Memory for linguistic features and the focus of attention: evidence from the dynamics of agreement inside DP.

The amount of information that can be concurrently maintained in the focus of attention is strongly restricted (Broadbent, 1958). The goal of this study was to test whether this restriction was functionally significant for language comprehension. We examined the time course dynamics of processing determiner-head agreement in English demonstrative phrases. We found evidence that agreement processing was slowed when determiner and head were no longer adjacent, but separated by modifiers. We argue that some information is shunted nearly immediately from the focus of attention, necessitating its later retrieval. Plural, the marked feature value for number, exhibits better preservation in the focus of attention, however, than the unmarked value, singular.

Hierarchical structure and memory mechanisms in agreement attraction.

Speakers occasionally produce verbs that agree with an element that is not the subject, a so-called 'attractor'; likewise, comprehenders occasionally fail to notice agreement errors when the verb agrees with the attractor. Cross-linguistic studies converge in showing that attraction is modulated by the hierarchical position of the attractor in the sentence structure. We report two experiments exploring the link between structural position and memory representations in attraction. The method used is innovative in two respects: we used jabberwocky materials to control for semantic influences and focus on structural agreement processing, and we used a Speed-Accuracy Trade-off (SAT) design combined with a memory probe recognition task, as classically used in list memorization tasks. SAT enabled the joint measurement of retrieval speed and retrieval accuracy of subjects and attractors in sentences that typically elicit attraction errors. Experiment 1 first established that attraction arises in jabberwocky sentences, to a similar extent and showing structure-dependency effects, as in natural sentences. Experiment 2 showed a close alignment between the attraction profiles found in Experiment 1 and memory parameters. Results support a content-addressable architecture of memory representations for sentences in which nouns' accessibility depends on their syntactic position, while subjects are kept in the focus of attention.

The Predictive Value of Tagalog Voice Morphology in Filler-Gap Dependency Formation.

Research has shown that when processing filler-gap dependencies, comprehenders do not wait until they encounter all of the bottom-up information in the input. Instead, they use various types of linguistic information to predictively posit a gap that would allow the dependency to be resolved. They can use syntactic (Traxler and Pickering, 1996), lexical (Trueswell et al., 1994), morphological (Kamide et al., 2003), and prosodic (Nagel et al., 1994) information. Here we examine whether Tagalog comprehenders use the language's voice morphology to guide their incremental interpretations. We hypothesized that voice allows comprehenders to commit to an interpretation upon encountering the verb, since they have information about the event structure at this point in time and by virtue of the voice morphology, the thematic role of the filler. In experiment 1, using an acceptability judgment study, we found that comprehenders differed in how they used the different voices in different filler-gap contexts to detect the licitness of displacements. These differences may have consequences for how voice is used in real-time. In experiments 2 and 3, using the stops-making-sense paradigm (Boland et al., 1990), we found that comprehenders used voice as a cue to actively associate the filler with the gap. However, in experiment 3, the way in which they used voice varied by type and varied across types of filler-gap dependencies. We argue that comprehenders were using construction-specific cue validities when processing filler-gap dependencies. However, they also engaged with other classes of linguistic information, including (but not limited to) information about the structural similarities and the thematic complexity of the dependencies involved, and the relative frequency of the different types of voices in the language. These interactions resulted in processing asymmetries.

A new argument for co-active parses during language comprehension.

One perennially important question for theories of sentence comprehension is whether the human sentence processing mechanism is parallel (i.e., it simultaneously represents multiple syntactic analyses of linguistic input) or serial (i.e., it constructs only a single analysis at a time). Despite its centrality, this question has proven difficult to address for both theoretical and methodological reasons (Gibson & Pearlmutter, 2000; Lewis, 2000). In the present study, we reassess this question from a novel perspective. We investigated the well-known ambiguity advantage effect (Traxler, Pickering, & Clifton, 1998) in a speeded acceptability judgment task. We adopted a signal detection theoretic approach to these data, with the goal of determining whether speeded judgment responses were conditioned on one or multiple syntactic analyses. To link these results to incremental parsing models, we developed formal models to quantitatively evaluate how serial and parallel parsing models should impact perceived sentence acceptability in our task. Our results suggest that speeded acceptability judgments are jointly conditioned on multiple parses of the input, a finding that is overall more consistent with parallel parsing models than serial models. Our study thus provides a new, psychophysical argument for coactive parses during language comprehension. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Developing incrementality in filler-gap dependency processing.

Much work has demonstrated that children are able to use bottom-up linguistic cues to incrementally interpret sentences, but there is little understanding of the extent to which children's comprehension mechanisms are guided by top-down linguistic information that can be learned from distributional regularities in the input. Using a visual world eye tracking experiment and a corpus analysis, the current study investigates whether 5- and 6-year-old children incrementally assign interpretations to temporarily ambiguous wh-questions like What was Emily eating the cake with __? In the visual world eye-tracking experiment, adults demonstrated evidence for active dependency formation at the earliest region (i.e., the verb region), while 6-year-old children demonstrated a spill-over effect of this bias in the subsequent NP region. No evidence for this bias was found in 5-year-olds, although the speed of arrival at the ultimately correct instrument interpretation appears to be modulated by the vocabulary size. These results suggest that adult-like active formation of filler-gap dependencies begins to emerge around age 6. The corpus analysis of filler-gap dependency structures in adult corpora and child corpora demonstrate that the distributional regularities in either corpora are equally in favor of early, incremental completion of filler-gap dependencies, suggesting that the distributional information in the input is either not relevant to this incremental bias, or that 5-year-old children are somehow unable to recruit this information in real-time comprehension. Taken together, these findings shed light on the origin of the incremental processing bias in filler-gap dependency processing, as well as on the role of language experience and cognitive constraints in the development of incremental sentence processing mechanisms.

Grammatical licensing and relative clause parsing in a flexible word-order language.

Evidence from two experiments reveals that in Chamorro, a verb-first language, the comprehension of relative clauses (RCs) is sensitive to the order of the RC with respect to the head. Unlike most other languages, Chamorro allows both postnominal and prenominal RCs, so it is possible to compare how the two types are processed within the same language. Moreover, Chamorro is a small language whose speakers do not fit the typical profile of participants in cognitive science experiments. We found that RC comprehension is affected by the relative order of RC and head, and by other language-specific factors. However, we also found new support for a subject gap advantage in all RC types. This advantage emerged in early response measures and was reinforced in postnominal RCs, but often outcompeted in prenominal RCs by other pressures. We frame this competition in terms of a model in which grammatical licensing requirements play a key role in comprehension.

The structure-sensitivity of memory access: evidence from Mandarin Chinese.

The present study examined the processing of the Mandarin Chinese long-distance reflexive ziji to evaluate the role that syntactic structure plays in the memory retrieval operations that support sentence comprehension. Using the multiple-response speed-accuracy tradeoff (MR-SAT) paradigm, we measured the speed with which comprehenders retrieve an antecedent for ziji. Our experimental materials contrasted sentences where ziji's antecedent was in the local clause with sentences where ziji's antecedent was in a distant clause. Time course results from MR-SAT suggest that ziji dependencies with syntactically distant antecedents are slower to process than syntactically local dependencies. To aid in interpreting the SAT data, we present a formal model of the antecedent retrieval process, and derive quantitative predictions about the time course of antecedent retrieval. The modeling results support the Local Search hypothesis: during syntactic retrieval, comprehenders initially limit memory search to the local syntactic domain. We argue that Local Search hypothesis has important implications for theories of locality effects in sentence comprehension. In particular, our results suggest that not all locality effects may be reduced to the effects of temporal decay and retrieval interference.

Going the distance: Memory and control processes in active dependency construction.

Filler-gap dependencies make strong demands on working memory in language comprehension because they cannot always be immediately resolved. In a series of three reading-time studies, we test the idea that these demands can be decomposed into active maintenance processes and retrieval events. Results indicate that the fact that a displaced phrase exists and the identity of its basic syntactic category both immediately impact comprehension at potential gap sites. In contrast, specific lexical details of the displaced phrase show an immediate effect only for short dependencies and a much later effect for longer dependencies. We argue that coarse-grained information about the filler is actively maintained and is used to make phrase structure parsing decisions, whereas finer grained information is more quickly released from active maintenance and consequently has to be retrieved at the gap site.

Functional trade-offs in white matter axonal scaling.

The brains of large mammals have lower rates of metabolism than those of small mammals, but the functional consequences of this scaling are not well understood. An attractive target for analysis is axons, whose size, speed and energy consumption are straightforwardly related. Here we show that from shrews to whales, the composition of white matter shifts from compact, slow-conducting, and energetically expensive unmyelinated axons to large, fast-conducting, and energetically inexpensive myelinated axons. The fastest axons have conduction times of 1-5 ms across the neocortex and <1 ms from the eye to the brain, suggesting that in select sets of communicating fibers, large brains reduce transmission delays and metabolic firing costs at the expense of increased volume. Delays and potential imprecision in cross-brain conduction times are especially great in unmyelinated axons, which may transmit information via firing rate rather than precise spike timing. In neocortex, axon size distributions can account for the scaling of per-volume metabolic rate and suggest a maximum supportable firing rate, averaged across all axons, of 7 +/- 2 Hz. Axon size distributions also account for the scaling of white matter volume with respect to brain size. The heterogeneous white matter composition found in large brains thus reflects a metabolically constrained trade-off that reduces both volume and conduction time.