Browsing by Author "Ingvar, Martin"
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- Broca's region: A causal role in implicit processing of grammars with crossed non-adjacent dependenciesPublication . Udden, Julia; Ingvar, Martin; Hagoort, Peter; Petersson, Karl MagnusNon-adjacent dependencies are challenging for the language learning machinery and are acquired later than adjacent dependencies. In this transcranial magnetic stimulation (TMS) study, we show that participants successfully discriminated between grammatical and non-grammatical sequences after having implicitly acquired an artificial language with crossed non-adjacent dependencies. Subsequent to transcranial magnetic stimulation of Broca's region, discrimination was impaired compared to when a language-irrelevant control region (vertex) was stimulated. These results support the view that Broca's region is engaged in structured sequence processing and extend previous functional neuroimaging results on artificial grammar learning (AGL) in two directions: first, the results establish that Broca's region is a causal component in the processing of non-adjacent dependencies, and second, they show that implicit processing of non-adjacent dependencies engages Broca's region. Since patients with lesions in Broca's region do not always show grammatical processing difficulties, the result that Broca's region is causally linked to processing of non-adjacent dependencies is a step towards clarification of the exact nature of syntactic deficits caused by lesions or perturbation to Broca's region. Our findings are consistent with previous results and support a role for Broca's region in general structured sequence processing, rather than a specific role for the processing of hierarchically organized sentence structure. (C) 2017 Published by Elsevier B.V.
- Color makes a difference: two-dimensional object naming in literate and illiterate subjectsPublication . Reis, Alexandra; Faísca, Luís; Ingvar, Martin; Petersson, Karl MagnusPrevious work has shown that illiterate subjects are better at naming two-dimensional representations of real objects when presented as colored photos as compared to black and white drawings. This raises the question if color or textural details selectively improve object recognition and naming in illiterate compared to literate subjects. In this study, we investigated whether the surface texture and/or color of objects is used to access stored object knowledge in illiterate subjects. A group of illiterate subjects and a matched literate control group were compared on an immediate object naming task with four conditions: color and black and white (i.e., grey-scaled) photos, as well as color and black and white (i.e., grey-scaled) drawings of common everyday objects. The results show that illiterate subjects perform signiWcantly better when the stimuli are colored and this eVect is independent of the photographic detail. In addition, there were signiWcant diVerences between the literacy groups in the black and white condition for both drawings and photos. These results suggest that color object information contributes to object recognition. This eVect was particularly prominent in the illiterate group.
- Disruption of order information by irrelevant items: A serial recognition paradigmPublication . Gisselgard, Jens; Udden, Julia; Ingvar, Martin; Petersson, Karl Magnusirrelevant speech effect (ISE) is defined as a decrement in visually presented digit-list short-term memory performance due to exposure to irrelevant auditory material. Perhaps the most successful theoretical explanation of the effect is the changing state hypothesis. This hypothesis explains the effect in terms of confusion between amodal serial order cues, and represents a view based on the interference caused by the processing of similar order information of the visual and auditory materials. An alternative view suggests that the interference occurs as a consequence of the similarity between the visual and auditory contents of the stimuli. An important argument for the former view is the observation that ISE is almost exclusively observed in tasks that require memory for serial order. However, most short-term memory tasks require that both item and order information be retained in memory. An ideal task to investigate the sensitivity of maintenance of serial order to irrelevant speech would be one that calls upon order information but not item information. One task that is particularly suited to address this issue is serial recognition. In a typical serial recognition task, a list of items is presented and then probed by the same list in which the order of two adjacent items has been transposed. Due to the re-presentation of the encoding string, serial recognition requires primarily the serial order to be maintained while the content of the presented items is deemphasized. In demonstrating a highly significant ISE of changing versus steady-state auditory items in a serial recognition task, the present finding lends support for and extends previous empirical findings suggesting that irrelevant speech has the potential to interfere with the coding of the order of the items to be memorized. (c) 2006 Elsevier B.V. All rights reserved.
- Formal schooling influences two- but not three-dimensional naming skillsPublication . Reis, Alexandra; Magnus Petersson, Karl; Castro-Caldas, A.; Ingvar, MartinThe modulatory influence of literacy on the cognitive system of the human brain has been indicated in behavioral, neuroanatomic, and functional neuroimaging studies. In this study we explored the functional consequences of formal education and the acquisition of an alphabetic written language on two- and three-dimensional visual naming. The results show that illiterate subjects perform significantly worse on immediate naming of two-dimensional representations of common everyday objects compared to literate subjects, both in terms of accuracy and reaction times. In contrast, there was no significant difference when the subjects named the corresponding real objects. The results suggest that formal education and learning to read and to write modulate the cognitive process involved in processing two- but not three-dimensional representations of common everyday objects. Both the results of the reaction time and the error pattern analyses can be interpreted as indicating that the major influence of literacy affects the visual system or the interaction between the visual and the language systems. We suggest that the visual system in a wide sense and/or the interface between the visual and the language system are differently formatted in literate and illiterate subjects. In other words, we hypothesize that the pattern of interactions in the functional-anatomical networks subserving visual naming, that is, the interactions within and between the visual and language processing networks, differ in literate and illiterate subjects. (C) 2001 Elsevier Science.
- Implicit acquisition of grammars with crossed and nested non-adjacent dependencies: investigating the push-down stack modelPublication . Udden, Julia; Ingvar, Martin; Hagoort, Peter; Petersson, Karl MagnusA recent hypothesis in empirical brain research on language is that the fundamental difference between animal and human communication systems is captured by the distinction between finite-state and more complex phrase-structure grammars, such as context-free and context-sensitive grammars. However, the relevance of this distinction for the study of language as a neurobiological system has been questioned and it has been suggested that a more relevant and partly analogous distinction is that between non-adjacent and adjacent dependencies. Online memory resources are central to the processing of non-adjacent dependencies as information has to be maintained across intervening material. One proposal is that an external memory device in the form of a limited push-down stack is used to process non-adjacent dependencies. We tested this hypothesis in an artificial grammar learning paradigm where subjects acquired non-adjacent dependencies implicitly. Generally, we found no qualitative differences between the acquisition of non-adjacent dependencies and adjacent dependencies. This suggests that although the acquisition of non-adjacent dependencies requires more exposure to the acquisition material, it utilizes the same mechanisms used for acquiring adjacent dependencies. We challenge the push-down stack model further by testing its processing predictions for nested and crossed multiple non-adjacent dependencies. The push-down stack model is partly supported by the results, and we suggest that stack-like properties are some among many natural properties characterizing the underlying neurophysiological mechanisms that implement the online memory resources used in language and structured sequence processing.
- Instruction effects in implicit artificial grammar learning: a preference for grammaticalityPublication . Forkstam, Christian; Elwer, Asa; Ingvar, Martin; Petersson, Karl MagnusHuman implicit learning can be investigated with implicit artificial grammar learning, a paradigm that has been proposed as a simple model for aspects of natural language acquisition. In the present study we compared the typical yes-no grammaticality classification, with yes-no preference classification. in the case of preference instruction no reference to the underlying generative mechanism (i.e., grammar) is needed and the subjects are therefore completely uninformed about an underlying structure in the acquisition material. in experiment 1, subjects engaged in a short-term memory task using only grammatical strings without performance feedback for 5 days. As a result of the 5 acquisition days, classification performance was independent of instruction type and both the preference and the grammaticality group acquired relevant knowledge of the underlying generative mechanism to a similar degree. Changing the grammatical stings to random strings in the acquisition material (experiment 2) resulted in classification being driven by local substring familiarity. Contrasting repeated vs. non-repeated preference classification (experiment 3) showed that the effect of local substring familiarity decreases with repeated classification. This was not the case for repeated grammaticality classifications. We conclude that classification performance is largely independent of instruction type and that forced-choice preference classification is equivalent to the typical grammaticality classification. (C) 2008 Elsevier B.V. All rights reserved.
- Interaction between a verbal working memory network and the medial temporal lobePublication . Petersson, Karl Magnus; Gisselgard, Jens; Gretzer, Monica; Ingvar, MartinThe irrelevant speech effect illustrates that sounds that are irrelevant to a visually presented short-term memory task still interfere with neuronal function. In the present study we explore the functional and effective connectivity of such interference. The functional connectivity analysis suggested an interaction between the level of irrelevant speech and the correlation between in particular the left superior temporal region, associated with verbal working memory, and the left medial temporal lobe. Based on this psycho-physiological interaction, and to broaden the understanding of this result, we performed a network analysis, using a simple network model for verbal working memory, to analyze its interaction with the medial temporal lobe memory system. The results showed dissociations in terms of network interactions between frontal as well as parietal and temporal areas in relation to the medial temporal lobe. The results of the present study suggest that a transition from phonological loop processing towards an engagement of episodic processing might take place during the processing of interfering irrelevant sounds. We speculate that, in response to the irrelevant sounds, this reflects a dynamic shift in processing as suggested by a closer interaction between a verbal working memory system and the medial temporal lobe memory system. (c) 2006 Elsevier Inc. All rights reserved.
- Literacy: exploring working memory systemsPublication . Silva, Catarina; Faísca, Luís; Ingvar, Martin; Petersson, Karl Magnus; Reis, AlexandraPrevious research showed an important association between reading and writing skills (literacy) and the phonological loop. However, the effects of literacy on other working memory components remain unclear. In this study, we investigated performance of illiterate subjects and their matched literate controls on verbal and nonverbal working memory tasks. Results revealed that the phonological loop is significantly influenced by literacy, while the visuospatial sketchpad appears to be less affected or not at all. Results also suggest that the central executive might be influenced by literacy, possibly as an expression of cognitive reserve.
- Predictability modulates the affective and sensory-discriminative neural processing of painPublication . Carlsson, Katrina; Andersson, Jesper; Petrovic, Predrag; Petersson, Karl Magnus; Ohman, Arne; Ingvar, MartinKnowing what is going to happen next, that is, the capacity to predict upcoming events, modulates the extent to which aversive stimuli induce stress and anxiety. We explored this issue by manipulating the temporal predictability of aversive events by means of a visual cue, which was either correlated or uncorrelated with pain stimuli (electric shocks). Subjects reported lower levels of anxiety, negative valence and pain intensity when shocks were predictable. In addition to attenuate focus on danger, predictability allows for correct temporal estimation of, and selective attention to, the sensory input. With functional magnetic resonance imaging, we found that predictability was related to enhanced activity in relevant sensory-discriminative processing areas, such as the primary and secondary sensory cortex and posterior insula. In contrast, the unpredictable more aversive context was correlated to brain activity in the anterior insula and the orbitofrontal cortex, areas associated with affective pain processing. This context also prompted increased activity in the posterior parietal cortex and lateral prefrontal cortex that we attribute to enhanced alertness and sustained attention during unpredictability. (c) 2006 Elsevier Inc. All rights reserved.
- Semantic interference on a phonological task in illiterate subjectsPublication . Reis, Alexandra; Faísca, Luís; Mendonca, Susana; Ingvar, Martin; Petersson, Karl MagnusScandinavian Journal of Psychology, 2007, 48, 69–74 DOI: 10.1111/j.1467-9450.2006.00544.x © 2007 The Authors. Journal compilation © 2007 The Scandinavian Psychological Associations. Published by Blackwell Publishing L td., 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA. ISSN 0036-5564. Blackwell Publishing Ltd Health and Disability Semantic interference on a phonological task in illiterate subjects ALEXANDRA REIS, 1,2,3 L UÍS FAÍSCA, 2,3 SUSANA MENDONÇA, 2 MARTIN INGVAR 1 and KARL MAGNUS PETERSSON 1,3,4 1 Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden 2 Cognitive Neuroscience Research Group, Departamento de Psicologia, Faculdade de Ciências Humanas e Sociais, Universidade do Alg arve, Faro, Por tugal 3 Center for Intelligent Systems, Universidade do Algarve, Faro, Portugal 4 F. C. Donders Centre for Cognitive Neuroimaging, Radboud University Nijmegen, The Netherlands R eis, A., Faísca, L., Mendonça, S., Ingvar, M. & Petersson, K. M. (2007). Semantic interference on a phonological task in illit erate subjects. Scandinavian Journal of Psychology , 48 , 69–74. Previous research suggests that learning an alphabetic written language influences aspects of the auditory-verbal language syste m. In this study, we e xamined whether literacy influences the notion of words as phonological units independent of lexical semantics in literate a nd illiterate subjects. Subjects had to decide which item in a word- or pseudoword pair was phonologically longest. By manipulating the relat ionship between r eferent size and phonological length in three word conditions (congruent, neutral, and incongruent) we could examine to what e xtent subjects f ocused on form rather than meaning of the stimulus material. Moreover, the pseudoword condition allowed us to examine global p honological aw areness independent of lexical semantics. The results showed that literate performed significantly better than illiterate subj ects in the neutral and incongruent word conditions as well as in the pseudoword condition. The illiterate group performed least well in the incong ruent condition and significantly better in the pseudoword condition compared to the neutral and incongruent word conditions and suggest that pe rformance on phonological word length comparisons is dependent on literacy. In addition, the results show that the illiter a te participant s are able to perceive and process phonological length, albeit less well than the literate subjects, when no semantic interference is present . In conclusion, the present results confirm and extend the finding that illiterate subjects are biased towards semantic-conceptual-pragmatic type s of cognitive processing