In this paper, we focus on one example of linguistic computation at the interface between syntax (linguistic computation) and “semantics-pragmatics,” i.e., anaphora. We assume “anaphora” defined generally as in 1. We assume “semantics-pragmatics” to refer generally to the creation of meaning through language. We are concerned with “thought” as it “provides for the contents of what we say: thought as manifested in the semantics of human language” (Hinzen, 2013, p. 3)

Although all language production and comprehension reflect an integration of syntax and semantics, and although the multidimensional complexity of both syntax and semantics is vast, especially as it links to pragmatics, study of anaphora allows focus on specific computation which engages specific and well-studied aspects of both syntax and meaning, thus allowing more refined and tractable empirical study.

In a previous paper (Lust, Flynn, Henderson, Gair & Cohen Sherman, 2024, henceforth LFHGS24), part of a larger project studying language in prodromal Alzheimer’s Disease (AD), we reported experimental study of sentences such as 2 with adjoined temporal clauses and lexical pronoun subjects. Here anaphoric construal is necessary in order to determine the value of the pronoun ‘he’; until that value (or a range of values) is assigned to the pronoun, sentence meaning cannot be fully composed. In sentences like 2, construal can be computed through sentence syntax or through external reference. Our results revealed a systematic deficit in production of these sentence types in an amnestic Mild Cognitive Impairment (aMCI) population. We argued that the source of this deficit lies in the nature of anaphoric construal allowed in these sentences, reflecting deterioration at the CI interface of the Language Faculty.

In this paper, we extend our research program to ostensibly similar sentence types involving arguments which are phonetically null, traditionally termed “Control” structures, such as 3.

As shown through an extensive history of investigation (Green, 2018; Landau, 2013, 2021, 2024a; Williams, 1992), sentence types such as 3 reflect similar anaphora construal options to those in 2. They allow an option for context dependent as well as sentential syntax determined anaphora, as in 4.

Pronominal anaphora in sentence types such as 2 have been the source of decades of theoretical study, in philosophy (e.g., Geach, 1962) and linguistics, grounding our inquiry (e.g., Everaert & Reuland, 2023; Heim & Kratzer, 1998; Reinhart, 1983a, 1986, 2006; Reuland 2011a, among many others, explicated under a Binding Theory module in the LF). Study of language acquisition has complemented this research (e.g., early papers in Lust, 1986 and forward.)

Sentence types such as 3 have also been studied extensively, mainly as a reflection of “a distinct Control module in the theory of grammar” (Chomsky, 1995, p. 110), with debate regarding their representation continuing in current Minimalist approaches to generative theory (e.g., Chomsky et al., 2023, p. 60, section 8.1; Landau, 2024a). In a comprehensive theory of adjunct control (Landau, 2021, p. 199f), two forms of anaphoric construal have been revealed in these Control sentences. In contrast to Obligatory Control (OC), Non Obligatory Control (NOC) interpretations allow reference to context. Both types of control (OC and NOC) can occur in the same domain. “…OC and NOC…readings (of alternating adjuncts) may coexist…” (Landau, 2021, p. 176; 2024a). “NOC does arise under a c-commanding subject” (Landau, 2021, pp. 50, 84, 151). This research adjusts earlier views which assumed that “all or most adjuncts fall under OC [Obligatory Control]” (Landau, 2021, p. 2; see, e.g., Green, 2018; Landau, 2013, 2015, 2021, p. 199f, 2023, 2024b; Williams, 1992, on adjunct control). See also the Appendix to this paper. Control has also been studied extensively in language acquisition (e.g., Cairns et al., 1993, 1994; Gerard & McDaniel, 2025; Landau, 2021, Chapter 12; Sherman, 1983; Sherman & Lust, 1993a, 1993b, 1986).

In this paper, we investigate whether sentences such as 3 with null arguments also reveal significant language deterioration in aMCI, as did sentences with lexical pronominals such as 2. If the deterioration in sentences such as 2 is explained by deterioration in anaphoric construal, then it should replicate in sentences which reflect similar anaphoric construal options regardless of phonetic variations in proform, as in 3. By comparing results with null arguments (Control Theory) to those with lexical pronouns (Binding Theory) we not only test for replication of the aMCI deterioration discovered in lexical pronominal anaphora but also seek to refine our understanding of its nature.

We first (3.1) consider the LF as it provides an architecture for anaphoric construal at the interface between syntax and the semantic-pragmatic dimension of language knowledge. We (3.2) briefly review our previous experimental results reported in LFHGS24 with lexical pronouns in aMCI which revealed selective effects of dual anaphoric construal types in language deterioration. In (3.3) we consider the motivation for and challenge of extending this experimental work to the study of null proforms and in (3.4) we provide our leading experimental hypothesis. In (4) we review the design and method of our new experiment to study sentences with null proforms such as 3 and in (5) report results. (6) provides discussion and (7) conclusions.

As we recognized in LFHGS24, given a long history of linguistic analyses, lexical pronouns, e.g., 2, are essentially ambiguous. Two distinct types of anaphoric construal determine pronominal interpretation in sentences like 2: ‘Binding’ and ‘Coreference’ (see, e.g., Evans, 1980; Hust & Brame, 1976; Keenan, 1971; Reinhart, 1983a, 1983b, 1986; Reuland & Everaert, 2001; Reuland, 2011a, pp. 27-30, for review; see Everaert et al., 2010, for studies relevant to their psychological reality). This research has been complemented by an extensive history of study of their semantic representation (e.g., Heim & Kratzer, 1998), and by cross linguistic investigation (e.g., Lust, Wali, Gair & Subbarao, 2000). Accordingly, it has been complemented by continual psycholinguistic inquiry.

Each anaphoric construal type accomplishes a unique form of relation between antecedent and proform, and accordingly between pronoun and reference to context. In construal by ‘Coreference,’ computation reaches outside of the syntax of sentence composition; a specific reference is determined and assigned to the pronoun in accord with the context of the sentence.¹1

The distinction between “Binding and Coreference” has been broadened to define a distinction between “binding and non-binding” (rather than between ‘binding and coreference’) in order to recognize cases of co-valuation where reference is not involved in anaphora (cf. Heim & Kratzer, 1998; Reinhart, 2006, p. 172f; Reuland, 2011a). Here we will maintain the term ‘coreference’ to reflect non binding, both because it is used in much of the psycholinguistic literature, but also because co-valuation implies some form of cognitive computation external to sentence syntax.

Thus, as we assumed in LFHGS24, “…at the C-I [conceptual-intentional] interface pronouns can be translated either as expressions receiving a value directly from discourse storage or as variables to be bound by an antecedent” (Reuland, 2001, p. 447).

Based on the most fundamental property of the LF, structure dependence, Binding and Coreference are in an inverse relation syntactically and semantically.²2

In search for epistemological primitives, we assume a simplified, minimal definition of ‘c-command,’ setting aside issues of locality, which we will assume reflect a distinct component of grammar: “a c-commands b if a is a sister to a category γ containing b. Schematically: [a [γ … b …]]” (Reuland, 2011a, p. 29, #23). We assume that structure dependence is the most fundamental property of the Language Faculty. The configurational property of c-command is its essential defining property.

The fact that pronouns may be bound or free (not bound) reflects a fundamental structure dependent dissociation of two forms of syntax-semantics/pragmatics relations.

We assume that this non necessary dissociation of construal types is determined by the architecture of the Language Faculty (LF).⁴4

Reinhart (2006) makes a distinction between ‘syntactic binding’ and ‘logical binding.’ We focus here on ‘syntactic binding,’ using the term to connote its configurational determination. More fundamentally, we focus on the epistemological primitives which underlie the Binding/Coreference distinction (cf. Reuland, 2011b).

Structure dependent access to both Bound and Coreferential (“sloppy” and “strict”) readings in pronominal anaphora have been attested from early language acquisition to adulthood (e.g., Foley et al., 2003; Foley, Lust, Battin, Koehne & White, 2000).

Without Binding

When pronouns are not bound, they are free, i.e., their interpretation is in principle limitless and multifaceted, engaging various forms of cognition.⁵5

The role of pragmatic context in sentence processing of anaphora is long established (e.g., Caramazza et al., 1977; Hankamer & Sag, 1976).

In contrast, anaphoric construal by Syntactic Binding obviates context dependence within anaphoric construal.

In an ongoing interdisciplinary and inter-institutional project (Cornell University, Massachusetts Institute of Technology, Massachusetts General Hospital), we have begun to assess the role of the Language Faculty and its integration with other systems of the mind in prodromal AD; aspects of thought and neural deterioration have been studied. Language in individuals who are experiencing deficits in various aspects of cognitive functioning, compared to those in whom cognition is preserved, provides a window into the CI-Interface (Conceptual-Intentional) of the Language Faculty, complementing study of the LF in language acquisition (e.g., Cordella et al., 2015; Lust et al., 2015a, 2015b, 2017, 2019, 2024; Sherman et al., 2020, 2021; see also Chapin et al., 2022; Hinzen et al., 2018; Moro et al., 2001; Vasić, 2006).

We focus on the prodromal stage of AD referred to as aMCI, a period between normal aging and progression to AD (Petersen, 2003, 2004). It is characterized by cognitive loss relative to baseline, with predominant decline in memory (particularly the amnestic type of aMCI) although other cognitive areas may be involved. Individuals at this stage maintain the ability to independently manage most activities of daily living.⁶6

MCI is a complex condition which is difficult to diagnose and depends on careful clinical exam. Although it is a “probable” predictor of clinically manifest Alzheimer’s Disease, it is not necessarily so. In our current project we focus on aMCI because it has the highest probability among several forms of MCI of progression to AD (Mattke et al., 2023; Petersen, 2003).

The non necessary dissociation in sentence production which is revealed in previous experimentation begins to localize the source of an aMCI language deficit, implicating the role of anaphora construal type. It leads us to replicate this deficit and to pursue its nature. We can first ask: to what degree is the lexical pronoun itself a source of deficit on sentences such as 2? If our previous results documenting deficit in sentences like 2/8 could be attributed to some aspect of lexical pronoun usage in aMCI, this would potentially obviate the relevance of anaphoric construal type.

If, as we have proposed, aMCI deficit lies in anaphoric construal at the LF interface, then we would predict that it would generalize beyond language-specific variation in anaphora representation, such as whether proforms are lexical or null, i.e., beyond the specific morphology or lexical form which construal may involve. If, as research has shown, sentence types such as 3/13 do in fact allow both a Coreferential type and a Binding type, an OC or a NOC, construal and if an option for a non Binding (context dependent) type anaphoric construal is the basis for the selective aMCI deficit discovered in LFHGS24, then we would expect aMCI to demonstrate significant deterioration relative to healthy adults, on sentences such as 3/13 with null subjects, Control sentences, as they did on sentences like 2/8 with lexical pronouns.

Using experimental designs, we compared language production of three groups: amnestic Mild Cognitive Impaired (aMCI) (N = 22), Healthy Aging (HA) (N = 24), Healthy Young (HY) (N = 10). (See Table 1). All data collection was approved by Institutional Review Board regulations at each institution. All completed a 42-question sociodemographic questionnaire.

Our test of Control sentences was administered among a series of linguistic tests. The series included temporal Adjoined sentences with lexical pronoun subjects and Coordinate sentences, both reported in LFHGS24, and Relative Clause structures, reported in Sherman et al. (2021) and Lust et al. (2015a, 2017).

In addition to linguistic tests, all groups, MCI, HA and HY, were also tested on two standardized cognitive measures: Addenbrooke’s Cognitive Examination-Revised (ACE-R), a multidomain cognitive screen (Mioshi et al., 2006) and Brown Peterson Consonant Trigram task (BP), a test of Verbal Working Memory (Belleville et al., 2007; see Sherman et al., 2021, p. 4298, for details of ACE-R and BP results across groups, and Sherman et al., 2026, for extended cross-experiment analyses). In accord with clinical population categorization, MCI scores were significantly lower than both HY and HA for both ACE-R and BP.

There was a significant main effect of Group, F(2, 810) = 4.17, p = .02, as had been found for sentences with lexical pronouns (LFHGS2024). As shown in Figure 1, successful production of sentences declined in the aMCI group. Overall, across sentences, HY and HA did not differ significantly from each other: t(810) = 1.50, p = .134, x̄_Δ = .178. The aMCI group performed significantly lower than HY: HY vs. aMCI, t(810) = 3.39, p = .001, x̄_Δ = .428, and tended to perform lower than HA: HA vs. aMCI, t(810) = 1.94, p = .052, x̄_Δ. = .25).

Also replicating previous results with sentences with lexical pronouns, Semantic Plausibility had a significant effect on sentence imitation, significantly depressing performance, F(1, 810) = 18.01, p < .0001. At the same time, replicating results with lexical pronouns, there was no significant Group x Semantic Plausibility interaction, F(2, 810) = 0.26, p = .77, indicating that the Group effect was generally independent of plausibility. As Figures 2 and 3 show, a similar pattern of Group differences holds across the Semantic Plausibility variation.

In this experiment, where BD and PD are united and confounded, the BD/PD factor showed a significant overall effect, F(1, 810) = 12.28, p < .001 and did not interact significantly with Semantic Plausibility, F(1, 810) = 0.03, p = .869. A Group interaction approached significance at the .05 boundary F(2, 810) = 3.05, p = .048.

As can be seen in Figure 1, across all groups, Left Branching with Backward Proform (LBB) sentence imitations are more successful than Right Branching with Forward Proform (RBF). This reverses the result found for sentences with lexical pronouns (e.g., 8a and b), where RB sentences like 15a (=8a) were more successfully imitated than those like 15b overall (LFHGS24).¹⁷17

Conflating over pronun direction variation in sentences with lexical pronouns (LFHGS24).

As Figures 2 and 3 show, preference for LBB sentences with null subjects holds across groups both with and without Semantic Plausibility. At the same time, production of both RBF and LBB forms with null arguments is below 50% in aMCI across semantic conditions (RBF = .363, LBB = .469).

Qualitative analyses of aMCI sentence production confirm an underlying relation between anaphoric construal in null/nonfinite and lexical/finite adjuncts. Examples of types of aMCI reformations are shown in Table 4.

As summarized in Table 5, analyses of the components of anaphoric construal in the Control sentences, i.e., the NP antecedent and pro-form, showed that for aMCI, as for all groups, more reformations were made on the NP than on the null pro-form. This result resembles the pattern previously reported for finite sentences with lexical pronouns in LFHGS24 and suggests that, in general, an anaphora relation is being pursued in both cases: an antecedent must be identified for anaphoric construal.

At the same time, as Table 5 shows, there were more changes to the null than to the lexical pronoun subject in both aMCI and HA. aMCI individuals frequently changed the null subject to a lexical pronoun and simultaneously the nonfinite to a finite adjunct, as in 17a, b (examples 5–8 in Table 4). aMCI individuals changed the null pronominal in 19.57% of their reformations. This occurred even when individuals showed difficulty maintaining the lexical material in the sentence, as 17b and examples on Table 4 show. Although some conversions of lexical pronouns to null arguments in adjuncts has been reported (LFHGS24), such changes were minimal (contributing minimally to 2.84% of pronoun conversions). The productive conversion from null to lexical pronominals also contrasts with previous findings for coordinate sentences, e.g., 17c, in which aMCI individuals productively reduced the lexical pronoun to a null form; 41% of items, 95% of errors (LFHGS24, p. 33).

Changes from a null subject to a lexical pronoun mainly occurred in the RBF adjuncts, as in 17a or b, accounting for 22.4% of aMCI errors on these RBF sentences. 90% of these conversions appropriately converted a nonfinite clause to a tensed clause, indicating a link between clause finiteness and pro-form type (null or lexical pronoun¹⁹19

Although we do not pursue this issue here, explanation of the difference in left branching/preposed sentences may be assumed to involve the representation of left branching/preposed structures in general (e.g., Kayne, 1994), and to the nature of an anaphoric ‘forward directionality’ preference linked to lexical pronouns in right branching.

Notably, although there were few errors overall in the Healthy Young group, pronoun insertions were also observed in this group, as in 18.

Through these conversions in RBF cases such as 17 or 18, individuals demonstrate a directionality effect consistent with lexical pronouns. A forward anaphora preference is well-known and well-studied in association with lexical pronouns. In this experiment we see a complementary relation with null subjects: production of sentences with forward null arguments is reduced in favor of forward pronoun production in adjunct domains.

These reformation data confirm a relation between null and lexical pronominal anaphora in temporal adjuncts, as well as a tendency toward generalization to a lexical pronominal and a finite domain. The correlation of pronominal form and clause finiteness confirms that this relation is grammatical and structure dependent. The apparent contrast in the role of directionality in Control sentences with null subjects is due to selective reformation in nonfinite RB sentences (not LB) towards a forward lexical pronoun and rightward finiteness. Thus, the finite/lexical pronoun and nonfinite/null pronominal results cohere.

Table 6 exemplifies production by three aMCI participants across different sentence types, contrasting their performance on the Control sentences in this current study to that across experiments in our wider program. Production success within each individual varies across anaphoric construal types.

Each individual’s production is compared on (6A) null and lexical pronominal sentences in temporal adjuncts, where both Binding/Control and Coreferential/NOC construals are possible, on (6B) Binding Principle C sentences where anaphoric construal is disallowed, and on (6C) Coordinate Sentences where only Binding is available in the null forms in contrast to lexical pronouns. As the examples suggest, temporal adjunct conditions (both null and lexical) where both types of construal are possible (6A), both provoke incorrect productions, in contrast to success with the 6B and 6C sentence types, conforming with Group statistics.²¹21

Statistical analyses are based on Group populations, assuming and correcting for variance within Group. Not all individuals reflect within themselves the patterns reflected in significant Group differences; however, some do. We have demonstrated this in 3 individuals in Table 6.

As the examples show, production of both the temporal adjuncts (lexical and null) is exceptionally difficult for these aMCI individuals. See for example participants’ poor sentence production in null and lexical pronominal conditions in adjuncts, compared to their successful performance on the Principle C sentence and Coordinate sentence with null argument. Productive reduction of the lexical pronoun in Coordinate Sentence to a null argument (where Binding results) contrasts with the conversion of the null form to a lexical pronoun in temporal adjuncts (where both CR and Binding/OC and NOC construal types are options). Since all sentences across all conditions were equally controlled in factors such as length and lexical frequency, these results provide evidence that both language production success and reformations are modulated by anaphoric construal possibilities of the model sentence. They do so both within group statistics and within individuals.

In this experiment, aMCI production of Control sentences, i.e., nonfinite temporal adjuncts with null subjects, is significantly depressed compared to HY and HA, as it was for comparable finite sentences with lexical pronouns (LFHGS24). This confirms our leading hypothesis that temporal adjuncts with null subjects would also challenge aMCI, given their shared option for dual anaphoric construal types (Coreference and Binding, NOC and OC).

This shared deficit contrasts with sentences in our wider program which reflect Binding, e.g., Principle C or Coordinate VP ellipsis without dual construal options, where aMCI individuals are relatively successful in sentence production (LFHGS24).

Qualitative analyses confirm that participants related lexical pronominal (finite) and Control (nonfinite) sentence types. aMCI productively represented the nonfinite sentences with null arguments by converting them to lexical pronominalization and finite adjunction; according with shared construal types across these sentence types. Conversion of null to lexical pronoun would appear to reflect recognition of Coreference possibilities in the control domain. Comparison to results from our wider program confirms that this productive conversion from null to lexical pronominal forms distinguished the temporal adjunct domain.

Semantic Plausibility does not significantly interact in determining Group effects, suggesting that, as with lexical pronouns, the source of aMCI deficit in Control sentences lies, at least in part, in the syntactic factors involved in anaphoric construal, over and above their general semantic plausibility. A significant sensitivity to the (BDPD) factor in nonfinite sentences, independent of Semantic Plausibility, confirms that construal is structure dependent, as it was in the finite sentences in our previous study.

These results confirm that an aMCI language deficit selectively targets sentences involving an option for context- dependent anaphoric construal, generalizing across the differences between Control structures and finite adjuncts in their syntactic and phonetic/morphological representation. This deficit is thus not specifically linked to the pronominal form (lexical or null) in the clausal adjunct. Rather, it is linked to the computation of anaphoric construal which underlies both Control and lexical pronominal anaphora.

Given the existence of two forms of anaphoric construal, why are sentences with the option for Coreference/NOC selectively deficited?

Although aMCI deficit has been found to involve computation of anaphora, this deficit is not due to a general deficit in syntax. As we saw, while deficited on sentences like 2/8 or 3/13, individuals with aMCI are not similarly deficited on comparable sentences with no anaphoric construal, e.g., 12; as we saw, or on sentences reflecting Binding, as reflected in Principle C effects, e.g., 9 (LFHGS24, 2017; Sherman et al., 2021).

Cognitive limitations of aMCI such as memory also are not a general explanation for our linguistic results (Sherman et al., 2021, 2020, 2026). As we noted, tests of memory (i.e., ACE-R, or Brown-Peterson) have not shown significant correlations with aMCI linguistic performance.

Given the complexity of computation of reference in 3.1, it would appear to follow that deficit in Coreferential and context- dependent computation must be involved in an explanation of the aMCI deficit. However, there is no general indication of a correlated failure in specific reference required by nominals. Independent tests of Naming or Semantic Fluency measured on the ACE-R (Sherman et al., 2021, 2020, 2016, 2013, 2026) have failed to predict the observed language deficit. Significant success on lexically headed relatives (in contrast to free relatives), e.g., 11 (Lust et al., 2017; Sherman et al., 2021), also suggests that deficit does not lie simply at the level of specific reference. Principle C sentence, e.g., 9, production is highly successful although these sentence types include indeterminacy of pronoun reference. Success with Principle C sentences does not require integration of the pronoun in anaphoric construal, suggesting that source of deficit does not lie in the referential properties of the pronoun in particular, but relates specifically to integration of anaphoric construal in sentence syntax.

“Reference Set” Challenge: Dual Anaphora Options

As we noted in our previous paper LFHGS24 (p. 17), it is possible that the deficit we have observed is not simply due to the challenge of Coreferential or context dependent construal itself but to the challenge of the availability of dual modes of construal at the interface; (Binding/OC) and (Coreference/NOC). This would reflect what has been called a “reference set” challenge at the interface of the Language Faculty with general cognition (Reinhart, 2006). Our experimental sentences, e.g., 2/8 or 3/13, allow both types of construal equivalently in the same sentence.

As we argued in LFHGS24, while our data may reflect an interface challenge involving dual anaphoric construal types, they do not support current representations of proposed mechanisms for ‘reference set’ computation. For example, they do not support memory of, and choice between, two distinct potential interpretations of pronominal reference in a given sentence (e.g., Reinhart, 2006). Since there was no discourse context presented in the EI task, there was no necessity for determination of specific discourse referents and no evidence that speakers did so or tried to do so. Thus, there is no evidence for competing construal options based on their specific reference. Critically, the EI task on which our language data are based continually reflects participants’ creative integration of meaning and form, as seen in their reformations, but does not require, and does not reflect, generation of specific reference in representation of sentence meaning.²²22

These results support the shift from the original “Coreference” construal type label to “covaluation.”

Thus, while our results confirm that an interface challenge exists, they suggest that this challenge is not based on referential properties of lexical pronominal forms. Our current results which involve null pronominals in Control structures accentuate the need to recognize, but redefine, this interface challenge.

Tentative Resolution

Although it is not possible to resolve our leading question without further research, our data lead us to pursue the architecture of the Language Faculty as it both invites and constrains the interface of language with thought. While the architecture of the LF structures two possible forms of anaphoric construal, i.e., two ways in which language integrates with thought, it does not resolve choice between the two. It does not determine specific behavior; it does not resolve optional construal type.

Given our results, we assume that the Binding Theory module of the LF determines construal by Binding and its inverse equivalently, and is always available. The structure dependence of Binding defines both what is possible and what is not. aMCI individuals, like cognitively normal adults, show continuous structure dependence. At the same time, the capacity for external reference is also always available, providing the competence for Coreference or NOC.²³23

The inverse function of Binding necessitates free reference. These results also motivate renaming of the ‘reference set’ challenge.

Cognitive weakening in aMCI may lie in weakened ability to associate these cognitive extensions to the linguistic structure of anaphoric construal. aMCI language deficit may lie in weakening of inter-modular association, not in language itself, not in syntactic Binding, not in cognitive reference itself.

Binding resolves a potential conflict between internally and externally determined anaphoric construal types; non Binding conditions do not. When a Binding structure provides a potential for obligatory binding, that option is taken, as in pronoun reduction in VP ellipsis, e.g., 16c. When it does not, as in temporal adjunctions, both options remain. Non Binding construal engages a weakening cognitive competence attested in cognitive impairment. When the structure of Binding (as in Principle C) prevents anaphora construal, e.g., 9, the language production deficit is avoided (See Table 6).

This tentative proposal recognizes the empirical reality of a ‘reference set’ challenge at the LF interface (Reinhart, 2006). However, it suggests that the challenge is solved at the level of the architecture of the interface, not at the level of processing of individual construal types, or of ‘efficiency’ principles to resolve choice between them. Current clinical study in the area of aMCI coheres with this approach; it suggests that cognitive deficit in MCI may reflect weakening of inter-modular cognitive associations more generally (Sherman et al., 2020, 2026). We suggest that ‘reference set ambiguity’ is in fact not an exceptional instance to be resolved at the LF interface but is in fact a reflection of the essential nature of the architecture of the Language Faculty.

Given this approach to explanation of aMCI deficit, further analyses of the clinical deficit we have discovered in language production now requires further linguistic analyses of the language we measure.

We may first ask what the knowledge is that underlies the dissociation which both Control Theory and Binding Theory recognize, i.e., that between OC and NOC, in Control Theory, and Binding and Coreference, in Binding Theory (see Landau, 2013, pp. 54-58; 2021, pp. 183-84).²⁴24

In early work, Manzini (1983, p. 421) argued that “…control is an essentially configurational phenomenon and control theory an essentially configurational theory: in particular, control theory is constructed on essentially the same notions on which binding theory is constructed…” (see also Koster, 1984; Manzini & Roussou, 2000; McFadden & Sundaresan, 2018).

If these dissociations both reflect an essential design feature of the Language faculty which is structure dependent and which overrides language-specific phenomena such as morphology (of pronominal form) and inflection (finiteness), then we are led to pursue the representation of a grammatical core; one which provides fundamental constraint on knowledge, acquisition and loss. As Landau (2021, p. 184) summarizes, our challenge is “to highlight the similar ways in which competition between two strategies – one syntactic or at least LF [Logical Form]-visible, and the other pragmatic, related to reference tracking in discourse plays out both in the binding module and in the control module… Finding such parallels across empirical domains is a promising sign that a fundamental design feature of language is at work” (cf. Landau, 2021, 199f; see Landau, 2024b, for review and discussion in terms of a general Control Theory).

As sketched in Figure 4, both BT and CT reveal the fundamental dissociation between two types of dependency: syntactically determined and context dependent. Both integrate some form of c-command in this dissociation; both involve a variable differentiated as bound or free accordingly. Both engage a range of contextual effects in long distance domains, i.e., non local Binding, or NOC. Both apply over both lexical and null proforms.

Syntactic factors distinguish adjunct Control as they do Binding. In OC, the controller “must be an argument of the clause immediately dominating the adjunct” (Landau, 2021, p. 21). In Binding Theory, structural locality determines lexical anaphor Binding. In this way, both Binding and Control distinguish long distance (cross clausal) dependencies.

Given the epistemological framework in Figure 4, any one or more of factors 6.3.1-6.3.6 may be crucial in determining the nature of the selective aMCI language deficit our experimental work has revealed.

Empirically, given the wide variance in any population of normal Healthy Aging, or of MCI (e.g., Corbo & Casagrande, 2022; Ganguli et al., 2004; Mattke et al., 2023), larger populations must be studied now in order to validate and generalize our program results. Longitudinal study is necessary to evaluate their predictiveness. Comprehension tests can provide converging evidence to our production tests. If there is in fact a Language Faculty substrate for selective deficit in aMCI language as we have hypothesized, then comparative cross linguistic research must be conducted, as well as comparative studies of language acquisition.

Theoretically, while our interpretation of our results has been framed in terms of the architecture of the LF, specifically its interface, it leaves undefined the implementation, linguistic and/or psychological, by which anaphora type resolution is selectively weakened in MCI. We leave to future research the draft of a comprehensive model of cognitive language-thought relations, structured by specific constraints of the Language Faculty CI Interface.

In the end, an essential mystery remains regarding the essential deficit which our experimental program has revealed to date. An option for a Coreferential or NOC anaphoric construal selectively depresses success in sentence production in aMCI. It does so even when an actual referential interpretation of the sentence is not attempted. The architecture of the Language Faculty simply provides the structure dependent possibility for it. Future study is necessary for resolving this mystery.