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Contributions of response set and semantic relatedness to cross-modal Stroop-like picture-word interference in children and adults.

Resistance to interference from irrelevant auditory stimuli undergoes development throughout childhood. To test whether semantic processes account for age-related changes in a Stroop-like picture-word interference effect, children (3- to 12-year-olds) and adults named pictures while listening to words varying in terms of semantic relatedness to the pictures and response set membership. In Experiments 1 and 2, with animal and clothing pictures, the interference effect observed in children, but not in adults, depended on the distractors' status as members of the response set. In Experiment 3, with unrelated pictures, adults, but not children, showed greater interference for trials with distractors in the response set. These results indicate developmental changes in picture-word interference involving the establishment of a response set in working memory.

Adolescent↗

Visual cortex activation in late-onset, Braille naive blind individuals: an fMRI study during semantic and phonological tasks with heard words.

Visual cortex activity in the blind has been shown in Braille literate people, which raise the question of whether Braille literacy influences cross-modal reorganization. We used fMRI to examine visual cortex activation during semantic and phonological tasks with auditory presentation of words in two late-onset blind individuals who lacked Braille literacy. Multiple visual cortical regions were activated in the Braille naive individuals. Positive BOLD responses were noted in lower tier visuotopic (e.g., V1, V2, VP, and V3) and several higher tier visual areas (e.g., V4v, V8, and BA 37). Activity was more extensive and cross-correlation magnitudes were greater during the semantic compared to the phonological task. These results with Braille naive individuals plausibly suggest that visual deprivation alone induces visual cortex reorganization. Cross-modal reorganization of lower tier visual areas may be recruited by developing skills in attending to selected non-visual inputs (e.g., Braille literacy, enhanced auditory skills). Such learning might strengthen remote connections with multisensory cortical areas. Of necessity, the Braille naive participants must attend to auditory stimulation for language. We hypothesize that learning to attend to non-visual inputs probably strengthens the remaining active synapses following visual deprivation, and thereby, increases cross-modal activation of lower tier visual areas when performing highly demanding non-visual tasks of which reading Braille is just one example.

Adult↗

Dynamical systems and cognitive linguistics: toward an active morphodynamical semantics.

We propose a novel dynamical system approach to cognitive linguistics based on cellular automata and spiking neural networks. How can the same relationship 'in' apply to containers as different as 'box', 'tree' or 'bowl'? Our objective is to categorize the infinite diversity of schematic visual scenes into a small set of grammatical elements and elucidate the topology of language. Gestalt-inspired semantic studies have shown that spatial prepositions such as 'in' or 'above' are neutral toward the shape and size of objects. We suggest that this invariance can be explained by introducing morphodynamical transforms, which erase image details and create virtual structures or singularities (boundaries, skeleton), and call this paradigm 'active semantics'. Singularities arise from a large-scale lattice of coupled excitable units exhibiting spatiotemporal pattern formation, in particular traveling waves. This work addresses the crucial cognitive mechanisms of spatial schematization and categorization at the interface between vision and language and anchors them to expansion processes such as activity diffusion or wave propagation.

Algorithms↗

The neural basis for novel semantic categorization.

We monitored regional cerebral activity with BOLD fMRI during acquisition of a novel semantic category and subsequent categorization of test stimuli by a rule-based strategy or a similarity-based strategy. We observed different patterns of activation in direct comparisons of rule- and similarity-based categorization. During rule-based category acquisition, subjects recruited anterior cingulate, thalamic, and parietal regions to support selective attention to perceptual features, and left inferior frontal cortex to helps maintain rules in working memory. Subsequent rule-based categorization revealed anterior cingulate and parietal activation while judging stimuli whose conformity with the rules was readily apparent, and left inferior frontal recruitment during judgments of stimuli whose conformity was less apparent. By comparison, similarity-based category acquisition showed recruitment of anterior prefrontal and posterior cingulate regions, presumably to support successful retrieval of previously encountered exemplars from long-term memory, and bilateral temporal-parietal activation for perceptual feature integration. Subsequent similarity-based categorization revealed temporal-parietal, posterior cingulate, and anterior prefrontal activation. These findings suggest that large-scale networks support relatively distinct categorization processes during the acquisition and judgment of semantic category knowledge.

Adult↗

Separating semantic conflict and response conflict in the Stroop task: a functional MRI study.

Attentive behavior requires the ability to perform in the face of distraction. Distracting information can cause conflict at any level along the information processing stream. However, it is not yet known whether the brain has distinct subsystems dedicated to detecting and resolving these different forms of distraction. Although previous studies have localized brain activity during semantic and response conflict, no prior study has specifically determined whether these activations occur in distinct or overlapping regions. We used a modified version of the Stroop color-word task, by which we were able to separate semantic from response conflict. Behavioral data indicate that these two kinds of conflict both contribute to the overall Stroop interference effect, while fMRI data indicate that they elicit non-overlapping activation in anterior cingulate, prefrontal, and parietal brain regions. These results suggest that the brain has distinct but parallel attentional mechanisms for resolving these different forms of cognitive interference.

Adult↗

Qualitative aspects of verbal fluency in HIV-associated dementia: a deficit in rule-guided lexical-semantic search processes?

HIV-associated dementia (HAD) is widely considered a "subcortical" dementia that involves a disruption of frontal-basal ganglia circuits. Deficits in verbal fluency are common in HAD; however, the cognitive underpinnings of these deficits are not well understood. To elucidate the cognitive mechanisms underlying the diminished verbal fluency output in HAD, we examined several qualitative aspects of letter fluency in 21 individuals with HAD, 51 nondemented persons with HIV infection (HIV+), and 30 healthy controls (HC) who were comparable for age, education, sex, ethnicity, and estimated premorbid verbal intelligence. The verbal fluency protocols were scored to obtain the total number of correct words, average phonemic cluster size, total number of switches between phonemic clusters, and the proportion of error responses (i.e., intrusions, perseverations, and variants). Consistent with prior research, HAD participants produced significantly fewer total correct words relative to the HC and nondemented HIV+ groups. The HAD group also demonstrated fewer switches and a higher proportion of response errors (especially intrusion errors), but no differences were observed in average cluster size. Findings are interpreted as reflecting a disruption of rule-guided lexical-semantic search strategies in HAD, perhaps mediated by prefrontal-striatal circuit dysfunction, rather than depleted lexical-semantic memory stores.

AIDS Dementia Complex↗

Differing neuropsychological and neuroanatomical correlates of abnormal reading in early-stage semantic dementia and dementia of the Alzheimer type.

Individuals with semantic dementia (SD) were differentiated neuropsychologically from individuals with dementia of the Alzheimer type (DAT) at very mild-to-mild stages (clinical dementia rating 0.5 or 1). A picture naming and recognition memory experiment provided a particularly useful probe for early identification, with SD individuals showing preserved picture recognition memory and impaired naming, and DAT individuals tending to show the reverse dissociation. The identification of an early SD group provided the opportunity to inform models of reading by exploring the influence of isolated lexical semantic impairment on reading regular words. Results demonstrated prolonged latency in both SD and DAT group reading compared to a control group but exaggerated influence of frequency and length only for the SD group. The SD reading pattern was associated with focal atrophy of the left temporal pole. These cognitive-neuroanatomical findings suggest a role for the left temporal pole in lexical/semantic components of reading and demonstrate that cortical thickness differences in the left temporal pole correlate with prolonged latency associated with increased reliance on sublexical components of reading.

Aged↗

The age of acquisition of words produced in a semantic fluency task can reliably differentiate normal from pathological age related cognitive decline.

This study examined differences in the characteristics of words produced by healthy elderly controls and by patients with Alzheimer's disease (AD) in a semantic fluency task (generating words from the categories of animals and fruit). Ninety-six AD patients (MMSE 13-29) and 40 controls matched for age and socio-cultural background completed a semantic fluency task. Length, frequency, typicality and age of acquisition (AoA) values were obtained for each word generated. In comparison with controls, AD patients generated fewer items, and their items were higher in frequency, shorter in length, more typical and earlier in AoA. Discriminant function analysis showed that AoA was the best predictor of group membership (patient/control). The mean AoA of words generated correctly classified 95% of controls and 88% of patients.

Age of Onset↗

A horse of a different colour: do patients with semantic dementia recognise different versions of the same object as the same?

Ten patients with semantic dementia resulting from bilateral anterior temporal lobe atrophy, and 10 matched controls, were tested on an object recognition task in which they were invited to choose (from a four-item array) the picture representing "the same thing" as an object picture that they had just inspected and attempted to name. The target in the response array was never physically identical to the studied picture but differed from it - in the various conditions - in size, angle of view, colour or exemplar (e.g. a different breed of dog). In one test block for each patient, the response array was presented immediately after the studied picture was removed; in another block, a 2 min filled delay was inserted between study and test. The patients performed relatively well when the studied object and target response differed only in the size of the picture on the page, but were significantly impaired as a group in the other three type-of-change conditions, even with no delay between study and test. The five patients whose structural brain imaging revealed major right-temporal atrophy were more impaired overall, and also more affected by the 2 min delay, than the five patients with an asymmetric pattern characterised by predominant left-sided atrophy. These results are interpreted in terms of a hypothesis that successful classification of an object token as an object type is not a pre-semantic ability but rather results from interaction of perceptual and conceptual processing.

Adult↗

The "hidden" semantic category dissociation in mild-moderate Alzheimer's disease patients.

In patients manifesting mild-moderate Alzheimer's disease (AD), lexical semantic tasks are known to be influenced by several variables which should be adequately taken into account when studying semantic category dissociations. The following study provides indexes of three new variables (imageability (I), percentage of name agreement (pNA) and number of target alternatives (nTA)) and investigates their role in naming in a group of people with AD and in matched older adults controls. Forty young healthy participants rated I, pNA and nTA of 155 stimuli (including living and non-living items) from and sets. Forty-eight people with mild-moderate AD and 40 older adults were given the two naming tests and their naming ratings were analysed with a two-way ANOVA (two groupsxtwo categories) to assess category specificity and the effect of interaction. The influence of relevant concomitant variables in naming was measured using a multiple regression analysis. Semi-partial correlations were carried out to assess the independent contribution of each variable to naming. We found that living items were more imageable and had fewer lexical alternatives and higher name agreement than non-living items. We also found that controls significantly named better than AD patients (F=37.551, p<.001), whilst the two-way ANOVA showed no significant effect of category (F=.649, p=.423). Notably category effect emerged when assessing its independent contribution performing a semi-partial correlation (beta=-.278, p<.001) which kept the effect of relevant concomitant variables under control. Our results confirm that category dissociation does emerge in mild-moderate AD patients when the effect of relevant concomitant variables is adequately taken into account. The hypothesis that the highly correlated properties of items from biological categories may play a protective effect on living things, making them less prone to impairment in the early stages of AD, is discussed.

Age Factors↗

Memory enhancement by a semantically unrelated emotional arousal source induced after learning.

It has been well established that moderate physiological or emotional arousal modulates memory. However, there is some controversy about whether the source of arousal must be semantically related to the information to be remembered. To test this idea, 35 healthy young adult participants learned a list of common nouns and afterward viewed a semantically unrelated, neutral or emotionally arousing videotape. The tape was shown after learning to prevent arousal effects on encoding or attention, instead influencing memory consolidation. Heart rate increase was significantly greater in the arousal group, and negative affect was significantly less reported in the non-arousal group after the video. The arousal group remembered significantly more words than the non-arousal group at both 30 min and 24 h delays, despite comparable group memory performance prior to the arousal manipulation. These results demonstrate that emotional arousal, even from an unrelated source, is capable of modulating memory consolidation. Potential reasons for contradictory findings in some previous studies, such as the timing of "delayed" memory tests, are discussed.

Adult↗

N400 as an index of semantic expectancies: differential effects of alcohol and cocaine dependence.

BACKGROUND: Chronic substance abuse has been associated with decrements in the processing and expression of language. The present study utilized the N400 event-related electroencephalographic potential to index semantic processing in 133 adults with (n=49) or without (n=84) a history of alcohol and/or cocaine dependence. The contributions of age, gender, and comorbid marijuana and nicotine dependence, and antisocial symptomology to N400 decrements were either covaried or controlled. METHODS: A continuous series of 300 stimuli was presented for 150 ms each (interstimulus interval=1475 ms) on a computer screen. The series was arranged such that a word (approximately 17% of stimuli) immediately preceded presentations of its antonym (primed condition; approximately 17% of stimuli), or a semantically unrelated word (unprimed condition; approximately 17% of stimuli). The remaining 50% of stimuli consisted of unpronounceable letter combinations (non-word condition). EEG responses to the antonyms, unrelated words, and letter jumbles were retained for analysis. Throughout the task, the subject pressed response keys to discriminate words from non-words. RESULTS: Analyses revealed a detrimental effect of alcohol dependence on N400 amplitude and no significant main or interactive effects of cocaine dependence. CONCLUSION: The present findings suggest that alcohol-dependent individuals may exhibit verbal processing decrements. These findings also challenge hypotheses suggesting that the combined use of cocaine and alcohol is more deleterious to brain function than alcohol use alone.

Adolescent↗

Event-related potential index of semantic mnemonic dysfunction in abstinent alcoholics.

BACKGROUND: The objective of the study was to expand the investigation of the match/mismatch mnemonic impairment in the semantic domain in sober alcoholics. METHODS: Event-related potentials (ERPs) were recorded from 28 healthy adults and 36 sober alcoholics in a category (either animals or fruits/vegetables) match/nonmatch S1-S2 paradigm. RESULTS: There was a significant interaction of ERP amplitude (c3) between groups (controls vs. alcoholics) and stimulus conditions (category match vs. nonmatch) at the posterior brain regions; the c3 component was smaller for the category match than for nonmatch trials in controls, with the absence of such c3 differences in alcoholics. There were no significant ERP differences between the two groups in processing the sample stimuli. The ERPs c2) elicited by the animal category were larger than those for the vegetable category in both groups. The alcoholics showed prominent suppressed activation of left temporooccipital brain regions under both matching and nonmatching conditions, as demonstrated by the current source density maps. The alcoholics were also slower and less accurate than the controls in judging both category matching and nonmatching stimuli, while neither of the two groups demonstrated shorter response times to the matching stimuli. CONCLUSIONS: These data suggest that alcoholics are less efficient in the semantic mnemonic match/nonmatch process, and are less likely to be deteriorated in the stage of forming the template for such match/nonmatch comparisons.

Adult↗

Semantic negative priming in picture categorization and naming.

Ignoring a particular stimulus can hamper subsequent attended processing of the same stimulus, a phenomenon known as 'negative priming'. Previous research has yielded partial support for the claim that the effect results from the attentional inhibition of central representations, as suggested by the fact that it appears to extend to semantic associates of ignored stimuli. In the current experiment, participants categorized or named pictorial stimuli with superimposed distractor pictures; the effect of unrelated, identical, or categorically related previously ignored pictures was investigated. Furthermore, visual similarity between categorically related picture pairs was manipulated in the naming task. The results indicated negative priming from identical ignored pictures irrespective of task. However, semantic negative priming was observed in the categorization task only. In the naming task, even visual overlap between categorically related picture pairs failed to induce negative priming. These findings argue against a central locus of the negative priming effect.

Adult↗

Scalar implicatures: experiments at the semantics-pragmatics interface.

In this article we present two sets of experiments designed to investigate the acquisition of scalar implicatures. Scalar implicatures arise in examples like Some professors are famous where the speaker's use of some typically indicates that s/he had reasons not to use a more informative term, e.g. all. Some professors are famous therefore gives rise to the implicature that not all professors are famous. Recent studies on the development of pragmatics suggest that preschool children are often insensitive to such implicatures when they interpret scalar terms (Cognition 78 (2001) 165; Chierchia, G., Crain, S., Guasti, M.T., Gualmini, A., & Meroni, L. (2001). The acquisition of disjunction: evidence for a grammatical view of scalar implicatures. In A.H.-J. Do, L. Dominguez, & A. Johansen (Eds.), Proceedings of the 25th Boston University Conference on Language Development (pp. 157-168). Somerville, MA: Cascadilla Press; Musolino, J., & Lidz, J. (2002). Preschool logic: truth and felicity in the acquisition of quantification. In B. Skarabela, S. Fish, & A.H.-J. Do, Proceedings of the 26th Boston University Conference on Language Development (pp. 406-416). Somerville, MA: Cascadilla Press). This conclusion raises two important questions: (a) are all scalar terms treated in the same way by young children?, and (b) does the child's difficulty reflect a genuine inability to derive scalar implicatures or is it due to demands imposed by the experimental task on an otherwise pragmatically savvy child? Experiment 1 addresses the first question by testing a group of 30 5-year-olds and 30 adults (all native speakers of Greek) on three different scales, ( ), ( ) and ( ). In each case, subjects were presented with contexts which satisfied the semantic content of the stronger (i.e. more informative) terms on each scale (i.e. all, three and finish) but were described using the weaker terms of the scales (i.e. some, two, start). We found that, while adults overwhelmingly rejected these infelicitous descriptions, children almost never did so. Children also differed from adults in that their rejection rate on the numerical scale was reliably higher than on the two other scales. In order to address question (b), we trained a group of 30 5-year-olds to detect infelicitous statements. We then presented them with modified versions of the stories of Experiment 1, which now more readily invited scalar inferences. These manipulations gave rise to significantly higher rejection rates than those observed in Experiment 1. Overall, these findings indicate that children do not treat all scalar terms alike and, more importantly, that children's ability to derive scalar implicatures is affected by their awareness of the goal of the task. Developmental and methodological implications as well as theoretical implications for the semantics of numeral terms are discussed.

Child, Preschool↗

Taking on semantic commitments, II: Collective versus distributive readings.

In earlier work, Frazier and Rayner (1990) provided evidence for a processing principle termed the Minimal Semantic Commitment (MSC)hypothesis. In the present study, we used the MSC hypothesis as a starting point in addressing the issue of when to treat mental representations as vague versus determinate and ambiguous. Given ambiguous representations, the MSC hypothesis predicts that the processor will commit to one interpretation (the grammatical ambiguity hypothesis). On the other hand, given a single underspecified representation, the MSC hypothesis predicts that the processor will await disambiguating information before fully committing to an interpretation (the vagueness hypothesis). In an experiment designed to evaluate these hypotheses with respect to the representation of distributivity, participants' eye movements were recorded as they read sentences containing distributive or collective predicates that were either disambiguated by a preceding adverb or left locally ambiguous by delaying the disambiguating adverb until the end of the predicate. The results suggested that a semantic commitment is made in locally indeterminate cases as evidenced by a significant interaction of ambiguity and distributivity in first pass times, total times, and regressions. If the difficulty of distributives simply reflected the difficulty of postulating a distributive operator when evidence warranting it is encountered, then no interaction would be expected. Hence we argue that the distributive/collective distinction is treated as a matter of ambiguity rather than as one of vagueness. In the absence of evidence for a distributive reading, the processor commits itself to a collective reading sometime during the processing of the predicate (before the disambiguation in our late disambiguation examples). The findings are discussed in relation to recent linguistic work on the representation of distributivity.

Humans↗

Achieving incremental semantic interpretation through contextual representation.

While much work has been done investigating the role of context in the incremental processing of syntactic indeterminacies, relatively little is known about online semantic interpretation. The experiments in this article made use of the eye-tracking paradigm with spoken language and visual contexts in order to examine how, and when listeners make use of contextually-defined contrast in interpreting simple prenominal adjectives. Experiment 1 focused on intersective adjectives. Experiment 1A provided further evidence that intersective adjectives are processed incrementally. Experiment 1B compared response times to follow instructions such as 'Pick up the blue comb' under conditions where there were two blue objects (e.g. a blue pen and a blue comb), but only one of these objects had a contrasting member in the display. Responses were faster to objects with a contrasting member, establishing that the listeners initially assume a contrastive interpretation for intersective adjectives. Experiments 2 and 3 focused on vague scalar adjectives examining the time course with which listeners establish contrast for scalar adjectives such as tall using information provided by the head noun (e.g. glass) and information provided by the visual context. Use of head-based information was examined by manipulating the typicality of the target object (e.g. whether it was a good or poor example of a tall glass. Use of context-dependent contrast was examined by either having only a single glass in the display (the no contrast condition) or a contrasting object (e.g. a smaller glass). The pattern of results indicated that listeners interpreted the scalar adjective incrementally taking into account context-specific contrast prior to encountering the head. Moreover, the presence of a contrasting object, sharply reduced, and in some conditions completely eliminated, typicality effects. The results suggest a language processing system in which semantic interpretation, as well as syntactic processing, is conducted incrementally, with early integration of contextual information.

Adult↗

The semantic interference effect in the picture-word interference paradigm: does the response set matter?

In three picture-word interference experiments we explore some properties of the semantic interference (SI) effect in the picture-word interference paradigm. In Experiments 1 and 2, we test whether SI may be obtained when the distractor words are not part of the response set and when only one picture per semantic category is included in the experiment. In Experiment 3, we explore if the magnitude of the SI effect depends on whether or not the distractor words are part of the response set. Reliable SI effects were obtained in all three experiments and the magnitude of the effect did not vary as a function of whether or not distractor words are part of the response set. These results are problematic for the selection mechanism in the WEAVER++ lexical access model (Levelt, W. J. M., Roelofs, A., & Meyer, A. S. (1999). A theory of lexical access in speech production. Behavioral and Brain Sciences. 22, 1-75; Roelofs, A. (1992). A spreading-activation theory of lemma retrieval in speaking. Cognition, 42, 107-142).

Humans↗