-set is a set of stacks of buffer cells, where each stack represents the same segment of the input string:</Paragraph>
    <Paragraph position="5"> where: p is the number of stacks; mi is the number of buffer ceils in stack i; and nld is the number of tree structures in the jth buffer cell of stack i.</Paragraph>
    <Paragraph position="6"> The motivation for these data structures is given by the desire for a completely unconstrained parsing algorithm upon which constraints may be placed. This algorithm should allow all possible parser operations to occur at each parse state. There are only two parser operations: attaching a node to another node and pushing a buffer cell onto a stack. In order to allow both of these operations to be performed in parallel, it is necessary to have the given data structures: the buffer and the stack-set.</Paragraph>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
2.1 Node Attachment
</SectionTitle>
      <Paragraph position="0"> I assume a hypothesis-driven node projection algorithm of the following form. In order to satisfy X Theory (Jackendoff (1977), Chomsky (1986b)), a maximal projection is constructed for each of a word's lexical entries when that word is input. For each of these structures, the lexical requirements and category of the structure causes tile local prediction to the right of further categories. These predicted structures are called hypothesized nodes or Hnodes. All other structures are called confirmed nodes or C-nodes. For example, when the noun dog is input, a confirmed noun phrase and a h~pothesized clausal phrase are among the structures built: ~ plying the methodology described here to the Projection Principle as well as the 0-Criterion. While the effects reported in the curlier paper still hold, many additional results are obtained and reported here, 5A noun phrase is projected to an H~node clausal (or predb cate) phrase since nouns may be the subjects of predicates.</Paragraph>
      <Paragraph position="1"> (5) ao \[NV\[te, IN dog \]\]1 b. \[xv,~ \[tee ~, \[te dog \]\]\] \[x~ \[X,~.~ e \]\]\] Node attachment in this framework consists of matching hypothesized nodes on top of a stack in the stack-set against nodes in the buffer. If the features of two such nodes are compatible, then an attachment t~es place, the result being the unification of the stack and buffer nodes.</Paragraph>
      <Paragraph position="2"> Since attachment always involves matching an It-node, * all obligatory arguments are projected as H-nodes.</Paragraph>
    </Section>
  </Section>
  <Section position="3" start_page="0" end_page="0" type="metho">
    <SectionTitle>
3 Dynamic Application of the 0-Criterion
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
and Projection Principle
</SectionTitle>
      <Paragraph position="0"> Following much current work in syntactic theory, I assume that the grammar consists of a set of environments where properties such as thematic role and Case may be assigned, along with a set of filters, each of which rules out representations lacking a necessary property. This approach to syntactic theory has been labeled the Principles and Parameters Approach (PPA) (Chomsky (1986a)).</Paragraph>
      <Paragraph position="1"> The particular syntactic theory that I will assume is known as Government and Binding theory (see Chomsky, (1981, 1986a, 1986b) along with the references cited in each), although the methodology of this work will apply to any syntactic theory of this form.</Paragraph>
      <Paragraph position="2"> A filter-based syntactic theory presents an obvious set of candidate.s for load-bearing structural properties: the set of local violations of all syntactic filters. That is, given a constraint-based syntactic theory, it is reasonable to assume that there is a processing load associated with the local violation of each syntactic filter. In particular, I will consider the 0-Criterion and Projection Principle  from Government and Binding Theory with respect to a theory of processing. These principles are given in (6) and (7): (6) The Projection Principle:  Lexieal requirements must be satisfied at all levels of representation. (paraphrased from Chomsky (1981) p.</Paragraph>
      <Paragraph position="3"> 29). 6</Paragraph>
    </Section>
  </Section>
  <Section position="4" start_page="0" end_page="0" type="metho">
    <SectionTitle>
(7) The 0-Criterion:
</SectionTitle>
    <Paragraph position="0"> Each argument bears one and only one 0-role (thematic role) and each 0-role is assigned to one and only one argument (Chomsky (1981) p. 36).</Paragraph>
    <Paragraph position="1"> Note that the second part of the 0-Criterion- that each 0-role be assigned- Iollows from the Projection Principle. Thus the 0-Criterion that I will assume consists only of  the first clause of (7): (8) The 0-Criterion (simplified): Each argument bears one and only one 0-role.</Paragraph>
    <Paragraph position="2"> &amp;quot;file dynamically applied 0-Criterion can be stated as the following processing property: (9) The Property of Thematic Reception (~I'R): Associate a load of x'cn PLUs of short term memory to each constituent that is in a position that can receive a thematic role in some co-existing structure, but whose 0assigner is not unambiguously identifiable in the structure in question.</Paragraph>
    <Paragraph position="3"> 6Government and Binding Theory assumes tile existcnce of a  number of levels of representation, I assume that the level most relevant to parsing is surface structure or S..slructure. Thus the Projection F'rinciple applied to S-structure dictates flint lexical requiremenks be satisfied at that level.</Paragraph>
    <Paragraph position="4"> 2 115 The dynamically applied Projection Principle gives a similar property. This property is stated in terms of thematic elements. Following early work in linguistic theory, I distinguish two kinds of categories: functional categories and thematic or content categories (see, for example, Fukui and Speas (1986) and Abney (1987) and the references cited in each). Thematic categories include nouns, verbs, adjectives and prepositions; functional categories include determiners, complementizers, and inflection markers. I hypothesiz~ that thematic elements are more visible to the parser than their functional counterparts. This assumption is made explicit in the Property of Lexical Requirement, the dynamic version of the Projec- null tion Principle: (10) The Property of Lexical Requirement (PLR):  Associate a load of xt~ PLUs of short term memory to each lexical requirement that is satisfied by a hypothesized constituent containing no thematic elements.</Paragraph>
    <Paragraph position="5"> Note that all lexical requirements minimally involve the existence of a hypothesized structure. Thus the Property of Lexical Requirement ignores those structures whose lexical requirements are satisfied by either confirmed nodes or hypothesized nodes that contain thematic elements. The PLR will penalize only those structures with unsatisfied lexical requirements, where unsatisfied requirements consist of thematic element-less hypothesized structures.</Paragraph>
    <Paragraph position="6"> When particular processing loads are associated with each of these properties, they will make a large number of empirical predictions in the theory of overload and preference. Since both the PTR and the PLR are properties dealing with the interpretation of an utterance, it is reasonable to assume as a default that the loads associated with these two properties, XTR PLUs and xt~ PLUs respectively, are the same. 7</Paragraph>
    <Paragraph position="8"> It turns out that this a~ssumption is consistent with all inequalities that are obtained in this paper.</Paragraph>
  </Section>
  <Section position="5" start_page="0" end_page="0" type="metho">
    <SectionTitle>
4 Ambiguity and the Properties of
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
Thematic Reception and Lexical
Requirement
</SectionTitle>
      <Paragraph position="0"> In order to determine what load is associated with each of the Properties of Thematic Reception and Lexical Requirement, I will first examine locally ambiguous sentences that either cause or do not cause garden-path effects. Consider sentence (12) with respect to the ~ and PLR: (12) John expected Mary to like Fred.</Paragraph>
      <Paragraph position="1"> The verb expect is ambiguous: either taking an NP complement as in the sentence John expected Mary or taking an IP complement as in (12). 8 Thus there is a local ambiguity in (12) at the point of parsing the NP Mary. 7In fact, both the 0-Criterion and the Projection Principle are generally believed to follow from a more general principle: that of Full Interpretation (Chomsky (1986a)). If this is so, then the PLR and the PTR reduce to a single property: that of local uninterpretability. However, the principle of Full Interpretation has not yet been adequately formalized. Thus I will continue to appeal only to its components.</Paragraph>
      <Paragraph position="2"> 8Following current notation in GB Theory, IP=S and CP=S' (Chomsky (1986b)).</Paragraph>
      <Paragraph position="3"> Despite this local ambiguity, there is no difficulty parsing (12). Consider the state of the parse of (12) after the word Mary has been processed: (13) a. \[m\[Ne John \] \[re expected Lvp Mary \]\]\] b. \[m Lvp John \] \[vp expected \[m \[UP Mary \] \]\]\] In (13a) the NP Mary is attached as the NP complement of expected. In this representation there is no load associated with either of the Properties of Thematic Reception or Lexical Requirement since all constituents that are positions to receive thematic roles, do so, and all lexical requirements are satisfied. In (13b) the NP Mary is the specifier of a hypothesized IP node which is attached as the complement of the other reading of expected. This representation is associated with at least xvn PLUs (= xlnt PLUs) since the NP Mary is in a position that can be associated with a thematic role (the subject position), but does not yet receive one in this structure. No load is associated with the Property of Lexical Requirement, however, since the lexical requirements of the verb expected are satisfied by nodes that contain thematic elements. Since there is no difficulty in processing sentence (12), the load difference between these two structures cannot be greater than P PLUs, the preference factor assumed in inequality (2).</Paragraph>
      <Paragraph position="4"> Thus the inequality in (14) is obtained: (14)Xlnt &lt; P Since the load difference between the two structures is not sufficient to cause a strong preference, both structures are maintained. Note that this is a crucial difference between the theory presented here and the theory presented in Frazier &amp; Fodor (1978), Fr~ier (1979) and Pritchett (1988). In each of these theories, only one representation can be maintained, so that either (13a) or (13b) would be preferred at this point. In order to account for the lack of difficulty in parsing (12), Pritchett assumes that back-tracking in certain situations is not expensive. No such stipulation is necessary in the framework given here.</Paragraph>
      <Paragraph position="5"> Now consider a second locally ambiguous .,;entence, one that results in a garden-path effect: 9 (15) # i put the candy on the table in my mouth.</Paragraph>
      <Paragraph position="6"> Sentence (15) is locally ambiguous at the point of parsing the word on. This preposition may attach as either an argument of the verb put, or as a modifier of the noun table. The argument attachment is locally preferred, although it turns out that this attachment is not compatible with the rest of the sentence. Thus a garden-path effect results. In order to see how the Properties of Thematic Reception and Lexical Requirement can account for this garden-path effect, consider the state of the parse after the  word on has been input: (16) a. \[m \[up I \] \[vP Iv, \[v put \] \[NP the candy \] \[ee on be 1\] \]\]1 b. \[m Jut, I \] \[vt, \[v, Iv put \] Ira, the candy b,e on \[up 1\]\] \]1\]  The load associated with structure (16a) is xt~ PLUs since, although the lexical requirements of the verb put are satisfied, the lexical requirements of the preposition on remain unsatisfied. On the other hand, the load associated with the modifier attachment is 2xt~ + XTR PLUs since 1) both the verb put and the preposition on have unsatisfied 9I will prefix sentences that are difficult to parse because of memory limitations with the symbol &amp;quot;#&amp;quot;. Hence sentences that are unacceptable due to processing overload will be prefixed with &amp;quot;#&amp;quot;, as will be garden-path sentences.</Paragraph>
      <Paragraph position="7"> 116 3 lexical requirements and 2) the PP headed by on receives a thematic role in the argument attachment structure, while it receives no such role in the current structure. Ttlus the diffcrencc between the loads associated with the two structures is XLR + xrn PLUs = 2xt, t PLUs. Since the argument attachment structure is strongly preferred over the other structure, 1 hypothesize that this load is greater</Paragraph>
      <Paragraph position="9"> Now consider the well-known garden-path sentence in  (18) (Bever (1970)): (18) # The horse raced past the barn fell.  The structure for the input the horse raced is ~unbiguous between at least the two structures in (19): (19) a. be \[~p the horse \] \[vP raced \]l b. \[m ~e the IN, \[IV, horse/\] \[cp Oi raced \] \]\] \] Structure (19a) has no load associated with it due to either the PLR or the PTR. Crucially note that the verb raced has an intransitive reading so that no load is required via the Property of Lexical Requirement. On the other hand, structure (19b) requircs a load of 2XT.~ PLUs since 1) the noun phrase the horse is in a position that can receive a thematic role, but currently does not and 2) the operator O~ is in a position that may be associated with a thematte role, but is not yet associated with one. tdeg Thus file difference between the processing loads associated with structures (19a) and (19b) is 2x~ PLUs = 2xl~t PLUs. By the inequality in (17), this difference is sufficient to cause the preference of the less expensive structure. Hence the garden-path effect in (18) is predicted.</Paragraph>
      <Paragraph position="10"> Consider (20), a sentence whose structure and local ambiguities are very similar to those in (18): (20) The bird found in the room was dead.</Paragraph>
      <Paragraph position="11"> Although the structures and local ambiguities in (20) and (18) are similar, (18) causes a garden-path effect while, surprisingly, (20) does not. To determine why (20) is not a garden-path sentence we need to cxamine the local ambiguity when the word found is read: (21) a. \[)e \[UP tile bird \] \[vp Iv, \[v found IN? \] \]\]\]\] b. \[0, \[NV tile \[~v' Dr, bird/\] \[cp Oi found \] \]\] \] The crucial difference between the verb found and the verb raced is that found obligatorily requires a noun phrase object, while raced does not. Since the lexical requirements of the verb found are not yet satisfied in structure (21a), this representation is associated with xt~ PLUs of mcmory load. Like structure (19b), structure (21b) requires 2x~8 PLUs. Thus the difference between the processing loads of structures (21a) and (21b) is 2x,rtC/ - x~ PLUs = xtm PLUs. By the result obtained from sentence (12), this load difference is not sufficient to force a strong preference. &amp;quot;Ilms the lack of garden-path effect in (20) is explained. Furthermore, these results correctly predict that sentence (22) is not a garden-path sentence either: (22) Tile bird found in the room enough debris to build a nest.</Paragraph>
      <Paragraph position="12"> Consider now (23): (23) # I believe that John smokes annoys Mary.</Paragraph>
      <Paragraph position="13"> 1degIn fact, this operator will be associated with a thematic role as soon as a gap-positing algorithm links it with the object of the passive participle raced. However, when the attachment is initially made, no such link yet exists: the operator will initially be unassociated with a thematic role.</Paragraph>
      <Paragraph position="14"> When the complementiz~eC/ that is input~ it c~n~ attach as either the argument of the verb believe or as subject of believe's complement clause. &amp;quot;File argument attachment is strongly prefen'ed and a garden-path effect results in (23), since it is the other reading that is necessary for a successful parse. Consider the slate of the parse ,after the word that has been input: (24) a. \[re Me 1 \] \[vP believe \[ce \[c, \[c that lie \] \]\] \]\]\] b. Ire Eve I \] \[v? believe \[ce \[c, \[c e \] \[m \[cP that \[m \]\]\] 1\] \]\] Consider first structure (24a). All positions that can receive thematic roles, do so. Thus there is no load associated with (24a) with respect to the Property of Thematic Reception. However tile complementizer that requires an IP complement, so that x~ PLUs are associated with (24a). Consider now (24b). First of all, the CP headed by that is in thematic role receiving position, but it does not yet receive a thematic role. Thus (24b) is associated with at least xT~ PLUs. Furthermore, both the lexical complementizer that and the argument non-lexical complementizer of believe have lexical requirements that must be satisfied, but as yet are unsatisfied. Thus structure (24b) is associated with an additional 2xt~ PLUs via the Property of Lexical Requirement. Thus the total load associated with structure (24b) is xrR + 2x~ PLUs. Hence the difference between the loads of the structures in (24) is x~qC/ + x~ PLUs = 2Xln t PLUs. As we have seen ear-.</Paragraph>
      <Paragraph position="15"> lier, this load difference is sufficient for a preference to occur. Thus the garden-path effect in (23) is predicted, as desired.</Paragraph>
      <Paragraph position="16"> See Gibson (1990) for explanations of further garden-path effects inside a similar framework.</Paragraph>
      <Paragraph position="17">  5 Processing Overload and the Properties of Thematic Reception and Lexical</Paragraph>
    </Section>
    <Section position="2" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
Requirement
</SectionTitle>
      <Paragraph position="0"> The Properties of Thematic Reception and Lexical Requirement also give a plausible account of unacceptability due to processing overload. Recall that I assmne that a sentence is unacceptable because of short term memory overload if the combination of memory associated with properties of the structures built at some stage of the parse of the sentence is greater than the allowable processing  Consider one structure that results from parsing either of the sentences in (25) after the second complemeutizer that has been input: (26) Ire Lye tile Lv, \[N' mani \] \[cP \[Ne Oi \] that \[m \[m, the IN' ~' womanj \] Ice \[Ne Oj \] that \[m \]\] \]\]\]\] \]\]\] First consider (26) with respect to the Property of Thee matic Reception. There are two lexical noun phrases in (26) that need thematic roles but lack them. Furthermore, there are two non-lexical NPs, operators, that are in positions that may prospectively be linked to thematic roles. Thus the load associated with (26) is at least 4x~R PLUS.</Paragraph>
      <Paragraph position="1"> Now consider (26) with respect to the Property of Lexical Requirement. Only the two complementizers have lexic~d 4 I17 requirements in (26), and only the most recent of these is unsatisfied, since the lexical requirements of the first are satisfied by a hypothesized node with thematic content.</Paragraph>
      <Paragraph position="2"> Thus the total load associated with (26) is 4xrR +xt~ PLUS = 5xtnt PLUs. I hypothesize that this load is too much for the limited capacity of working memory: Indeed, when noun phrases with two levels of center-embedded relative clauses appear post-verbally, the resuits are still unacceptable, although perhaps better: (27) a. ?# I saw the man that the woman that won the race likes.</Paragraph>
      <Paragraph position="3"> b. # I saw the man that the woman that the dog bit likes.</Paragraph>
      <Paragraph position="4"> Since the NP the man receives a thematic role as soon as it is parsed, it does not contribute to the processing load in either of the sentences in (27). However, other factors in determining the maximal processing load of the sentences in (27) remain the same. Thus the maximal load in each of (27a) and (27b) is 4xt~t PLUs. Since each of these sentences is unacceptable, I hypothesize that this load is more than can be handled by the short term memory capacity: (28) 4xlnt &gt; K Note that sentences with only one relative clause modifying a subject NP are acceptable, as is exemplified in (29) (29) The man that Mary likes eats fish.</Paragraph>
      <Paragraph position="5"> Since (29) is acceptable, its load is below the maximum at all stages of its processing. Under the assumptions presented in this paper, the processing load associated with (29) will be greatest when the complementizer that is input. At this pointin the parse, there will be one lexical NP, the man, and one non-lexical NP, an operator, that require thematic roles but currently lack them. Furthermore, the complementizer that requires a complement IP which is not yet present. Thus the total load associated with (29) at the point of parsing that is 3xtnt PLUs. 11 Since there is no difficulty in parsing (29), we arrive at the inequality in (30): (30) 3xt~t &lt; K Thus I assume that the maximum processing load that people can handle lies above 3xtnt PLUs but below 4xt~t PLUs. Further data support this conclusion. Forexample, consider the contrast between the sentences in (3 lb): (31) a. That John smokes annoys me.</Paragraph>
      <Paragraph position="6"> b. # That for John to smoke would annoy me is obvious.</Paragraph>
      <Paragraph position="7"> Although it is possible for a clause to be subject of a matrix clause, as in (31a), an unacceptable sentence results when the subject clause contains a further clause as its subject, as in (3 Ib). The acceptability of (3 la) together with the unacceptability of (3 lb) can be easily explained in the framework offered here. Consider first sentence (31a). The maximal processing load associated with the parse of (31a) occurs as the words that and John are processed. In both of these states the load is 2xt~t PLUs, less than the available memory capacity. Thus there is no ~In fact, the load remains at 3x~ PLUs when the NP Mary is input: the NP Mary requires a thematic role, thus adding to the processing load, but the lexical requirements of the complementizer that also become satisfied at this point, since a thematic element, Mary, is now present in the hypothesized IP complement.</Paragraph>
      <Paragraph position="8"> difficulty in the processing of (31a). Consider, however, the state of the parse of (31b) after the complementizer for has been input: (32) \[tp \[ce that \[tp \[ce for \[m \]\] \]\] \] There are two complementizer phrases, both in thematic positions, which currently lack thematic roles. Furthermore, both complementizers have lexical requirements that are currently unsatisfied: that is, the complement of each complementizer neither contains a thematic element nor is a confirmed node. Thus the total load associated with (32) is 4Xlnt PLUs, which is enough ~o force processing overload. Thus the unacceptability of (32) is explained.</Paragraph>
      <Paragraph position="9"> Furthermore, the acceptability of (33) comes as no surprise to the account presented here: (33) I believe that for John to smoke would annoy me.</Paragraph>
      <Paragraph position="10"> In contrast to (31b), the first complementizer in (33) receives a thematic role as soon as it is processed. Thus the maximal processing load associated with the parse of (33) is only 3xtnt PLUs, not enough to overload short term memory.</Paragraph>
    </Section>
    <Section position="3" start_page="0" end_page="0" type="sub_section">
      <SectionTitle>
5.1 Processing Overload: Cross-Linguistic
Predictions
</SectionTitle>
      <Paragraph position="0"> The examples discussed thus far are all English ones. A strong test of the theory presented here is presented by data from other languages. First let us consider centerembeddexl relative clauses in languages closely related to English. In particular, consider Dutch and German. It turns out that multiply center-embedded relative clauses become difficult in these languages at the stone point as they do in English: on the second embedding. For example, the German sentence (34) is unacceptable, as expected: null (34) # Der Mann den die Frau die der Hund bib sah schwam.</Paragraph>
      <Paragraph position="1"> &amp;quot;The man that the woman that the dog bit saw swam.&amp;quot; Unlike English, however, German and Dutch are verb final in subordinate clauses, so that verbs with lexical requirements for three thematic elements pose an interesting test to the theory. If the theory presented here is correct and it generalizes cross-linguistically, then constructions with three initial 0-role-requiring constituents should be acceptable. It turns out that this is in fact the case, as the German example (35) illustrates: (35) Ich glaube, dab John Mary das Geschenk gegeben hat.</Paragraph>
      <Paragraph position="2"> I believe that John Mary the present given has &amp;quot;I believe that John has given Mary the present.&amp;quot; After the word Geschenk, there are three noun phrases that require thematic roles, but currently lack them. All lexical requirements are satisfied at this point in the parse, so the total load associated with this parse state is 3x~t PLUs. Thus (35) is predicted to acceptable, as desired.</Paragraph>
      <Paragraph position="3"> Another good test for the theory presented here comes from cross-serial dependencies in Dutch. 12 In examples of cross-serial dependency, noun phrase arguments appear at the beginning of a subordinate clause, followed by their thematic role assigning verbs. It turns out that 12See Bresnan et al (1982) for a discussion of the syntax of such constructions.</Paragraph>
      <Paragraph position="4"> 118 5 constructions with three initial noun phrases are perfex;tly acceptable, as is exemplified in (36): (36) ... (hat Jan Piet de kinderen zag helpen zwemmen.</Paragraph>
      <Paragraph position="5"> ... that Jan Pier the children saw help swim &amp;quot;... tlutt Jan saw Piet help the children swim?' However, these constructions lose their acceptability with rite addition of further NP arguments: (37) a..9# ... dat Jan Piet Marie de kinderen zag helpen laten zwemmen.</Paragraph>
      <Paragraph position="6"> ... that Jan Piet Marie the children saw help make swim &amp;quot;... that Jan saw Piet help Made make the children swim.&amp;quot; b. # ... dat Jan Piet Marie Karel de kinderen zag helpen laten leren zwemmen.</Paragraph>
      <Paragraph position="7"> ... that Jan Pier Marie the children saw help make teach swim &amp;quot;... that Jan saw Piet help Marie make Karel teach the children to swim.&amp;quot; This result is predicted in the fraruework presented here. Four NP arguments locally lacking thematic roles force a load of 4xtnt, too much for human short term memory capacity.</Paragraph>
      <Paragraph position="8"> Evidence from the processing of Japanese also supports the memory capacity results obtained here. Japanese is a verb final language, so that subjects and objects appear before the verb. Verbs that lake clausal complements provide an interesting test case for the theory presented here, since it is grammatical to place all NP arguments before the thematic role assigning verbs. For example, consider (38): (38) Jon wa Fred ga Biru we sukida to omotteiru.</Paragraph>
      <Paragraph position="9"> John TOPIC Fred NOM Bill ACe likes COMP thinks &amp;quot;John thinks tlmt Fred likes Bill&amp;quot; Sentence (38) is perfectly acceptable, as is predicted by the theory presented here. The processing load associated with (38) peaks at the point that the NP Biru is input: at this point there are three NP arguments which require thematic roles but currently lack them. As a result, the processing load associated with this processing state is 3xtnt PLUs, not enough to cause overload. However, when more than three NP arguments appear sentence initially, acceptability is lost, as predicted by the processing overload results obtained here: (39) a. ?# Jon wa Mary ga Fred ga Biru we sukida to sinjiteiru to omotteiru.</Paragraph>
    </Section>
  </Section>
class="xml-element"></Paper>