A left parietal infarct in a prelingually deaf person resulted in an aphasia for both American Sign Language (ASL) and written and finger-spelled English. Originally the patient had a nearly global aphasia affecting all language systems.... more
A left parietal infarct in a prelingually deaf person resulted in an aphasia for both American Sign Language (ASL) and written and finger-spelled English. Originally the patient had a nearly global aphasia affecting all language systems. By five to seven weeks post-onset her symptoms resembled those of hearing aphasics with posterior lesions: fluent but paraphasic signing, anomia, impaired comprehension and repetition, alexia, and agraphia with elements of neologistic jargon. In addition, there was a pronounced sequential movement copying disorder, reduced short-term verbal memory and acalculia. In general, the patient's sign errors showed a consistent disruption in the structure of ASL signs which parallels the speech errors of oral aphasic patients. We conclude that most aphasic symptoms are not modality-dependent, but rather reflect a disruption of linguistic processes common to all human languages. This case confirms the importance of the left hemisphere in the processing of sign language. Furthermore, the results indicate that the left supramarginal and angular gyri are necessary substrates for the comprehension of visual/gestural languages.
PMID: 7066673 [PubMed - indexed for MEDLINE]
PMID: 7066673 [PubMed - indexed for MEDLINE]
Research Interests:
Identifying the information processing constraints that determine whether or not imagery moderates visual field asymmetries is essential for constructing a dynamic model of hemispheric interaction during language processing. In this... more
Identifying the information processing constraints that determine whether or not imagery moderates visual field asymmetries is essential for constructing a dynamic model of hemispheric interaction during language processing. In this investigation, we manipulated the global experimental context in which imageable and nonimageable words were presented by contrasting mixed and blocked word lists using a lateralized lexical decision task. Signal detection analyses were employed to assess whether global stimulus context and imageability differentially affect word discriminability (d prime) and response bias (log beta) across visual fields. Both discriminability and response bias varied with imageability and stimulus context, but to a comparable extent across visual fields. This suggests that both hemispheres are sensitive to the global context in which words are presented, and can adjust processing based not only on semantic characteristics of the words themselves, but also on the variability of items in the stimulus environment.
Research Interests:
Previous research involving patients with brain damage, children with ADHD, aging adults, Alzheimer’s patients, and normal monolingual children and adults suggests that cortical thickness in certain regions of the brain, specifically the... more
Previous research involving patients with brain damage, children with ADHD, aging adults, Alzheimer’s patients, and normal monolingual children and adults suggests that cortical thickness in certain regions of the brain, specifically the dorsolateral prefrontal cortex, anterior cingulate cortex, inferior parietal lobule, and inferior frontal gyrus, is related to cognitive control abilities. In general, greater cortical thickness in these regions is associated with better cognitive control, and lesser cortical thickness is associated with poorer cognitive control. Surprisingly, researchers have not yet examined this relationship within the bilingual population, although bilinguals may have enhanced cognitive control abilities. Additionally, previous research suggests that greater grey matter density in one of these regions, the inferior parietal lobule, is greater for bilinguals than monolinguals, and is related to earlier age of second language acquisition, higher second language pr...
Adult age differences in automatic and controlled semantic priming were investigated by varying the probability of valid primes in a lexical decision task. Tachistoscopic parafoveal stimulus presentation was used to assess age differences... more
Adult age differences in automatic and controlled semantic priming were investigated by varying the probability of valid primes in a lexical decision task. Tachistoscopic parafoveal stimulus presentation was used to assess age differences in accuracy and response bias as well as latency. Both age groups showed the expected findings of benefits without costs under automatic priming and benefits and costs under controlled priming. Errors for young adults were distributed equally among word and nonword stimuli, whereas older adults displayed a strong tendency to commit errors on nonword trials.
Research Interests: Semantics, Gerontology, Cognition, Visual perception, Aging, and 8 moreAdolescent, Methods, Humans, Female, Male, Reaction Time, Aged, and Adult
Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical... more
Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical associates such as arm-leg) were employed in a low relatedness proportion lexical decision priming paradigm. A range of prime-target stimulus onset asynchronies (SOAs: 150-800 ms) was included. Only very weak evidence was obtained for a LVF priming lag at the briefest SOA, while priming was bilateral at moderately long SOAs. We consider these data in the context of previous time-course studies and suggest that, when highly semantically similar word pairs are used, a right hemisphere priming lag is, at best, a very small effect.
Research Interests:
... phonological decoding, recognition on the basis of the word's form, or semantic access (Balota & Chumbley ... proposed to rely on some form of compensation (Holmes & Standish, 1996; Jackson & Doellinger ... 60 cm in... more
... phonological decoding, recognition on the basis of the word's form, or semantic access (Balota & Chumbley ... proposed to rely on some form of compensation (Holmes & Standish, 1996; Jackson & Doellinger ... 60 cm in front of the monitor, using a headrest to stabilize head position. ...
Research Interests:
Previous results (Burgess & Simpson, 1988a) have suggested that subordinate meanings are activated in the right hemisphere only when they have been inhibited in the left hemisphere. Such findings are consistent with a homotopic... more
Previous results (Burgess & Simpson, 1988a) have suggested that subordinate meanings are activated in the right hemisphere only when they have been inhibited in the left hemisphere. Such findings are consistent with a homotopic callosal inhibition view of hemispheric interaction (Cook, 1986). The current study employed prime-target stimulus onset asynchronies intermediate to those used by Burgess and Simpson and obtained equivalent priming of subordinate meanings over visual fields. These data rule out homotopic callosal inhibition as the mechanism responsible for initial activation of subordinate meanings in the right hemisphere and challenge homotopic inhibition as a general mechanism of interhemispheric interaction.
Research Interests:
Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit... more
Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit (cued recall) tasks; only the intention to recall list words differed. The young adults outperformed the older adults on both implicit and explicit tasks at all test delays. Under some conditions, the older but not the young adults performed more poorly on cued recall than on stem completion, suggesting a possible failure to use implicitly available information to support explicit remembering. These results suggest that some forms of implicit memory decline with normal aging.
Research Interests:
Research Interests:
The current investigation tested 20 male right-handers in 5 divided visual field lexical tasks. Asymmetries in Heschl's gyrus, planum temporale, and planum parietale were measured using structural magnetic resonance... more
The current investigation tested 20 male right-handers in 5 divided visual field lexical tasks. Asymmetries in Heschl's gyrus, planum temporale, and planum parietale were measured using structural magnetic resonance imaging. Composite task asymmetries were positively correlated with asymmetry of the planum temporale only. There was also an association between the consistency of anatomical and behavioral asymmetries: Individuals who departed the most from the modal pattern of cortical asymmetry across regions also tended to show the greatest variability in asymmetry across tasks. Hence, individual differences in language laterality tasks may be affected by variation in asymmetry of posterior language structures. Additionally, when typical anatomical asymmetries fail to co-occur, there may be a less strictly regulated distribution of function across hemispheres.
Research Interests:
To support categorical representation in the brain for grammatical class, it is necessary to show that noun-verb differences are attributable to parts of speech and not to covarying semantic factors. Prior visual-half field investigations... more
To support categorical representation in the brain for grammatical class, it is necessary to show that noun-verb differences are attributable to parts of speech and not to covarying semantic factors. Prior visual-half field investigations of noun-verb processing have confounded grammatical class with imageability. The current study included numerous tests of differential noun-verb processing across visual fields for stimuli equated for imageability. Task (lexical decision, pronunciation) and list context (blocked vs. mixed lists) variables were examined in 168 right-handed participants. There was no reliable reduction of the right visual field advantage for moderately imageable nouns as compared with verbs. If there are qualitative hemisphere differences in single-word noun and verb recognition, these may be attributable to semantic dimensions that tend to covary with grammatical class.
Research Interests: Psychology, Neuropsychology, Cognition, Vocabulary, Linguistics, and 7 moreBrain, Humans, Female, Male, Reaction Time, Adult, and Neurosciences
Research Interests: Psychology, Neuropsychology, Phonetics, Semantics, Magnetic Resonance Imaging, and 19 morePrefrontal Cortex, Semantic relations, Brain Mapping, Right Hemisphere Functions, Humans, Cerebral Cortex, Female, Male, Reaction Time, Semantic Priming, Arousal, Adult, Semantic retrieval, Visual Fields, Left Hemisphere, Visual Field, Neurosciences, Time Course, and Verbal Learning
Page 1. Neuropsychology 1998, Vol. 12, No. 1,78-94 Copyright 1998 by the American Psychological Association, Inc. 0894-4105/98/$3.00 Bihemispheric Processing of Redundant Bilateral Lexical Information Ronald E. Hasbrooke ...
Research Interests:
A lexical decision experiment investigated hemisphere asymmetries in resolving lexical ambiguity within a sentence context. Sentences that biased a single meaning (either dominant or subordinate) of sentence-final ambiguous words were... more
A lexical decision experiment investigated hemisphere asymmetries in resolving lexical ambiguity within a sentence context. Sentences that biased a single meaning (either dominant or subordinate) of sentence-final ambiguous words were followed by a lateralized target related to the sentence-congruent or -incongruent meaning of the ambiguous word, or an unrelated word. In the RVF sentence-congruent targets were facilitated, while incongruent targets were not primed. In contrast, related targets were facilitated in the LVF, regardless of sentence context. This suggests that selecting the contextually appropriate word meaning requires the left hemisphere, and supports a right hemisphere role in maintaining alternate word senses.
Research Interests: Psychology, Cognitive Science, Semantics, Reading, Right Hemisphere Functions, and 15 moreHumans, Cerebral Cortex, Cues, Female, Male, Reaction Time, Lexical Decision, Hemispheric Asymmetry, Ambiguity Resolution, Adult, Analysis of Variance, Neuropsychologia, Visual Fields, Left Hemisphere, and Neurosciences
This study investigated cerebral asymmetries in sensitivity to sentence-level semantic anomaly. To separate the effects of anomalous message processing from those attributable to low sentence constraint, low-constraint sentence-fragment... more
This study investigated cerebral asymmetries in sensitivity to sentence-level semantic anomaly. To separate the effects of anomalous message processing from those attributable to low sentence constraint, low-constraint sentence-fragment primes were followed by target words presented to the left or right visual fields. When completed by the target word, the sentences represented either normal or anomalous messages; in addition, one-half of the sentence primes contained a word strongly related to the target. Targets presented to both the left and right visual fields were advantaged by the presence of a related word, and disadvantaged by the presence of a semantically anomalous message. Contrary to some previous claims, this result implies that the right hemisphere can construct some message-level interpretations from sentences, such that semantic anomaly is registered, even if finer gradations of sentence constraint are not. This rudimentary integration of word meanings in sentences may provide a scaffolding for right hemisphere discourse processing. In light of these findings, we propose a revised view of left/right hemisphere differences in the processes used to interpret sentence meaning.
Research Interests: Psychology, Cognitive Science, Semantics, Humans, Cues, and 6 moreFemale, Male, Adult, Neuropsychologia, Visual Fields, and Neurosciences
This study investigated the depth of associative activation in the cerebral hemispheres. Semantic priming was assessed for direct (WATER-DRINK) and indirect (mediated: SOAP-DRINK) associates presented to the left and right visual fields... more
This study investigated the depth of associative activation in the cerebral hemispheres. Semantic priming was assessed for direct (WATER-DRINK) and indirect (mediated: SOAP-DRINK) associates presented to the left and right visual fields across stimulus-onset-asychronies (SOAs) of 50, 250 and 750 msec. Priming for both the direct and indirect associates was found in both visual fields at all SOAs. Our results imply that activation via associated relations in semantic memory is early and extensive in both hemispheres. We relate our findings to the previous suggestion [5, 9, 14] that meaning activation is more narrow in the left hemisphere (LH) than in the right hemisphere (RH).
Research Interests:
We report test-retest reliabilities and individual asymmetries for a lateralized lexical decision task. Although acceptable reliability was found for word recognition, most subjects did not show statistically significant asymmetries,... more
We report test-retest reliabilities and individual asymmetries for a lateralized lexical decision task. Although acceptable reliability was found for word recognition, most subjects did not show statistically significant asymmetries, despite a robust right visual field group advantage. Inter-subject variability was unrelated to sex, handedness, or familial sinistrality. We offer some suggestions as to why these differences are to be expected in the study of normal populations.
Research Interests:
ABSTRACT Exposure duration, retinal eccentricity and stimulus size were systematically varied to assess the contribution of viewing conditions to the lexical decision asymmetry. Contrary to Sergent's hypothesis (Psychol. Bull. 93,... more
ABSTRACT Exposure duration, retinal eccentricity and stimulus size were systematically varied to assess the contribution of viewing conditions to the lexical decision asymmetry. Contrary to Sergent's hypothesis (Psychol. Bull. 93, 481-512), the RVF advantage was unaltered over the range of conditions tested. This suggests that hemisphere differences in the ability to extract information from degraded signals cannot account for the asymmetry in this task. The results are compatible with the view that the lexical decision asymmetry arises from a relatively late stage of processing in which the information is no longer represented in sensory form.
Research Interests:
This study investigated the processing of content and function words when input to the left vs right hemispheres. For both lexical decision and naming there was a larger RVF advantage for function as compared to content words: function... more
This study investigated the processing of content and function words when input to the left vs right hemispheres. For both lexical decision and naming there was a larger RVF advantage for function as compared to content words: function words were processed more slowly than content in the LVF, but not in the RVF. These results do not replicate the previous report of Bradley and Garrett, Neuropsychologia 21, 155-159, 1983, and provide some support for the view that function words are less accessible to the right hemisphere. In a second experiment, there was no difference in VF asymmetry when acceptability judgments were required for function vs content word phrases. Grammaticality judgments, of any sort, may be predominantly processed in the left hemisphere.
Research Interests:
This study investigated the effect of exemplar dominance on semantic priming in the left and right visual fields for words that are members of the same category, but not strongly associated. A low proportion of related primes was employed... more
This study investigated the effect of exemplar dominance on semantic priming in the left and right visual fields for words that are members of the same category, but not strongly associated. A low proportion of related primes was employed in lexical decision and word pronunciation tasks to assess the automatic activation of word meanings in each cerebral hemisphere. Priming was reliably obtained only in the LVF/right hemisphere. In addition, this effect did not vary with category dominance of the prime:equivalent LVF priming was observed for ROBIN-CROW (high dominant) and DUCK-CROW (low dominant) pairs. These findings support the view that a broader range of related meanings is activated during word recognition in the right, than in the left, hemisphere.
Research Interests:
Research Interests:
... Although this article has focused on issues in metaphor and idiom com-prehension, similar issues are present for other types of figurative ... McDonald & Wales, 1986; Tomp-kins & Mateer, 1985), comprehension of humor... more
... Although this article has focused on issues in metaphor and idiom com-prehension, similar issues are present for other types of figurative ... McDonald & Wales, 1986; Tomp-kins & Mateer, 1985), comprehension of humor (Bihrle et al., 1986; Gardner, Ling, Flamrn, & Silverman ...
Research Interests:
In a divided-visual-field priming paradigm, participants made manual lexical decisions performing either go no-go responses, or yes-no responses, to related prime-target word pairs that were nonassociated, category members (DEER-PONY).... more
In a divided-visual-field priming paradigm, participants made manual lexical decisions performing either go no-go responses, or yes-no responses, to related prime-target word pairs that were nonassociated, category members (DEER-PONY). Half of each response group received unrelated (ATTIC-PONY) baselines and half received neutral (BLANK-PONY) baselines. In the go no-go response, small but reliable priming was obtained in both target visual fields and there was a reliable slowing of response time in the right visual field/left hemisphere for participants receiving the neutral baseline. In the yes-no response, greater priming was obtained from a neutral baseline, as compared to an unrelated baseline. We show that under appropriate conditions priming for these stimuli occurs in both visual fields. We also report that cross-visual-field advantages emerged as cognitive task load increased across combinations of baseline and response variables. We conclude that task load may be as important a factor in priming asymmetries as SOA or type of semantic relationship.
Research Interests:
This study investigated hemisphere differences in sensitivity to orthographic and phonological similarity using a task that did not require deliberate metalinguistic comparisons between words. Two experiments investigated the influence of... more
This study investigated hemisphere differences in sensitivity to orthographic and phonological similarity using a task that did not require deliberate metalinguistic comparisons between words. Two experiments investigated the influence of an unattended distractor item on the pronunciation of target words in the right visual field (RVF) and left visual field (LVF) in neurologically intact persons. Word and pseudoword distractors that were both orthographically and phonologically similar to the target word produced equivalent facilitation across visual fields (Exp. 1). When orthographic and phonological influences were separated in Exp. 2, each dimension produced reliable facilitation, and to the same extent in each visual field. These results, and others in the literature, are difficult to reconcile with the view that the intact right hemisphere is completely unable to access phonology from print. If subsequent research confirms these findings, it would suggest that passive activation of phonology in reading can be dissociated from articulatory mechanisms, and that left hemisphere superiority in some phonological judgements may depend more on the availability of articulatory rehearsal than on privileged access to phonological codes.
Research Interests:
Individual differences in reading and cerebral lateralisation were investigated in 200 college students who completed reading assessments and divided visual field word recognition tasks, and received a structural MRI scan. Prior studies... more
Individual differences in reading and cerebral lateralisation were investigated in 200 college students who completed reading assessments and divided visual field word recognition tasks, and received a structural MRI scan. Prior studies on this data set indicated that little variance in brain-behaviour correlations could be attributed to the effects of sex and handedness variables (Chiarello, Welcome, Halderman, & Leonard, 2009; Chiarello, Welcome, Halderman, Towler, et al., 2009; Welcome et al., 2009). Here a more bottom-up approach to behavioural classification (cluster analysis) was used to explore individual differences that need not depend on a priori decisions about relevant subgroups. The cluster solution identified four subgroups of college age readers with differing reading skill and visual field lateralisation profiles. These findings generalised to measures that were not included in the cluster analysis. Poorer reading skill was associated with somewhat reduced VF asymmetry, while average readers demonstrated exaggerated RVF/left hemisphere advantages. Skilled readers had either reduced asymmetries, or asymmetries that varied by task. The clusters did not differ by sex or handedness, suggesting that there are identifiable sources of variance among individuals that are not captured by these standard participant variables. All clusters had typical leftward asymmetry of the planum temporale. However, the size of areas in the posterior corpus callosum distinguished the two subgroups with high reading skill. A total of 17 participants, identified as multivariate outliers, had unusual behavioural profiles and differed from the remainder of the sample in not having significant leftward asymmetry of the planum temporale. A less buffered type of neurodevelopment that is more open to the effects of random genetic and environmental influences may characterise such individuals.
Research Interests: Genetics, Psychology, Cognitive Science, Individuality, Magnetic Resonance Imaging, and 19 moreReading, Laterality, Face recognition (Psychology), Language, Brain Mapping, Humans, Corpus Callosum, Cerebral Cortex, Word Recognition, Female, College Students, Male, Cluster Analysis, Adult, Visual Fields, Left Hemisphere, Bottom Up, Visual Field, and Individual Difference
Research Interests:
Horizontal and vertical stings were presented in a "crosswords" format within left or right visual fields. Distractor strings were varied to examine the extent to which prelexical, orthographic-phonological, and semantic... more
Horizontal and vertical stings were presented in a "crosswords" format within left or right visual fields. Distractor strings were varied to examine the extent to which prelexical, orthographic-phonological, and semantic codes are activated for words not focally attended. The results supported 2 predictions of the pathway strength model of attentional modulation (JD Cohen, K Dunbar & JL McClelland, 1990). First, distractor influences were greater when participants attended to the weaker (ie, vertical) item and ignored the stronger (ie, horizontal) string, than vice versa. Second, distractors similar to the target facilitated, whereas dissimilar distractors interfered with, pronunciation responses. It is concluded that spatial attention can modulate word recognition processes, and that some interesting questions emerge when one abandons the assumptions of serial, noninteractive word recognition processes.
Research Interests:
The authors report findings of a large-scale, multitask investigation of sex differences in both structural asymmetries and lateralization of word reading. Two hundred participants were tested in eight divided visual field lexical tasks,... more
The authors report findings of a large-scale, multitask investigation of sex differences in both structural asymmetries and lateralization of word reading. Two hundred participants were tested in eight divided visual field lexical tasks, and each received a structural magnetic resonance imaging scan. The authors examined whether there was evidence for sex differences in overall measures of neuroanatomical and behavioral lateralization, in specific language tasks and brain regions, and in variation in asymmetry within and across tasks and brain regions. There was very little evidence for sex differences on any behavioral measure. The few indications of sex differences in the current report accounted for 2% or less of the individual variation in asymmetry and could not be replicated in independent subsamples. No sex differences were observed in the asymmetry of structures in Broca's and Wernicke's areas such as pars triangularis, pars opercularis, the planum temporale, planu...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
This study investigated spreading activation for words presented to the left and right hemispheres using an automatic semantic priming paradigm. Three types of semantic relations were used: similar-only (Deer-Pony), associated-only... more
This study investigated spreading activation for words presented to the left and right hemispheres using an automatic semantic priming paradigm. Three types of semantic relations were used: similar-only (Deer-Pony), associated-only (Bee-Honey), and similar + associated (Doctor-Nurse). Priming of lexical decisions was symmetrical over visual fields for all semantic relations when prime words were centrally presented. However, when primes and targets were lateralized to the same visual field, similar-only priming was greater in the LVF than in the RVF, no priming was obtained for associated-only words, and priming was equivalent over visual fields for similar + associated words. Similar results were found using a naming task. These findings suggest that it is important to lateralize both prime and target information to assess hemisphere-specific spreading activation processes. Further, while spreading activation occurs in either hemisphere for the most highly related words (those related by category membership and association), our findings suggest that automatic access to semantic category relatedness occurs primarily in the right cerebral hemisphere. These results imply a unique role for the right hemisphere in the processing of word meanings. We relate our results to our previous proposal (Burgess & Simpson, 1988a; Chiarello, 1988c) that there is rapid selection of one meaning and suppression of other candidates in the left hemisphere, while activation spreads more diffusely in the right hemisphere. We also outline a new proposal that activation spreads in a different manner for associated words than for words related by semantic similarity.
Research Interests:
We investigated whether abstract and concrete words would be differentially effective in priming lexical decisions to words presented to the right and left visual fields. Under low probability prime conditions, where priming is presumed... more
We investigated whether abstract and concrete words would be differentially effective in priming lexical decisions to words presented to the right and left visual fields. Under low probability prime conditions, where priming is presumed to reflect a spreading activation process within the lexicon, equivalent priming was obtained in each VF for both abstract and concrete primes. However, when the same words were used in a high probability prime paradigm, abstract primes were much less effective in the LVF than in the RVF, while priming with concrete words did not differ across the visual fields. Since such priming may reflect a postlexical semantic integration stage, the results imply that hemisphere differences for processing abstract and concrete words may arise only after lexical access has occurred, when semantic information retrieved from the lexicon becomes available for subsequent processing.
Research Interests: Semantics, Humans, Concept Formation, Female, Male, and 3 moreReaction Time, Semantic Priming, and Adult
Two divided visual field priming experiments examined cerebral asymmetries for understanding metaphors varying in sentence constraint. Experiment 1 investigated ambiguous words (e.g., SWEET and BRIGHT) with literal and metaphoric meanings... more
Two divided visual field priming experiments examined cerebral asymmetries for understanding metaphors varying in sentence constraint. Experiment 1 investigated ambiguous words (e.g., SWEET and BRIGHT) with literal and metaphoric meanings in ambiguous and unambiguous sentence contexts, while Experiment 2 involved standard metaphors (e.g., The drink you gave me was a meteor) with sententially consistent and inconsistent targets (i.e., POTENT vs COMET). Similar literal and metaphor priming effects were found in both visual fields across most experimental conditions. However, RH processes also maintained activation of sententially inconsistent literal meanings following metaphoric expressions. These results do not strongly support the RH as the preferred substrate for metaphor comprehension (e.g., ), and suggest that processes in both hemispheres can support metaphor comprehension, although not via identical mechanisms. The LH may utilize sentence constraint to select and integrate only contextually relevant literal and metaphoric meanings, whereas the RH may be less sensitive to sentence context and can maintain the activation of some alternative interpretations. This may be potentially useful in situations where an initial understanding must be revised.
Research Interests:
The current experiment investigated how sentential form-class expectancies influenced lexical-semantic priming within each hemisphere. Sentences were presented that led readers to expect a noun or a verb and the sentence-final target word... more
The current experiment investigated how sentential form-class expectancies influenced lexical-semantic priming within each hemisphere. Sentences were presented that led readers to expect a noun or a verb and the sentence-final target word was presented to one visual field/hemisphere for a lexical decision response. Noun and verb targets in the semantically related condition were compared to an unrelated prime condition, which also predicted part of speech but did not contain any lexical-semantic associates of the target word. The semantic priming effect was strongly modulated by form-class expectancy for RVF/LH targets, for both nouns and verbs. In the LVF/RH, semantic priming was obtained in all conditions, regardless of whether the form-class expectancy was violated. However, the nouns that were preceded by a noun-predicting sentence showed an extremely high priming value in the LVF/RH, suggesting that the RH may have some sensitivity to grammatical predictions for nouns. Comparisons of LVF/RH priming to calculations derived from the LSA model of language representation, which does not utilize word order, suggested that the RH might derive message-level meaning primarily from lexical-semantic relatedness.
Research Interests: Semantics, Vocabulary, Linguistics, Brain, Humans, and 8 moreCues, Female, Male, Lexical Decision, Semantic Priming, Adult, Visual Fields, and Part of Speech
Because language and praxis each require the activation and selection of knowledge structures in long-term memory (MacKay, 1985, 1987), it is reasonable to consider whether hemisphere asymmetries for such processes span both domains.... more
Because language and praxis each require the activation and selection of knowledge structures in long-term memory (MacKay, 1985, 1987), it is reasonable to consider whether hemisphere asymmetries for such processes span both domains. Language and skilled movement are thought to be strongly lateralized to the left hemisphere in most individuals. Yet, although recent evidence suggests that the right hemisphere also contributes to language use in context, few similar arguments have been made for the right hemisphere's involvement in motor planning. In this paper, we review some of the evidence for a right hemisphere role in language and action processing and propose that within each domain the right hemisphere activates a range of relevant knowledge structures without selection.
Research Interests:
Research Interests:
Research Interests:
Individual differences in cortical anatomy are readily observable, but their functional significance for behaviors such as reading is not well understood. Here, we report a case of an apparent compensated dyslexic who had attained high... more
Individual differences in cortical anatomy are readily observable, but their functional significance for behaviors such as reading is not well understood. Here, we report a case of an apparent compensated dyslexic who had attained high achievement in visuospatial mathematics. Data from a detailed background interview, psychometric testing, divided visual field tasks measuring basic word recognition (word naming, nonword naming, and lexical decision), and more controlled word retrieval (verb, category, and rhyme generation), and measurements of his atypical brain structure are described. The findings suggested that enhanced "top-down" processing could provide the means to compensate for deficient "bottom-up" word decoding skills in this case. Relative to controls, this individual also evidenced unusually large asymmetries on several divided visual field lexical tasks, an extreme leftward asymmetry of the planum temporale, and a rare form of Sylvian fissure morphology (Steinmetz type 4, [Steinmetz, H., Ebeling, U., Huang, Y., & Kahn, T. (1990). Sulcus topography of the parietal opercular region: An anatomic and MR study. Brain and Language, 38, 515-533.]). We suggest that certain forms of brain organization may be associated with successful behavioral compensation for dyslexia, and that anatomical variations in the right hemisphere may be important contributors to individual differences in reading acquisition and achievement.
Research Interests:
Signal detection measures were used to evaluate the effects of several response variables (manual vs. vocal, Go-NoGo vs. Yes-No) on lexical decision asymmetries. An unvarying right visual field advantage in discriminability (d')... more
Signal detection measures were used to evaluate the effects of several response variables (manual vs. vocal, Go-NoGo vs. Yes-No) on lexical decision asymmetries. An unvarying right visual field advantage in discriminability (d') was observed in each condition. However, response criteria (beta) varied over visual fields and conditions. Naming and lexical decision were shown to have equivalent asymmetries when the effects of response bias are removed. The results indicate that postaccess decision processes make important contributions to lexical decision asymmetries.
Research Interests:
In this article we examine whether the distribution of function across the right and left cerebral hemispheres for lexical processing is influenced by the global context within which words are presented. A review of previously published... more
In this article we examine whether the distribution of function across the right and left cerebral hemispheres for lexical processing is influenced by the global context within which words are presented. A review of previously published studies indicates that the ubiquitous right visual field (RVF)/left hemisphere advantage for word recognition may be reduced or eliminated for nouns, content words, or high image words, but only when such items are presented along with verbs, function words, or low image words. However, paradoxically, when the former items are presented in more homogeneous contexts, the RVF advantage is uniformly observed. We propose that the processing efficiency of a hemisphere for a given stimulus depends on that item's relation to the other stimuli provided, that is, the global context. This was examined in a visual half-field experiment that varied whether high and low image nouns were presented in homogeneous (blocked lists) or heterogeneous (mixed lists) contexts. An unvarying RVF advantage was observed for high image words in homogeneous contexts, but this advantage was eliminated when the same items were presented in heterogeneous contexts. We suggest that stimulus heterogeneity maximizes reliance on differing, but complementary, computational biases across hemispheres. Hence, the extent to which the left and right hemispheres are recruited for the recognition of individual word types can vary dynamically with variation in the stimulus environment.
Research Interests: Cognition, Vocabulary, Imagination, Brain, Humans, and 7 moreFemale, Male, Reaction Time, Questionnaires, Adult, Visual Fields, and Environment
We report the results of two visual half-field semantic priming experiments using a high proportion of related trials to examine hemisphere asymmetries for semantic processes beyond those attributable to automatic meaning activation.... more
We report the results of two visual half-field semantic priming experiments using a high proportion of related trials to examine hemisphere asymmetries for semantic processes beyond those attributable to automatic meaning activation. Contrary to previous investigations, we obtained inhibition for unrelated trials in both visual fields. However, priming was additive (being greater for words related via category membership and association than for either single dimension) only when words were presented to the RVF/left hemisphere. A third experiment, using centrally presented stimuli, implied that semantic additivity should be attributed to post-access meaning comparisons and inhibition to the generation of semantic expectancies. These results suggest (1) that inhibition and additivity are potentially dissociable "controlled" semantic processes and (2) that the left hemisphere predominates for meaning integration across successively presented words. The availability of finely tuned meaning integration processes in the left hemisphere may contribute to its superiority in language processing, despite right hemisphere competence for some semantic operations.
Research Interests: Semantics, Psycholinguistics, Speech perception, Attention, Reading, and 5 moreHumans, Female, Male, Reaction Time, and Adult
Hemisphere differences in lexical processing may be due to asymmetry in the organization of lexical information, in procedures used to access the lexicon, or both. Six lateralized lexical decision experiments employed various types of... more
Hemisphere differences in lexical processing may be due to asymmetry in the organization of lexical information, in procedures used to access the lexicon, or both. Six lateralized lexical decision experiments employed various types of priming to distinguish among these possibilities. In three controlled (high probability) priming experiments, prime words could be used as lexical access clues. Larger priming was obtained for orthographically similar stimuli (BEAK-BEAR) when presented to the left visual field (LVF). Controlled priming based on phonological relatedness (JUICE-MOOSE) was equally effective in either visual field (VF). Semantic similarity (INCH-YARD) produced larger priming for right visual field (RVF) stimuli. These results suggest that the hemispheres may utilize different information to achieve lexical access. Spread of activation through the lexicon was measured in complementary automatic (low probability) priming experiments. Priming was restricted to LVF stimuli for orthographically similar words, while priming for phonologically related stimuli was only obtained in the RVF. Automatic semantic priming was present bilaterally, but was larger in the LVF. These results imply hemisphere differences in lexical organization, with orthographic and semantic relationships available to the right hemisphere, and phonological and semantic relations available to the left hemisphere. Support was obtained for hemisphere asymmetries in both lexical organization and directed lexical processing.
Research Interests: Phonetics, Semantics, Visual perception, Reading, Adolescent, and 8 moreHumans, Female, Male, Reaction Time, Lexical access, Adult, Visual Fields, and Syndrome
The present study examined left (LH) and right (RH) hemisphere involvement in discourse processing by testing the ability of each hemisphere to use world knowledge in the form of script contexts for word recognition. Participants made... more
The present study examined left (LH) and right (RH) hemisphere involvement in discourse processing by testing the ability of each hemisphere to use world knowledge in the form of script contexts for word recognition. Participants made lexical decisions to laterally presented target words preceded by centrally presented script primes (four sentences describing common situations). To examine the maintenance of script information across intervening text, there were six types of primes. These consisted of either single scripts or combinations of two different scripts: (1) a related script, (2) an unrelated script, (3) a related script+a neutral "filler," (4) a related script+an unrelated script, (5) an unrelated script+a related script, and (6) a neutral baseline condition. Results indicated that in the LH, only related scripts or related scripts preceded by unrelated scripts facilitated target word recognition. In contrast, the RH gained significant facilitation from all combinations of script primes, including related scripts followed by either filler materials or unrelated scripts. These results are consistent with the theory that the RH contributes in a critical way to discourse comprehension by maintaining widespread meaning activation for an extended period. This unique ability of the RH may be especially important for integrative processes needed to achieve global coherence during discourse processing.