R-3 Repository :: Browsing by Author "Schnur, Tatiana T."

Browsing by Author "Schnur, Tatiana T."

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All cumulative semantic interference is not equal: A test of the Dark Side Model of lexical access
(2013-09-16) Walker Hughes, Julie; Schnur, Tatiana T.; Martin, Randi C.; Fischer-Baum, Simon
Language production depends upon the context in which words are named. Renaming previous items results in facilitation while naming pictures semantically related to previous items causes interference. A computational model (Oppenheim, Dell, & Schwartz, 2010) proposes that both facilitation and interference are the result of using naming events as “learning experiences” to ensure future accuracy. The model successfully simulates naming data from different semantic interference paradigms by implementing a learning mechanism that creates interference and a boosting mechanism that resolves interference. This study tested this model’s assumptions that semantic interference effects in naming are created by learning and resolved by boosting. Findings revealed no relationship between individual performance across semantic interference tasks, and measured learning and boosting abilities did not predict performance. These results suggest that learning and boosting mechanisms do not fully characterize the processes underlying semantic interference when naming.
An investigation of audiovisual speech perception using the McGurk effect
(2014-04-14) Basu Mallick, Debshila; Beauchamp, Michael S.; Dannemiller, James L.; Beier, Margaret E.; Schnur, Tatiana T.
Integrating information from the auditory and visual modalities is vital for speech perception. In this thesis, I describe two studies of audiovisual speech perception that make use of an audiovisual illusion known as the McGurk effect. In the McGurk effect, two different syllables presented simultaneously in auditory and visual modalities are fused and perceived as a novel syllable (McGurk & MacDonald, 1976). In the first study, we conducted a large-scale assessment of the McGurk effect across fourteen McGurk stimuli tested in up to 165 participants. This study revealed that McGurk perception is characterized by wide variability across stimuli. The second study investigated whether phonetic identification training could increase McGurk perception. This study showed that participants improved on the training task, but there was no increase in McGurk perception.
Distinct loci of lexical and semantic access deficits in aphasia: Evidence from voxel-based lesion-symptom mapping and diffusion tensor imaging
(Elsevier, 2015) Harvey, Denise Y.; Schnur, Tatiana T.
Naming pictures and matching words to pictures belonging to the same semantic category negatively affects language production and comprehension. By most accounts, semantic interference arises when accessing lexical representations in naming (e.g., Damian, Vigliocco, & Levelt, 2001) and semantic representations in comprehension (e.g., Forde & Humphreys, 1997). Further, damage to the left inferior frontal gyrus (LIFG), a region implicated in cognitive control, results in increasing semantic interference when items repeat across cycles in both language production and comprehension (Jefferies, Baker, Doran, & Lambon Ralph, 2007). This generates the prediction that the LIFG via white matter connections supports resolution of semantic interference arising from different loci (lexical vsﾠsemantic) in the temporal lobe. However, it remains unclear whether the cognitive and neural mechanisms that resolve semantic interference are the same across tasks. Thus, we examined which gray matter structures [using whole brain and region of interest (ROI) approaches] and white matter connections (using deterministic tractography) when damaged impact semantic interference and its increase across cycles when repeatedly producing and understanding words in 15 speakers with varying lexical-semantic deficits from left hemisphere stroke. We found that damage to distinct brain regions, the posterior versusﾠanterior temporal lobe, was associated with semantic interference (collapsed across cycles) in naming and comprehension, respectively. Further, those with LIFG damage compared to those without exhibited marginally larger increases in semantic interference across cycles in naming but not comprehension. Lastly, the inferior fronto-occipital fasciculus, connecting the LIFG with posterior temporal lobe, related to semantic interference in naming, whereas the inferior longitudinal fasciculus (ILF), connecting posterior with anterior temporal regions related to semantic interference in comprehension. These neuroanatomical-behavioral findings have implications for models of the lexical-semantic language network by demonstrating that semantic interference in language production and comprehension involves different representations which differentially recruit a cognitive control mechanism for interference resolution.
Inhibitory control mechanisms and their role in task switching: A multi-methodological approach
(2013-05-13) Allen, Corinne; Martin, Randi C.; Schnur, Tatiana T.; Oswald, Frederick L.; Kemmer, Suzanne E.; Basak, Chandramallika
Executive control allows us to ignore distraction and switch between tasks in a flexible, yet organized fashion. While a hallmark of controlled behavior, distinctions among executive control processes are not thoroughly agreed upon. The present work explored the organization of two of these executive control processes, inhibition and shifting, and their relationship to each other. There were two primary goals. The first goal was to investigate the distinction among inhibitory control processes, as “inhibition” has oftentimes been considered a unitary construct. For example, there is evidence that response-distractor inhibition, which involves resolving interference from dominant responses or distractors in the external environment, is different from resistance to proactive interference (PI), which involves overcoming interference from previously relevant representations in memory. Using aging, neuropsychology, and individual differences methodologies, I investigated the unity and diversity of inhibitory control mechanisms. The healthy aging and neuropsychological evidence supported a distinction between response-distractor inhibition and resistance to proactive interference. However, when controlling for processing speed, the individual differences work suggested a need for further specification, as only a subset of these tasks emerged in the single factor model that provided the best fit to the data. The second goal was to explore how inhibitory control processes interact with task switching, as some theoretical accounts of task switching have suggested that switch costs result from the need to overcome interference from the previously relevant task. Inconsistent with these theories, I found little relation between inhibitory control and measures of global and local task switching, and instead, working memory served as the best predictor of these shifting measures. In contrast, inhibitory control was related to the backward inhibition abilities of older adults. These findings are discussed within a theory of working memory that accounts for the patterns of results found across the different methodologies.
Localizing Interference during Naming: Convergent Neuroimaging and Neuropsychological Evidence for the Function of Broca's Area
(National Academy of Science, 2009) Schnur, Tatiana T.; Schwartz, Myrna F.; Kimberg, Daniel Y.; Hirshorn, Elizabeth; Coslett, H. Branch; Thompson-Schill, Sharon L.
In order to produce a word, the intended word must be selected from a competing set of other words. In other domains where competition affects the selection process, the left inferior frontal gyrus (LIFG) responds to competition among incompatible representations. The aim of this study was to test whether the LIFG is necessary for resolution of competition in word production. Using a novel methodological approach applying the same rigorous analytic methods to neuropsychological data as is done with neuroimaging data, we compared brain activation patterns in normal speakers (using fMRI) with the results of lesion-deficit correlations in aphasic speakers who performed the same word production task designed to elicit competition during lexical selection. The degree of activation of the LIFG in normal speakers and damage to the LIFG in aphasic speakers was associated with performance on the production task. These convergent findings provide strong support for the hypothesis that the region of cortex commonly known as Broca's area (i.e., the posterior LIFG) serves to bias competitive interactions during language production.
Naming “CAT” in the Past Affects Naming “DOG” in the Present: How and Where Semantic Facilitation and Interference Occur
(2016-07-25) Wei, Tao; Schnur, Tatiana T.
Our speech is affected by recent naming experience (i.e., what we have said before). For example, after talking about your cat with friends, you may mistakenly say “cat” when you intended to say “dog”. Although the influence of naming experience on speech production has been known for a long time, it is unclear how naming experience shapes the language system and thus affects future speech. Specifically, whereas some studies find that naming semantically related pictures speeds up subsequent naming, recent studies demonstrate that previously naming semantically related pictures slows down future naming. Because these studies use various paradigms with different materials and experimental parameters to investigate how past naming influences future naming, it is difficult to explain how the same naming experience results in opposite effects (i.e., facilitation and interference). The goal of this dissertation is to bridge the gap between these contrasting results and determine how the language system is changed by past naming experience. To accomplish this goal, I tested both semantic facilitation and interference in naming within the same paradigm. In Experiment 1, by manipulating the interval between two naming events, I established the opposite effects caused by semantically related naming experience, suggesting that naming experience has two temporally distinct effects on subsequent speech production, short-lived facilitation and long-lasting interference. In Experiments 2 and 3, following previous methodology while simultaneously addressing its limitations, I investigated the cognitive locus of semantic facilitation and interference respectively. Results suggest a role of semantic processing in both facilitation and interference. Lastly, to provide further and convergent evidence about the locus (semantic vs. lexical) of semantic facilitation and interference in naming, I used fMRI in Experiment 4 to explore the neural loci of these two effects in the same picture naming experiment with one group of participants. The results suggest that facilitation has a semantic locus, while interference has loci at both semantic and lexical levels of processing. Together, these experiments systematically investigated the mechanisms and loci of facilitation and interference caused by past naming experience from both behavioral and neural perspectives. This work sheds light on the dynamic nature of the language system providing insight into how our past experiences shape our current cognitive processes/abilities.
The neural correlates of verb and noun processing A PET study
(1999) Perani, Daniela; Cappa, Stefano F.; Schnur, Tatiana T.; Tettamanti, Marco; Collina, Simona; Rosa, Mario Miguel; Fazio, Ferruccio; CNR; Oxford University Press
The hypothesis that categorical information, distinguishing among word classes, such as nouns, verbs, etc., is an organizational principle of lexical knowledge in the brain, is supported by the observation of aphasic subjects who are selectively impaired in the processing of nouns and verbs. The study lesion location in these patients has suggested that the left temporal lobe plays a crucial role in processing nouns, while the left frontal lobe is necessary for verbs. To delineate the brain areas involved in the processing of different word classes, we used PET to measure regional cerebral activity during tasks requiring reading of concrete and abstract nouns and verbs for lexical decision. These tasks activated an extensive network of brain areas, mostly in the left frontal and temporal cortex, which represents the neural correlate of single word processing. Some left hemispheric areas, including the dorsolateral frontal and lateral temporal cortex, were activated only by verbs, while there were no brain areas more active in response to nouns. Furthermore, the comparison of abstract and concrete words indicated that abstract word processing was associated with selective activations (right temporal pole and amygdala, bilateral inferior frontal cortex), while no brain areas were more active in response to concrete words. There were no significant interaction effects between word class and concreteness. Taken together, these findings are compatible with the view that lexical-semantic processing of words is mediated by an extensive, predominantly left hemispheric network of brain structures. Additional brain activations appear to be related to specific semantic content, or, in the case of verbs, may be associated with the automatic access of syntactic information.
Phonological planning during sentence production: beyond the verb
(Frontiers Media S.A., 2011-11) Schnur, Tatiana T.
The current study addresses the extent of phonological planning during spontaneous sentence production. Previous work shows that at articulation, phonological encoding occurs for entire phrases, but encoding beyond the initial phrase may be due to the syntactic relevance of the verb in planning the utterance. I conducted three experiments to investigate whether phonological planning crosses multiple grammatical phrase boundaries (as defined by the number of lexical heads of phrase) within a single phonological phrase. Using the picture–word interference paradigm, I found in two separate experiments a significant phonological facilitation effect to both the verb and noun of sentences like “He opens the gate.” I also altered the frequency of the direct object and found longer utterance initiation times for sentences ending with a low-frequency vs. high-frequency object offering further support that the direct object was phonologically encoded at the time of utterance initiation. That phonological information for post-verbal elements was activated suggests that the grammatical importance of the verb does not restrict the extent of phonological planning. These results suggest that the phonological phrase is unit of planning, where all elements within a phonological phrase are encoded before articulation. Thus, consistent with other action sequencing behavior, there is significant phonological planning ahead in sentence production.
Phonological planning during sentence production: beyond the verb
(Frontiers in Psychology, 2011-11-04) Schnur, Tatiana T.
The current study addresses the extent of phonological planning during spontaneous sentence production. Previous work shows that at articulation, phonological encoding occurs for entire phrases, but encoding beyond the initial phrase may be due to the syntactic relevance of the verb in planning the utterance. I conducted three experiments to investigate whether phonological planning crosses multiple grammatical phrase boundaries (as defined by the number of lexical heads of phrase) within a single phonological phrase. Using the picture-word interference paradigm, I found in two separate experiments a significant phonological facilitation effect to both the verb and noun of sentences like “He opens the gate.” I also altered the frequency of the direct object and found longer utterance initiation times for sentences ending with a low-frequency vs. high-frequency object offering further support that the direct object was phonologically encoded at the time of utterance initiation. That phonological information for post-verbal elements was activated suggests that the grammatical importance of the verb does not restrict the extent of phonological planning. These results suggest that the phonological phrase is unit of planning, where all elements within a phonological phrase are encoded before articulation. Thus, consistent with other action sequencing behavior, there is significant phonological planning ahead in sentence production.
Role of Features and Categories in Representing Object Knowledge
(2015-04-21) Geng, Jingyi; Schnur, Tatiana T.; Martin, Randi C; Fischer-Baum, Simon; Cox, Steven; Hernandez, Arturo
Understanding how our knowledge about the world is organized can help us understand how we are able to access that knowledge to easily identify objects and communicate with others. One general view of object knowledge organization assumes that object knowledge is represented by how we perceive and interact with objects (for example features like the color or shape we see and touch) (i.e., feature view; e.g., Allport, 1985; Barsalou, 1999, 2008; Gallese & Lakoff, 2005; Tyler & Moss, 2001). In contrast, an alternative view hypothesizes that in addition to features from different modalities (e.g., visual, motor, and tactile), taxonomic (e.g., dog and rabbit are animal) and thematic category information (e.g., eating theme: a dog is chewing a bone) is also critical for representing object knowledge (i.e., feature-plus-category view; e.g., Crutch & Warrington, 2005, 2010; Patterson et al., 2007; Schwartz et al., 2011; Mirman & Graziano, 2012). In order to examine these two general views of object knowledge organization, I investigated whether feature and category information is activated when people access the meaning of words using both behavioral (i.e., response times and errors; Experiments 1 and 2) and functional magnetic resonance neuroimaging measures (Experiment 3). Consistent with the feature-plus-category view, Experiments 1 and 2 showed that when people access the meaning of words, this access was affected (slower/faster) by manipulating visual features (e.g., shape), taxonomic and thematic category information associated with objects. In support of the feature-plus-category view, Experiment 3 revealed that action features (e.g., cutting) associated with objects (e.g., saw) activated the motor brain region (i.e., primary motor cortex) and the taxonomic and thematic categories recruited the bilateral anterior temporal lobes and left temporo-parietal junction respectively. Taken together, my dissertation provides converging evidence from both behavioral and neuroimaging perspectives showing that both feature and category information play a key role in representing object concepts.
Role of features and categories in the organization of object knowledge: Evidence from adaptation fMRI
(Elsevier, 2016) Geng, Jingyi; Schnur, Tatiana T.
There are two general views regarding the organization of object knowledge. The feature-based view assumes that object knowledge is grounded in a widely distributed neural network in terms of sensory/function features (e.g., Warrington & Shallice, 1984), while the category-based view assumes in addition that object knowledge is organized by taxonomic and thematic categories (e.g., Schwartz etﾠal., 2011). Using a functional magnetic resonance imaging (fMRI) adaptation paradigm, we compared predictions from the feature- and category-based views by examining the neural substrates recruited as subjects read word pairs that were identical, taxonomically related, thematically related or unrelated while controlling for the function features involved across the two categories. We improved upon previous study designs and employed an fMRI adaptation task, obtaining results overall consistent with both the category-based and feature-based views. Consistent with the category-based view, we observed for both hypothesized regions of interest (ROI) and exploratory (whole-brain analyses) reduced activity in the left anterior temporal lobe (ATL) for taxonomically related versus unrelated word pairs, and for the exploratory analysis only, reduced activity in the right ATL. In addition, the exploratory analyses revealed reduced activity in the left temporo-parietal junction (TPJ) for thematically related versus unrelated word pairs. Consistent with the feature-based view, we found in the exploratory analyses that activity reduced in the bilateral precentral gyri (i.e., function regions) including part of premotor cortex as the function relatedness ratings increased. However, we did not find a relationship between adaptation effects in the bilateral ATLs and left TPJ and corresponding ratings of taxonomic/thematic relationships suggesting that the adaptation effects may potentially not reflect aspects of taxonomy that have been traditionally assumed. Together, our findings indicate that both feature and category information are important for the organization of object knowledge although the exact nature of those organization principles is an important question for future research.
Semantic interference in language production and comprehension: Same or separable loci?
(2014-04-22) Harvey, Denise Y.; Schnur, Tatiana T.; Martin, Randi C.; Fischer-Baum, Simon; O'Callaghan, Casey
The ability to speak and understand language is consciously a fast and easy process. However, the language system can err, either in normal processes or as a result of neural damage following stroke. Often, in both production and comprehension, errors are semantically related to the intended word, such as saying or understanding “cat” when the intended meaning is “dog”. This semantic interference (SI) effect suggests that the processing stages involved in language production and comprehension overlap to some extent. However, because language production and comprehension are usually investigated separately, this has led to different conclusions about how SI arises in each language modality. By most accounts, SI in production occurs at the lexical-semantic level, whereas SI in comprehension arises within the semantic system itself. In this dissertation, I distinguish between SI in production and comprehension by examining how (cognitive mechanisms) and where (neural loci) SI arises during picture naming and word-picture matching tasks that elicit SI by manipulating the semantic context with which target items appear. Aim I of my dissertation directly compared the behavioral characteristics of SI in healthy participants’ production and comprehension performance in order to elucidate the level and cognitive mechanism by which SI arises in each language modality. Aim II explored patients’ susceptibility to SI as it related to cortical gray matter and subcortical white matter damage. The results provided converging evidence that not only do the SI characteristics differ in production and comprehension, but also the neural locus of SI differs across language modality. However, the time course of SI is similar in both language modalities. Accordingly, I conclude SI arises when mapping meanings with words in production vs. mapping words with meanings in comprehension, but that the same cognitive mechanism operates over lexical-semantic processes across modalities. In the end, I argue that because of inherent differences between the order with which lexical and semantic representations are accessed in production vs. comprehension, the mechanism produces different behavioral manifestations of SI in each language modality and places differential demands on cognitive control mechanisms required to resolve interference.
Separating Semantic and Phonological Short-term Memory in Aphasic Patients Using a Novel Concurrent Probe Paradigm
(2014-02-25) Dial, Heather; Martin, Randi C.; Schnur, Tatiana T.; Logan, Jessica M.
Previous research suggests that short-term memory (STM) processes are separable into at least two buffers: a lexical-semantic and a phonological buffer. While there are multiple tasks used to measure phonological STM, only one task is commonly employed to test semantic STM, the category probe task. The current study used a novel paradigm, the concurrent probe paradigm (Shivde & Anderson, 2011), to measure semantic and phonological maintenance in aphasia patients. In Experiment 1, which evaluated semantic maintenance, we replicated the findings of Shivde and Anderson (2011) with older adults and revealed dissociations in patient performance depending on the type of STM deficit. The concurrent probe paradigm provided converging evidence with the category probe task in measuring semantic STM deficits. In Experiments 2 and 3, we applied the task to phonological maintenance. We replicated the findings of Shivde and Anderson (2011) with older adults, but for patients the results were less clear.
Testing the semantic control hypothesis for stroke aphasics with semantic deficits
(2012-09-05) Hassan, Azli; Martin, Randi C.; Schnur, Tatiana T.; Lane, David M.
Some studies of stroke patients with semantic deficits have found no effect of word frequency on semantic tasks, as well as inconsistent performance across items and tasks. A deficit in semantic control has been suggested as the source of the deficit - i.e., an inability to focus on semantic features appropriate to the task. In the present study, two stroke patients performed significantly better in single-distractor versions (low semantic control) than multiple-distractor versions of semantic tasks (high semantic control) of comprehension tasks, which appears consistent with the semantic control hypothesis. On the other hand, two aphasic patients showed substantially better performance for auditory than visual presentation of words in comprehension tasks – a finding that is not expected on the basis of semantic control. Experiment 1 evaluated whether performance on a multiple-distractor comprehension task could be predicted solely on the basis of performance on a single-distractor version using Luce’s choice axiom. Single distractor performance significantly predicted performance and no convincing evidence was obtained for a role for semantic control. Experiment 2, which examined the modality effect, showed that for one of the patients, worse performance with auditory presentation was most likely due to rapid decay of phonological representations. For the other, worse performance was most likely due to a disruption to phonological representations of words or to their connection to semantic representations. In all, the results suggest that word comprehension deficits in aphasia can result from a variety of sources and not all are due to semantic control deficits.
The distractor frequency effect in Stroop and picture-word interference paradigms
(2010) Geng, Jingyi; Schnur, Tatiana T.
The color naming (Stroop) and picture-word interference (PWI) paradigms play a pivotal role in theorizing about cognitive processes in general, and language production in particular. Despite their assumed similarities, there exist discrepancies. In this study, I compared the effect of distractor word frequency between Stroop and PWI paradigms (in PWI picture naming is faster for high frequency than low frequency word distractors; Miozzo & Caramazza, 2003). In five experiments, I confirm the presence of DFE in both Stroop and PWI paradigms when the naming latencies are longer but the absence of DFE in both paradigms when the naming latencies are shorter and found that when naming latencies are fast, the distractor words are most likely processed to the phonological level by the time targets are named in both paradigms in the last experiment. Thus, my results are consistent with the assumption that the two paradigms operate in the same manner.
The Representation of Concrete and Abstract Concepts: Categorical Versus Associative Relationships
(American Psychological Association, 2014) Geng, Jingyi; Schnur, Tatiana T.
In 4 word-translation experiments, we examined the different representational frameworks theory (Crutch & Warrington, 2005; 2010) that concrete words are represented primarily by category, whereas abstract words are represented by association. In our experiments, Chinese-English bilingual speakers were presented with an auditory Chinese word and 3 or 4 written English words simultaneously and asked to select the English word that corresponded to the auditory word. For both abstract and concrete words, higher error rates and longer response times were observed when the English words were categorically or associatively related compared to the unrelated conditions and the magnitude of the categorical effect was bigger than the associative effect. These results challenge the different representational frameworks theory and suggest that although category and association are important for representing abstract and concrete concepts, category plays a greater role for both types of words.
Verb Production and the Semantic Interference Effect
(2002) Schnur, Tatiana T.; Costa, Albert; Caramazza, Alfonso; Institute for Cognitive Science
In three experiments, we explored the semantic interference effect in verb production with the picture-word interference paradigm. Experiments 1 and 3 addressed whether there is an effect of semantically related distracters on gerundial verb production; In Experiment 2, we explored the effect in naming verbs in sentence production and the third person singular form. The semantic interference effect was found in two of the three experiments. However, the effect was inconsistent when transitive and intransitive verbs were analyzed separately. The results are discussed in the context of models of the semantic interference effect in lexical access.
White Matter Correlates of Domain-Specific Working Memory
(MDPI, 2023) Horne, Autumn; Ding, Junhua; Schnur, Tatiana T.; Martin, Randi C.
Prior evidence suggests domain-specific working memory (WM) buffers for maintaining phonological (i.e., speech sound) and semantic (i.e., meaning) information. The phonological WM buffer’s proposed location is in the left supramarginal gyrus (SMG), whereas semantic WM has been related to the left inferior frontal gyrus (IFG), the middle frontal gyrus (MFG), and the angular gyrus (AG). However, less is known about the white matter correlates of phonological and semantic WM. We tested 45 individuals with left hemisphere brain damage on single word processing, phonological WM, and semantic WM tasks and obtained T1 and diffusion weighted neuroimaging. Virtual dissections were performed for each participants’ arcuate fasciculus (AF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), middle longitudinal fasciculus (MLF), and uncinate fasciculus (UF), which connect the proposed domain-specific WM buffers with perceptual or processing regions. The results showed that the left ILF, MLF, IFOF, and the direct segment of the AF were related to semantic WM performance. Phonological WM was related to both the left ILF and the MLF. This work informs our understanding of the white matter correlates of WM, especially semantic WM, which has not previously been investigated. In addition, this work helps to adjudicate between theories of verbal WM, providing some evidence for separate pathways supporting phonological and semantic WM.

Browsing by Author "Schnur, Tatiana T."

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