R-3 Repository :: Browsing by Author "Martin, Randi"

Browsing by Author "Martin, Randi"

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Brain Modularity Mediates the Relation between Task Complexity and Performance
(The MIT Press, 2017) Yue, Qiuhai; Martin, Randi; Fischer-Baum, Simon; Ramos-Nuñez, Aurora I.; Ye, Fengdan; Deem, Michael W.; Center for Theoretical Biological Physics
Recent work in cognitive neuroscience has focused on analyzing the brain as a network, rather than as a collection of independent regions. Prior studies taking this approach have found that individual differences in the degree of modularity of the brain network relate to performance on cognitive tasks. However, inconsistent results concerning the direction of this relationship have been obtained, with some tasks showing better performance as modularity increases and other tasks showing worse performance. A recent theoretical model [Chen, M., & Deem, M. W. 2015. Development of modularity in the neural activity of children's brains. Physical Biology, 12, 016009] suggests that these inconsistencies may be explained on the grounds that high-modularity networks favor performance on simple tasks whereas low-modularity networks favor performance on more complex tasks. The current study tests these predictions by relating modularity from resting-state fMRI to performance on a set of simple and complex behavioral tasks. Complex and simple tasks were defined on the basis of whether they did or did not draw on executive attention. Consistent with predictions, we found a negative correlation between individuals' modularity and their performance on a composite measure combining scores from the complex tasks but a positive correlation with performance on a composite measure combining scores from the simple tasks. These results and theory presented here provide a framework for linking measures of whole-brain organization from network neuroscience to cognitive processing.
Evaluating the relationship between sublexical and lexical processing in speech perception: Evidence from aphasia
(Elsevier, 2017) Dial, Heather; Martin, Randi
Several studies have reported that aphasic patients may perform substantially better on lexical than sublexical perception tasks (e.g., Miceli et al., 1980). These findings challenge claims made by models of speech perception which assume obligatory sublexical processing (e.g., McClelland and Elman, 1986; Norris, 1994). However, prior studies have not closely matched the phonological similarity of targets and distractors or task demands of the sublexical and lexical perception tasks. The current study addressed shortcomings of these prior studies, testing 13 aphasic patients on sublexical and lexical tasks matched in phonological similarity of stimuli and task demands. When the lexical and sublexical tasks were not matched (Experiment 1a), as in prior studies (e.g., Miceli et al., 1980), several patients with impaired sublexical perception were within the control range on tasks tapping lexical perception. In contrast, when the lexical and sublexical tasks (sublexical: syllable discrimination, auditory-written syllable matching (AWSM); lexical: word discrimination, lexical decision, and picture-word matching (PWM)) were matched on these factors (Experiments 1b and 2), in most instances, patients were impaired on both sublexical and lexical tasks relative to controls and performance on the lexical tasks was not significantly greater than that on the sublexical tasks. For two patients, performance on one lexical task was statistically better than that on one sublexical task, but the advantage was not replicated across other task comparisons. The current study is consistent with models of speech perception which assume obligatory sublexical processing and fails to support models that do not require successful sublexical perception in order to access lexical levels (e.g., Goldinger, 1998; Hickok and Poeppel, 2000).
Language Production and Working Memory Abilities in Healthy Younger and Older Adults
(2024-04-16) Zahn, Rachel; Martin, Randi
Evidence from neuropsychological studies of individuals with brain damage post-stroke has supported the separation of working memory (WM) capacities for semantic (word meaning) and phonological (speech sound) information. These separate capacities have been shown to play different roles in supporting multiword language production, with semantic WM being particularly critical for the fluent production of multiword speech. The current study investigated the role that age-related declines in phonological and semantic WM play in language production. Using spontaneous production tasks and eye tracking during constrained sentence production, I investigated the characteristics of healthy young and older adults’ speech and speech planning processes and their relation to WM. These two methods provided converging evidence for the role of semantic WM in planning multiple content words during language production. In older adults’ narrative production, higher semantic WM capacity was associated with more elaborative speech. In sentence production with eye tracking, young adults with greater semantic WM capacity showed a greater tendency to look to a second noun in an initial phrase before speech onset, suggesting that they were planning both nouns before speaking and that this planning required semantic WM. The fact that older adults showed semantic WM effects in narrative production and young adults only showed effects in the eye gaze data highlights the advantage of combining eye gaze data with more standard behavioral measures in investigating the cognitive processes occurring before speech onset.
Relationship between Verbal Working Memory and Prediction Performance in Sentence Processing
(2024-06-17) Lu, Yu; Martin, Randi; Fischer-Baum, Simon
Extensive research has shown converging evidence for prediction in the context of sentence comprehension tasks. While there is little debate that predictive processing is happening during language comprehension, precisely how we are able to generate these predictions is relatively unknown. The current project explores the cognitive factors supporting accurate prediction performance, focusing on the role of verbal working memory. The project takes a case study approach, examining the ability to predict upcoming words in individuals with different types of verbal working deficits following brain damage. Evidence from brain damaged individuals has shown that verbal WM can be divided into separable semantic and phonological WM systems which can be separably damaged. Four aphasic individuals were recruited as participants, one with phonological WM deficit (TP), two with semantic WM deficit (WC, DW), and one with both a phonological and semantic deficit (KA). We hypothesized that semantic WM, but not phonological WM, is related to the ability to make predictions during a language processing task. Experiment 1 compared the aphasic participants’ the prediction performance measured through a sentence completion task to a group of control older adults. All 4 participants showed worse prediction performance than controls, suggesting both phonological and semantic WM are important for accurate prediction, contra our prediction. However, it is possible that deficits in the speed with which language can be processed also contributes to the ability to predict particular for those individuals with phonological WM deficits. Experiment 2 explored this possibility by slowing down the audio presentation rate in the sentence completion task with the same four brain-damaged participants. However, no clear effect of presentation rate on prediction performance was observed. What these results mean for the role of different kinds of verbal working memory in prediction will be discussed.
Semantic priming effects in a patient with a semantic short-term memory deficit
(2008) Hong, An; Martin, Randi
Some researchers have argued that short-term memory (STM) deficits are due to overly rapid loss of activation of the nodes in the lexical-semantic system. The current study investigated the activation and decay of semantic representations for a patient (ML) with a semantic STM deficit using a semantic priming paradigm. Experiment 1 used a traditional paired presentation task to examine priming at two SOAs (350ms & 900ms). Experiment 2 and 3 used a single presentation task to reduce the use of strategies at long SOAs. ML demonstrated normal priming effects at short and long SOAs when priming primarily reflected automatic spreading activation. The results suggest that ML has normal activation and decay in the lexical-semantic system and support a model with STM buffers separate from the lexical-semantic system. Experiment 4 explored ML and older control subjects' use of strategies in a priming task. The sources of ML's STM deficit were discussed.
Sentence processing in aphasic speakers with short-term memory deficits: Interactions between structural and lexical processing
(2017-08-10) Yan, Hao; Martin, Randi
The current research investigates interactions between lexical and structural processing in the construction and interpretation of transitive and dative sentence structures, and relates speakers’ choice of structure in sentence production to STM processes and recent/long-term language experience conditioned on lexical information. Study 1 investigated whether STM is related to the increased tendency for speakers to reuse a structure when the verb is also repeated. Speakers show syntactic priming – that is, a tendency to repeat syntactic constructions they have recently comprehended or produced – and this tendency is even stronger when adjacent utterances share the same main verb, termed the lexical boost. Some have suggested that abstract syntactic priming (i.e., with no lexical overlap) derives from implicit learning, whereas the lexical boost derives from explicit short-term memory (STM) for the prime (e.g., Chang, Dell, & Bock, 2006). To address this issue, Experiment 1.1 assessed twelve aphasic patients with varying degrees of STM deficits and eleven age-matched healthy control speakers in a syntactic priming experiment using a picture description paradigm. Experiment 1.2 assessed eight patients and ten control speakers in another syntactic priming task using written word arrays for target trials. Despite patients’ difficulty in maintaining phonological, semantic, and structural information, as evidenced by various STM and sentence repetition measures, most of them showed lexical boost effects comparable to those of healthy speakers. Moreover, the size of the lexical boost was unrelated to the degree of STM deficit, suggesting that the lexical boost does not rely on explicit memory. Alternative explanations for the differing patterns for syntactic priming with and without lexical overlap are discussed. Compared to young speakers, many patients and some older control speakers had very limited production of double object (DO) dative sentences in the picture description task in Experiment 1.1 and predominantly produced prepositional dative (PD) sentences. Study 2 included four experiments to explore factors behind the choice of structure in dative sentence production. There are various possible accounts of speakers’ preference for the PD structure over the DO structure. DO could be syntactically more complex (Chomsky, 1975; Beck & Johnson, 2004), or more difficult to parse without explicit markers of grammatical/thematic roles of post-verbal nouns (Stowell, 1981). The word order in DO could be different from a default order of conceptual planning, which plans the verb and the theme together, before a recipient (O’Grady & Lee, 2005). Accessibility of nouns after the verb may also affect word order and the choice of structure in dative sentence production (Bresnan, Cueni, Nikitina, & Baayen, 2007). In accordance with these hypotheses, the factors investigated included syntactic complexity (DO vs. PD), function word processing (functions of prepositions in dative sentences), semantic factors (ease of semantic integration between the verb and the theme), processing factors (accessibility of the recipient), as well as the relation between these factors and STM capacities. In a sentence repetition task, Study 2.1a found that DO sentences were more difficult to repeat than PD sentences for patients, and this structural effect was related to percent DO production in Experiment 1.1. Pronoun recipients facilitated repetition of DO sentences, and easy semantic integration between the verb and the theme improved repetition of PD sentences. A grammaticality judgment task in Study 2.1b found some evidence for a weak pronoun recipient effect, but not a semantic integration effect. Only a small structural effect was found, which was not related to percent DO production in Experiment 1.1, suggesting that the limited DO production was not caused by any potential weakness in the syntactic knowledge of the DO structure. Study 2.1c found limited evidence for a structural effect in a sentence anomaly judgment task, and some evidence that prepositions in PD sentences and provide-with sentences serve as explicit markers of grammatical functions to facilitate parsing of post-verbal objects. Finally, Study 2.2 found that both patient and control speakers were more likely to choose the DO structure in picture description when using pronoun recipients or more accessible full NP recipients, reflecting a tendency to produce the more accessible word earlier in a sentence. This accessibility effect and the pronoun recipient in Experiment 2.1a and 2.2 were consistent with findings in corpus studies that a DO structure with a pronoun recipient is a highly frequent dative construction (Bresnan, Cueni, Nikitina, & Baayen, 2007), suggesting an important role of language experience in sentence processing. Importantly, STM capacities were related to percent DO production in Experiments 1.1, 1.2, and 2.2, and the structural effect in dative sentence repetition in Experiment 2.1a, indicating that the processing difficulty with DO sentences is related to STM costs. Taken together, these findings in Study 1 and 2 support a multi-factorial, usage-based account of sentence processing (Gahl & Menn, 2016; Menn & Bastiaanse, 2016), which is achieved via the interactions between structural processing and lexical processing, with the potential support of STM resources for some aspects of these processes.
The Role of Phonological Working Memory in Narrative Production: Evidence from Chronic Aphasia
(2021-05-10) Zahn, Rachel; Martin, Randi
Previous work has supported a critical role for semantic, but not phonological, working memory (WM) in the ability to produce multiword utterances. In narrative production of patients at the acute stage of stroke it was shown that correlations between semantic, but not phonological WM, and narrative measures of elaboration remained when single word production abilities were included in the model. However, the acute stroke results also revealed relations between phonological WM and narrative production – specifically, a positive relationship between digit matching span (a phonological WM measure) and words per minute, and a negative relationship between digit matching span and proportion pronouns relative to nouns. Two hypotheses have been compared to explain these relationships. The first is that both digit matching span and these narrative measures relate to the speed and ease of phonological retrieval. The second is that there are separate input and output phonological WM buffers, and the output buffer plays a key role in fluent speech and phonological WM. In a sample of participants at the chronic stage of stroke two approaches, a case series and a case study approach, were used to address these two hypotheses. The case series approach showed evidence that single word retrieval abilities predicted words per minute above changes in output phonological WM, supporting the phonological retrieval hypothesis. However, the results for proportion pronouns differed between the acute and chronic stages, most likely due to different sources of variation in pronoun use for the two groups. The case series approach showed evidence for the distinction of input and output phonological WM buffers. Implications from the two approaches will be discussed.
Understanding the Conditions for Detecting a Phonology to Articulation Cascade in Speech Production
(2023-08-11) Irons, Sarah T; Fischer-Baum, Simon; Martin, Randi; Niedzielski, Nancy
Phonetic distortions, subtle acoustic traces of how a competitor would be produced on the articulation of a response, have been used as evidence for cascading activation from phonological planning to articulatory implementation, that is that information flows between these levels of representation in the language production system prior to selection at the phonological planning level. Phonetic distortions are a robust finding, when focusing on speech errors, produced either in tongue twisters (Baese-Berk & Goldrick, 2009; Frisch & Wright, 2002; Goldrick, 2016; Goldrick & Blumstein, 2006; Goldrick et al., 2016; Goldstein et al., 2007; McMillan & Corley, 2010; Pouplier, 2007) or in naturalistic speech (Alderete et al., 2021). However, a recent study failed to find evidence for phonetic distortions in another context in which it would be expected, single word reading aloud of irregular words in which the lexical and sublexical routes generate phonological plans for different vowels (Irons, 2020). The goal of this dissertation is to understand why this discrepancy exists, that is why phonetic distortions are observed in some, but not all cases, in which they are predicted by cascading activation theories of speech production as there are many, potentially critical differences between the paradigms that do and do not observe phonetic distortions. In this dissertation, I present two experiments, one using tongue twisters, and one using picture-word interference, designed specifically to control for differences in errors, scope of planning and word position, to allow us to better understand when a cascade from phonological planning to articulatory implementation can be observed phonetically. Similar to past tongue twister work (Baese-Berk & Goldrick, 2009; Frisch & Wright, 2002; Goldrick, 2016; Goldrick & Blumstein, 2006; Goldrick et al., 2016; Goldstein et al., 2007; McMillan & Corley, 2010; Pouplier, 2007) I observed phonetic distortions, evidence for cascading activation in onset tongue twisters. In nucleus tongue twisters I found that cascading activation might present differently in vowels than it does in consonants. We did not, however, observe phonetic distortions in picture-word interference, therefore open questions remain about how scope of planning and error effects may be responsible for phonetic distortion evidence for cascading activation.

Browsing by Author "Martin, Randi"

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