2. Experiment 1

2.1. Method

2.1.1. Participants

Twenty-eight volunteers participated in the experiment, recruited either via a recruiting platform of the University of Tübingen or via local social networks. Twenty-five participants were right-handed and three left-handed (8 male, 20 female), and they had a mean age of 23.8 years (SD = 4.6 years). According to their self-report, all participants were native speakers of German. The experiment was run in accordance with the World Medical Association’s Declaration of Helsinki 2008, and all participants provided written informed consent prior to the experiment. Participants received course credit or financial compensation in the form of a book voucher (€15) for their participation.

2.1.2. Apparatus

The experiment was programmed in PsychoPy3 (version 2020.1.2, https://www.psychopy.org; Peirce et al., Reference Peirce, Gray, Simpson, MacAskill, Höchenberg, Sogo, Kastman and Lindelov2019) and was conducted online via the platform Pavlovia (https://pavlovia.org/). Participants accessed the experiment via a link and used their own computer, and they provided demographic data and informed consent via e-mail. The behavioral data were initially stored anonymously on a server in the UK. Demographic data and informed consent were provided via email.

2.1.3. Material

For both sentence sets (set 1, memory context; set 2, inference context), we created short discourse contexts that consisted of five spoken German sentences followed by a test sentence (Tab. 1). The first context sentence (1) introduced an everyday scenario such as hiking or tidying up. The second context sentence (2) contained a first noun phrase (NP1) which established either the existence of an object by means of an indefinite determiner (a – in German ‘ein’) or the non-existence of an object by negating the object’s presence (no – in German ‘kein’). The third (3) and fourth (4) context sentences were used to describe the contextual scenario in more detail. The fifth context sentence (5) contained a second noun phrase (NP2). This NP2 (i) established the existence of the second object if NP1 was negated or (ii) negated an object’s existence if NP1 was introduced as an existing object. The sixth sentence served as a test sentence (6).

Table 1. Examples of sentence material originally presented in German. In sentence set 1 (memory context, left column), a referent was explicitly mentioned in the context by an indefinite NP (intact PSP) or by a negated NP (violated PSP) and was presented at close or far distances relative to the PSP trigger in the test sentence. In sentence set 2 (inference context, right column), the context was either plausible or implausible for a potential referent that was not explicitly mentioned. The PSP trigger in the test sentence could be either an indefinite NP (intact PSP) or a definite NP (violated PSP).

In sentence set 1 (memory context) (see Table. 1, left column), the test sentence described an action of a protagonist with the object mentioned in the context by either NP1 (in sentence 2) or by NP2 (in sentence 5). To monitor PSP reference processes, the PSP of the NP was either intact or violated (psp consistency). In more detail, as the PSP trigger in the test sentence of this set was always a definite NP, the PSP was intact when the definite NP in the test sentence referred to the existing NP in the context (intact existing PSP), and it was violated when the definite NP referred to the negated NP in the context (violated existing PSP). Memory requirements were varied by the distance between the PSP trigger in the test sentence and the position of the contextual NP (distance), which was presented either in context sentence 2 (far) or in context sentence 5 (close). Altogether, the two factors were combined for each context sentence set, resulting in four conditions for each context: There were two conditions with an intact existence PSP, i.e., the establishment of an object by the indefinite NP in the context at far and close distance combined with an indefinite NP in the test sentence, and two further conditions violating the existence PSP by negating the existence of an object at far and close distance also combined with an indefinite NP in the test sentence. These four conditions were realized for the two different discourse NP (NP1, NP2), resulting in eight trials per scenario. As we established eight different scenarios, 64 trials for sentence set 1 were presented.

In sentence set 2 (inference context) (see Table 1, right column), the object mentioned in the test sentence never occurred in the context scenario. Here, we manipulated PSP consistency by using either an indefinite or a definite NP in the test sentence. In this situation, the novelty PSP of the indefinite NP was intact as the object had not been mentioned, and a new object was introduced (intact novelty PSP). In contrast, the existence PSP of the definite was violated when the definite NP referred to a previously unmentioned object (violated existence PSP, psp consistency). Memory requirements in this set were modulated by establishing either a plausible or an implausible semantic context for the object mentioned in the test sentence (plausibility). For this sentence set 2 (inference context), we built 16 new scenarios containing a test sentence with either a semantically plausible or implausible object with respect to the context. The combination of context sentences with the plausible test sentence object of another scenario from sentence set 2 served as implausible discourses. Each test sentence object in this sentence set occurred four times: with a definite determiner, with an indefinite determiner, and in a plausible and implausible semantic context, resulting in 64 trials for the 16 different scenarios. In addition, eight practice trials were constructed that contained different discourse scenarios than those in the experimental trials, but the same discourse structure as in the sentence set 1 (memory context) and set 2 (inference context).

Each discourse, including the test sentence, was spoken on tape condition as one unit by a female actor with consistent prosodic modulation to maintain a natural flow of speech without discontinuity effects.

2.1.4. Procedure

Participants were instructed to complete the experiment on a computer. They were asked to use the computer’s built-in speakers and to sit in front of the computer. After a short on-screen briefing on the experimental procedure, eight practice trials similar to the experimental ones were presented to familiarize participants with the experimental procedure. The time course of a single trial is shown in Figure 1.

Figure 1. Illustration of an exemplary trial. A red fixation cross indicated the start of a trial and was visible for the entire duration of the audio presentation. After a further 2,500 ms, the red fixation cross was replaced by a green fixation cross, signaling participants to judge the coherence of the discourse. The green fixation cross disappeared when the response was given and a new trial began after 2,000 ms. If no response was made within 6,500 ms, a prompt (“Please press a key”) appeared on the screen, which disappeared when one of the response keys was pressed.

Participants were asked to look at a red fixation cross in the center of the screen while listening attentively to the discourse consisting of five context sentences and one test sentence. 2,500 ms after the end of the discourse, the fixation cross turned green, and participants rated the coherence of the test sentence relative to the context sentences (“How well does the test sentence match the context?”) on a Likert scale from 1 to 4 (1 = poor, 2 = fairly poor, 3 = fairly good, 4 = good). It was made clear that “coherence” refers to the logical and coherent connection of information between the discourse sentences. To ensure that the participants understood the concept of coherence, they were given examples of coherent and incoherent discourses. Participants answered by pressing keys on their computer keyboard with their index and middle fingers of the two hands: Q key with left middle finger = good (4), W key with left index finger = fairly good (3), O key with right index finger = fairly poor (2), P key with right middle finger = poor (1). For half of the participants, the left/right assignment to the rating scale was reversed. If no response was made within 6,500 ms, a prompt (“Please press a key”) appeared on the screen, which disappeared when one of the response keys was pressed. Only when a response was made, the trial continued, the green fixation cross disappeared, and a new trial began after 2,000 ms.

The experiment lasted approximately 70 minutes. The total sentence material of 128 trials was divided into eight blocks of 16 discourse scenarios each, to allow participants to take a short break after each block. For half of the participants, the first four blocks contained only trials of sentence set 1 (memory context), and the following four blocks contained only trials of sentence set 2 (inference context) and this order was reversed for the other half of participants. Within a block, trials were presented in a pseudo-random order that assured that each condition was presented four times and that all scenarios were different from each other.

2.1.5. Data analyses

Statistical analyses of the coherence judgment data were performed using R 4.4.1 (R Core Team 2024). We performed separate statistical analyses for sentence set 1 (memory context) and set 2 (inference context). Coherence judgments were analyzed by means of cumulative link mixed models (CLMMs) with a logistic linking function – a method appropriate for repeated measures data resulting from a Likert scale (Stroup, Reference Stroup2012, Taylor et al., Reference Taylor, Rousselet, Scheepers and Sereno2023). We used the clmm ordinal and emmeans package in R as suggested by Christensen (Reference Christensen2023). In addition to the estimated marginal means (EMM) and standard error (SE), we also reported the original means (M) and standard deviation (SD) without plotting them to illustrate the extent to which participants used the extreme ends of the scale. Our fixed effects for sentence set 1 (memory context) were DISTANCE and PSP CONSISTENCY, with an interaction between them. Our fixed effects for sentence set 2 (inference context) were plausibility and psp consistency, with an interaction between them. Furthermore, for both sentence sets, we included both participants and discourse scenarios (items) as random effects because we expected differences in the extent to which they are affected by our experimental manipulations. To derive an appropriate random effects structure with comparable complexity across sentence set, we took the following approach: We fitted the CLMMs following Brown (Reference Brown2021), so that the models did not show convergence warnings or singular fits, both of which indicate problems with parameter estimation. This involved fitting the most complex model first and gradually removing terms until convergence was reached. Accordingly, for sentence set 1, we started with fitting a CLMM with (i) correlated by-participant random intercepts and slopes for distance and psp consistency and (ii) correlated by-item random intercepts without slopes. For sentence set 2, we started with fitting a CLMM with (i) correlated by-participants random intercepts and slopes for plausibility and psp consistency, and (ii) correlated by-item random intercepts without slopes. For sentence set 1 (memory context), a model with interaction between the by-participant random slopes for the two factors showed a better fit (vs. without interaction).Footnote ¹ For sentence set 2 (inference context), however, a model without interaction between the by-participant random slopes for the two factors is sufficient to describe the data.Footnote ² To make the models comparable, we chose the model with the more parsimonious random effects structure, that is, without interaction between the by-participant random slopes for the two factors for both sentence sets. Removing the interaction for set 1 (memory context) makes no difference to the fixed effects. In case of significant interaction effects, we conducted post-hoc tests based on contrasts using the Wald-z-statistic, for which we report Bonferroni corrected p-values for four tests each.

2.2. Results

Figure 2 shows the estimated marginal means (EMM) and standard error (SE) for the coherence judgments for sentence set 1 (left panel) and set 2 (right panel). In sentence set 1 (memory context), intact PSPs were judged to be more coherent (EMM = 2.66, SE = 0.28) than violated PSPs (EMM = −2.36, SE = 0.31), β = −5.81, SE = 0.58, z = −10.09, p < .001 (psp consistency). Moreover, the effect of distance was not significant, β = −0.27, SE = 0.30, z = −0.90, p = .371 (close distance: EMM = −0.1150, SE = 0.17; far distance: EMM = 0.41, SE = 0.16). The interaction psp consistency × distance, β = 1.57, SE = 0.32, z = 4.88, p < .001, however, shows that distance modulated the consistency effect. Violated PSPs were judged to be less incoherent if they had a far referent (EMM = −1.71, SE = 0.32) than if they had a close referent (EMM = −3.01, SE = 0.36), β = −5.81, SE = 0.58, z = −10.09, p_Bonf. <.001, whereas for intact PSPs there was no difference between close referents (EMM = 2.80, SE = 0.31) and far referents (EMM = 2.53, SE = 0.32), β = −0.27, SE = 0.30, z = −0.90, p_Bonf. =.371. The mean (M) and standard deviation (SD) of the original Likert scale coherence ratings (1 = poor and 4 = good) for sentence set 1 were as follows: intact PSPs with close distance, M = 3.62, SD = 0.49; intact PSPs with far distance, M = 3.56, SD = 0.50; violated PSPs with close distance, M = 1.37, SD = 0.51; violated PSPs with far distance, M = 1.80, SD = 0.60.

Figure 2. Estimated marginal means of coherence judgments as a function of psp consistency (intact vs. violated). In sentence set 1 (memory context, left panel), the reference information was presented at close or far distance (distance), whereas in sentence set 2 (inference context, right panel), the context was either plausible or implausible for a potential referent (plausibility). Error bars represent the standard error based on the variance of the residuals and the structure of the model. It takes into account the uncertainty in the estimates resulting from the data and the model. Asterisks indicate threshold significance *** <.001, n. s. = not significant for (i) four post hoc tests (intact PSP: close vs. far; violated PSP: close vs. far; close distance: intact vs. violated; far distance: intact vs. violated) using the Wald-z-statistic (set 1, left panel) and (ii) the two main effects for psp consistency and plausibility (set 2, right panel).

In sentence set 2 (inference context), there was no significant effect of psp consistency, β = −0.17, SE = 0.19, z = −0.89, p = .372 (intact PSPs: EMM = 0.06, SE = 0.19; violated PSPs: EMM = −0.11, SE = 0.18). Moreover, plausible relationships (EMM = 2.08, SE = 0.23) were in general judged to be more coherent than implausible ones (EMM = −2.13, SE = 0.22), β = −4.21, SE = 0.31, z = −13.54, p < .001 (plausibility). There was no significant interaction between psp consistency and plausibility, β = 0.11, SE = 0.37, z = 0.29, p = .773. The mean (M) and standard deviation (SD) of the original Likert scale coherence ratings (1 = poor and 4 = good) for sentence set 2 were as follows: intact PSPs with plausible relationships, M = 3.35, SD = 0.29; intact PSPs with implausible relationships, M = 1.68, SD = 0.28; violated PSPs with plausible relationships, M = 3.27, SD = 0.37; violated PSPs with implausible relationships, M = 1.64, SD = 0.33.

3. Experiment 2

In this experiment, we tested the hypothesis that a priory knowledge about discourse structure had prevented processing of PSP consistency in sentence set 2. To this end, we intermixed the two sentence sets so that participants could not foresee which type of sentence set was presented.

3.2. Results

Figure 3 shows the estimated marginal means (EMMs) for coherence judgments for sentence set 1 (left panel) and set 2 (right panel). In sentence set 1 (memory context), intact PSPs were judged to be more coherent (EMM = 2.86, SE = 0.28) than violated PSPs (EMM = −2.29, SE = 0.35), β = −6.07, SE = 0.57, z = −10.56, p < .001 (psp consistency). Moreover, close distances (EMM = 0.15, SE = 0.19) were, in general, judged to be less coherent than far ones (EMM = 0.42, SE = 0.17), β = −0.65, SE = 0.24, z = −2.74, p = .006 (distance). The interaction psp consistency × distance, β = 1.83, SE = 0.31, z = 5.84, p < .001, however, shows that distance modulated the consistency effect. Violated PSPs were judged to be less incoherent if they had a far referent (EMM = −1.70, SE = 0.35) than when they had a close referent (EMM = −2.88, SE = 0.39), β = −1.18, SE = 0.23, z = −5.19, p_Bonf. <.001. A reversed pattern was observed for the intact PSPs, which were judged to be less coherent if they had a far referent (EMM = 2.54, SE = 0.30) than when they had a close referent (EMM = 3.19, SE = 0.30), β = 0.65, SE = 0.24, z = 2.74, p_Bonf. = .025. The mean (M) and standard deviation (SD) of the original Likert scale coherence ratings (1 = poor and 4 = good) for sentence set 1 were as follows: intact PSPs with close distance, M = 3.69, SD = 0.55; intact PSPs with far distance, M = 3.53, SD = 0.50; violated PSPs with close distance, M = 1.45, SD = 0.59; violated PSPs with far distance, M = 1.86, SD = 0.53.

Figure 3. Estimated marginal means of coherence judgments as a function of psp consistency (intact vs. violated). In sentence set 1 (memory context, left panel), the reference information was presented at close or far distance (distance), whereas in sentence set 2 (inference context, right panel), the context was either plausible or implausible for a potential referent (plausibility). Error bars represent the standard error based on the variance of the residuals and the structure of the model. It takes into account the uncertainty in the estimates resulting from the data and the model. Asterisks indicate significance of threshold * <.05, *** <.001, n. s. = not significant for (i) four post hoc tests (intact PSP: close vs. far; violated PSP: close vs. far; close distance: intact vs. violated; far distance: intact vs. violated) using the Wald-z-statistic (set 1, left panel) and (ii) the two main effects for psp consistency and plausibility (set 2, right panel).

In sentence set 2 (inference context), there was no significant effect of psp consistency, β = −0.26, SE = 0.29, z = −0.90, p = .370 (intact PSPs: EMM = 0.01, SE = 0.22; violated PSPs: EMM = −0.33, SE = 0.22), mirroring the absence of a significant psp consistency effect in Experiment 1. As in Experiment 1, plausible relationships (EMM = 1.65, SE = 0.28) were judged to be more coherent than implausible ones (EMM = −1.98, SE = 0.30), β = −3.55, SE = 0.49, z = −7.29, p < .001 (plausibility). However, there was no interaction between psp consistency and plausibility, β = −0.17, SE = 0.41, z = −0.40, p = .689. The mean (M) and standard deviation (SD) of the original Likert scale coherence ratings (1 = poor and 4 = good) for sentence set 2 were as follows: intact PSPs with plausible relationships, M = 3.16, SD = 0.44; intact PSPs with implausible relationships, M = 1.84, SD = 0.49; violated PSPs with plausible relationships, M = 3.07, SD = 0.45; violated PSPs with implausible relationships, M = 1.72, SD = 0.42.

4. General discussion

In this study, we investigated whether the way in which PSPs are processed varies according to different memory demands and depends on the availability of the presupposed contextual information and the amount of resources available for PSP processing. We modulated contextual factors by (i) referring to a referent mentioned early or late in the context, existing or non-existing, in sentence set 1 (memory context) or (ii) inferring a referent in sentence set 2 that was more or less plausible due to semantic-pragmatic relations between an NP as PSP trigger and the context. We induced PSP processing in this sentence set by using the definite determiner, whose triggered reference processes should fail in any case, and by using the indefinite determiner, which should allow semantic-pragmatic inference depending on the context content (inference context). The two-sentence sets were presented in separate blocks in Experiment 1, whereas they were presented intermixed in Experiment 2 to avoid anticipation of the respective context. In sentence set 1 (memory context), the temporal distance of a potential context referent to the definite determiner in the test sentence influenced coherence judgments. Specifically, we observed that violated PSPs were judged to be more coherent when the potential referent was mentioned early in the context compared to a referent mentioned late in the context (Experiments 1 and 2). In Experiment 2, distance had an effect on both violated and intact PSPs. In sentence set 2 (inference context), no PSP consistency effect was observed, whereas the pragmatic-semantic fit of the test sentence NP exerted a very strong influence on coherence judgments independent of the presentation mode of sentence sets (blocked vs. intermixed).

The finding that coherence judgments depend on the temporal distance of a potential referent in the discourse (memory context) is noteworthy because it suggests that the reference process triggered by the definite determiner was modulated by the different temporal mention of the referent in the discourse. This finding may be explained in terms of increased memory demands for retrieving temporally distant information (e.g., Streb et al., Reference Streb, Hennighausen and Rösler2004), which may interfere with PSP reference processes. For example, some authors report that memory demands for referent integration increase when referring to relevant information mentioned early in the discourse (Gibson, Reference Gibson, Miyashita, Marantz and O’Neil2000; Warren, Reference Warren2001). Since increased cognitive demands occur generally when processing PSP vs. non-PSP sentence structures (e.g., Tiemann et al., Reference Tiemann, Schmid, Bade, Rolke, Hertrich, Ackermann, Knapp, Beck, Reich, Horch and Pauly2011) and when processing violated vs. intact PSP (e.g., Rolke et al., Reference Rolke, Kirsten, Seibold, Dietrich and Hertrich2023; Schneider et al., Reference Schneider, Bade and Janczik2020), an interaction could take place here in that more difficult memory retrieval leaves fewer resources for the PSP reference processes (e.g., Fiebach et al., Reference Fiebach, Schlesewsky and Friederici2002). This, in turn, could lead to the observed outcome of less clear recall of whether a potential referent was mentioned as negated and non-existent or as existent, and thus less clear classification of distant referents.

Interestingly, the results showed a more robust distance effect for negated referents (violated PSP consistency) than for non-negated referents (intact PSP consistency) in both Experiments. In our sentence material, the existence PSP was violated by negating the referential object in the context, whereas the existence PSP was intact by contextually introducing an indefinite NP as a referent (e.g., “…Tina has no/a suitcase. …. When Tina packs the suitcase, …”). As the violation of PSP consistency was realized by a negation in our study, processing negation might have contributed to our results. Dudschig et al. (Reference Dudschig, Kaup, Liu and Schwab2021a) suggest that more cognitive resources are required for processing a negation than for processing the non-negated opposition. They demonstrated this experimentally by testing the use of negation within directional instructions (e.g., “not left”, “now left”, “not right”, “now right”) in children, and the response to negative instructions was slower than to affirmative instructions (Dudschig et al., Reference Dudschig, Kaup, Svaldi and Gulewitsch2021b). The authors concluded that semantic understanding of negation requires inhibitory control processes in which the affirmation must first be represented and then inhibited. Thus, the retrieval of negated information, in addition to the already cognitively demanding processing of temporal distance, could strain the capacity of working memory, making its processing resources scarce for the retrieval and integration of the referent and explaining unclear coherence judgments, especially in the case of distant and violated PSP consistency.

One further possibility to explain the influence of the temporal distance of the referent from its trigger on the current coherence judgment would be a different way of representing the discourse elements in far and close contexts. Empirical evidence shows that in progressive reading or listening, the lexical or syntactic information mentioned in the text remains in memory only until the meaning content has been semantically interpreted and a long-term representation has been created (Jarvella, Reference Jarvella1971; Sachs, Reference Sachs1967). Van Dijk and Kintsch (Reference Van Dijk and Kintsch1983) summarized in their tripartite model that lexical input provides the basis for initial surface processing, which is only briefly retained in memory. In a subsequent stage of processing, propositions and concepts are formed, which contribute to a basic semantic understanding of the discourse content and are retained in memory. Finally, situational and individual experiences are linked to the discourse content (see also Sparks & Rapp, Reference Sparks and Rapp2010 for an overview). It is possible that concrete discourse information, e.g. whether a mentioned referent was present in the context or not, gets lost in the increasingly abstract and semantic discourse representation. Since this abstraction is presumably more advanced for distant information than for briefly mentioned content, the probability of losing concrete information is higher for distant content than for close content. Such a distant and more abstract representation would then contain less details when being accessed later, and this might impair the ability to judge discourse coherence. In addition to a possible change in representation mode, some authors suggest that contextual information that is mentioned late (e.g., O’Brien, Reference O’Brien1987), perceived as important (e.g., Cirilo, Reference Cirilo1981), or highly related (e.g., Burkhardt, Reference Burkhardt2007) is highlighted in its activation level, while the activation of other contextual information is suppressed (Kintsch & van Dijk, Reference Kintsch and van Dijk1978; van Dijk & Kintsch, Reference Van Dijk and Kintsch1983). To minimize memory load, early presented representations may be deactivated once a higher-level referential representation has been formed (Just & Carpenter, Reference Just and Carpenter1992). In the current sentence material, a referent mentioned early in the context would be lexically processed but would receive a lower level of activation, making it more difficult to recall and thus more difficult to judge coherence. Activation differences between distant and close possible referents of the discourse representation also provide a possible basis for explaining the more moderate consistency effect at longer discourse distances.

The results obtained for sentence set 2 (inference context) also provide some interesting new insights into discourse processing. The results of Experiment 1 (blocked presentation of the two sentence sets) and Experiment 2 (mixed presentation of the sentence sets) show that in the case of apparent semantic fit vs. non-fit, the semantic context is considered essential for coherence judgments, whereas PSP consistency seems to play no or only a very minor role. It was surprising to us that PSP fit had no effect because, according to previous findings (Rolke et al., Reference Rolke, Kirsten, Seibold, Dietrich and Hertrich2023), we would have expected the incorrect use of the definite determiner without a referent to be a strong violation of communication rules, which should lead to comprehension difficulties and thus to a judgment of lower coherence. However, Ferstl and von Cramon (Reference Ferstl and von Cramon2001) have already shown that general discourse comprehension or global discourse coherence processing was not impaired when cohesive ties, such as the pronoun ihr (‘her’), falsely suggested a relationship between sentences that did not exist. In sentence set 2, we can assume that an absent consideration of PSP consistency does not jeopardize global discourse comprehension and that PSP consistency seems to play a subordinate function in global discourse comprehension, while the semantic-pragmatic plausibility of the test sentence NP in relation to the context is in focus.

This idea is in line with several theoretical accounts of discourse processing. For instance, Sanford and Garrod (Reference Sanford and Garrod1989) have argued in their immediacy hypothesis that anaphora resolution need not be the key process in all discourse structures, but that other processes may take precedence and occur immediately. According to the authors, narrative discourse structures are characterized by a causal chain of events: Sequences of events lead to subsequent events and can be causally traced back to earlier sequences of events (Trabasso & van den Broek, Reference Trabasso and Van Den Broek1985; van den Broek, Reference Van den Broek, Balota, d’Arcais and Rayner1990) or can create expectations about subsequent discourse content and facilitate discourse comprehension (Zwaan & Rapp, Reference Zwaan, Rapp, Traxler and Gernsbacher2006). The discourse used in the present experiments had a narrative character: The action of a protagonist (e.g., “Simon goes hiking”) was described in an action space characterized by the presence or absence of objects (e.g., “a rope”, “no tent”). In the test sentence, which was introduced by a temporal adverb (“when”), another action of the same protagonist (“Simon”) took place with regard to an object that has already been mentioned (sentence set 1) or had not yet been mentioned (sentence set 2). Because of this narrative discourse structure, it is possible that for discourse understanding participants weighted certain discourse features, such as the semantic-pragmatic causality of events, more heavily than others, possibly saving cognitive resources for processing less weighted discourse features. Furthermore, according to Kintsch’s model of the construction and integration of verbal input (Kintsch, Reference Kintsch1988; Kintsch & van Dijk, Reference Kintsch and van Dijk1978), the semantic meaning of a constituent is activated in a construction phase, and its integration is pragmatically supported by the meaning of the context (Zwaan & Rapp, Reference Zwaan, Rapp, Traxler and Gernsbacher2006). In the construction phase, events are indexed and linked in memory along five dimensions: time, space, protagonist, causality, and intentionality (Zwaan et al., Reference Zwaan, Langston and Graesser1995). When events are combined, certain dimensions can be brought into focus (De Vega et al., Reference De Vega, Robertson, Glenberg, Kaschak and Rinck2004), while dimensions such as time and protagonist are observed independently of instructions (Therriault et al., Reference Therriault, Rinck and Zwaan2006). In sentence set 2, a new object appears that was not previously mentioned in the context, which expands the discourse space and is therefore indexed and combined as a new event. According to Zwaan and Rapp (Reference Zwaan, Rapp, Traxler and Gernsbacher2006), anaphoric resolution has no event-indexing relevance, but determines the way in which information must be integrated into a context. In this respect, our results show that anaphoric information might, in principle, modulate discourse coherence judgments (sentence set 1), but does not have to (sentence set 2), thus revealing the possibility of weighting event-indexing and -combining operations to construct a situational discourse model. Assuming that working memory capacity is limited, this weighting range could be explained by strategies to minimize memory load by focusing on the most prominent hint to establish a coherent discourse model.

The above conclusion assumes that the processing of PSPs depends on the context (i.e., the sentence sets) in which the PSPs are embedded. When comparing the two sentence sets, however, it is essential to consider an additional factor. The two-sentence sets differ not only concerning their context, but they additionally differ in terms of the PSP that is triggered in using the definite determiner in sentence set 1 (memory context) and using the definite and indefinite determiner in sentence set 2 (inference context). While in sentence set 1, the definite determiner contains a violation of the existence PSP via the negation of a potential referent, a violation of the existence PSP in sentence set 2 is given by the fact that a potential referent for the definite determiner has not been mentioned. The different results concerning the PSP consistency effect between the sentence sets could therefore also be explained by a differential degree of PSP violation. In this sense, the use of negated referents in the memory context is probably a stronger violation than in a neutral context in which the referent was simply not mentioned. In the latter case, it is possible to perceive the PSP violation rather as a small blur, accommodating the unmentioned referent as existing in an imagined contextual space, whereas it should be hard to accommodate an explicitly negated referent.

Various studies actually suggest that the same PSP trigger (here, the definite determiner) might contain different PSPs, which might be furthermore processed in a different manner. As described in the introduction, several studies (Domaneschi & Di Paola, Reference Domaneschi and Di Paola2018; Haviland & Clark, Reference Haviland and Clark1974; Kirsten et al., Reference Kirsten, Tiemann, Seibold, Hertrich, Beck and Rolke2014; Schneider et al., Reference Schneider, Bade and Janczik2020) show that processing an unfulfilled PSP triggered by the definite determiner comes along with enhanced processing costs and with lowered ratings for coherence (see Rolke et al., Reference Rolke, Kirsten, Seibold, Dietrich and Hertrich2023). These enhanced processing costs occur irrespective of whether the context lacks an adequate referent for the definite determiner (Clifton, Reference Clifton2013; Garnham et al., Reference Garnham, Oakhill and Cain1997) or whether the context is ambiguous, thereby impeding the smooth performance of the reference process (see, e.g., Altmann & Steedman, Reference Altmann and Steedman1988). Moreover, Rolke et al. (Reference Rolke, Kirsten, Seibold, Dietrich and Hertrich2023) report that, depending on the context of the subsequent sentence, unfulfilled PSPs triggered by the definite determiner can either immediately result in a slowdown in reading-time or cause possible reference processes to be postponed to a later point in the sentence. The authors assumed that the way a reference process is solved might depend on the actual context in which the trigger occurred and on the potential of the context to supplement absent information. Rolke et al. (Reference Rolke, Kirsten, Seibold, Dietrich and Hertrich2023) conceptualized this potential accommodation process as occurring at the end of a cognitive PSP processing sequence. Given that the present study solicited assessments of coherence, it is probable that such accommodation processes occurred prior to the evaluation, and this in turn would explain the absence of a PSP consistency effect in sentence set 2.

In addition to other studies, the present study shows that PSP processing is not an all-or-nothing process that always takes place to the same extent and in a stereotypical manner. On the contrary, we show that depending on the memory load and the global context, the specific PSP violation is perceived differently by the cognitive system and violations might possibly be accommodated. Given the finding that working memory load affects PSP processing, future research could examine how individual differences in discourse processing strategies correlate with variations in working memory capacity. Furthermore, our results suggest that accommodation is likely related to coherence judgments. This opens new avenues for investigating the underlying mechanisms of coherence judgments and their interaction with accommodation. For example, examining brain activation patterns during coherence judgment tasks associated with the accommodation process could shed light on the cognitive processes involved and provide valuable insights and possibly identify neurophysiological markers that signal when accommodation is occurring. Finally, based on the findings by Carter and Nieuwland (Reference Carter and Nieuwland2022), who observed ERP evidence for expectation-based modulation of reference processes for the definite and the indefinite determiner, it would be interesting to see whether these expectancy-based processes might be triggered by different discourse contexts or by knowledge of communication partners, which in turn might influence reference processing and accommodation behavior.