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PubMed2003

A magnetic stimulation examination of orthographic neighborhood effects in visual word recognition.

The split-fovea theory proposes that visual word recognition is mediated by the splitting of the foveal image, with letters to the left of fixation projected to the right hemisphere (RH) and letters to the right of fixation projected to the left hemisphere (LH). We applied repetitive transcranial magnetic stimulation (rTMS) over the left and right occipital cortex during a lexical decision task to investigate the extent to which word recognition processes could be accounted for according to the split-fovea theory. Unilateral rTMS significantly impaired lexical decision latencies to centrally presented words, supporting the suggestion that foveal representation of words is split between the cerebral hemispheres rather than bilateral. Behaviorally, we showed that words that have many orthographic neighbors sharing the same initial letters ("lead neighbors") facilitated lexical decision more than words with few lead neighbors. This effect did not apply to end neighbors (orthographic neighbors sharing the same final letters). Crucially, rTMS over the RH impaired lead-, but not end-neighborhood facilitation. The results support the split-fovea theory, where the RH has primacy in representing lead neighbors of a written word.

Adult↗
PubMed2001

Speech recognition software.

This article discusses the use of speech recognition software by means of reviewing two leading packages. Both programs require considerable training before they can be used effectively, but are then able to convert continuous speech into text with varying degrees of success.

CD-ROM↗
PubMed1997

CPRs that cure.

Explore the source record for details and available documents.

Cost-Benefit Analysis↗
PubMed2001

The time-limited influence of sentential context on function word identification.

Sentential context effects on the identification of the Dutch function words te (to) and de (the) were examined. In Experiment 1, listeners labeled words on a [t inverted e]-[d inverted e] continuum more often as te when the context waste biased (Ik probeer [? inverted e] schieten [I try to/the shoot]) than when it was de biased (Ik probeer [? inverted e] schoenen [I try to/the shoes]). The effect was weaker in slower responses. In Experiment 2, disambiguation began later, in the second word after [? inverted e]. There was a weak context effect only in the slower responses. In Experiments 3 and 4, disambiguation occurred on the word before [? inverted e]: There was no context effect when one set of sentences was used, but there was an effect (larger in the faster responses) when more sentences were used. Syntactic processing affects word identification only within a limited time frame. It appears to do so not by influencing lexical access processes through feedback but, instead, by biasing decision making.

Feedback↗
PubMed1988

Effects of lateralized presentation on levels of processing in memory.

The present study utilized lateralized presentation of words in a level-of-processing paradigm. Eighty words were presented to subjects in four level-of-processing conditions: orthographic, phonetic, syntactic and semantic. Words were presented either to the left or right visual fields (Experiments 1 and 2), or centrally (Experiment 3). Both free recall and recognition retrieval conditions were utilized. There were no visual field differences in the recognition condition. In the free recall condition, there was an interaction between visual field of presentation and level of processing. Recall was greatest for phonetically and semantically processed words which had been presented to the right visual field. A left visual field advantage was found for syntactically processed words. Results are interpreted in the context of retrieval strategies and hemisphere-linked processing capacities.

Functional Laterality↗
PubMed2005

Interpretation of orthographic uniqueness point effects in visual word recognition.

The orthographic uniqueness point (OUP) of a word is the position of the first letter from the left that distinguishes a word from all other words. In 2 recent studies (P. J. Kwantes & D. J. K. Mewhort, 1999a; A. K. Lindell, M. E. R. Nicholls, & A. E. Castles, 2003), it has been observed that words with an early OUP were processed more quickly than words with a late OUP. This has been taken to suggest that observers process the letters of words sequentially in a left-to-right order. In this article, it is shown that the OUP results do not provide selective evidence for left-to-right sequential processing in visual word recognition because the data are also compatible with an account in which letter processing occurs in random order.

Attention↗
PubMed1989

The properties of retrieval cues constrain the picture superiority effect.

In three experiments, we examined why pictures are remembered better than words on explicit memory tests like recall and recognition, whereas words produce more priming than pictures on some implicit tests, such as word-fragment and word-stem completion (e.g., completing -l-ph-nt or ele----- as elephant). One possibility is that pictures are always more accessible than words if subjects are given explicit retrieval instructions. An alternative possibility is that the properties of the retrieval cues themselves constrain the retrieval processes engaged; word fragments might induce data-driven (perceptually based) retrieval, which favors words regardless of the retrieval instructions. Experiment 1 demonstrated that words were remembered better than pictures on both the word-fragment and word-stem completion tasks under both implicit and explicit retrieval conditions. In Experiment 2, pictures were recalled better than words with semantically related extralist cues. In Experiment 3, when semantic cues were combined with word fragments, pictures and words were recalled equally well under explicit retrieval conditions, but words were superior to pictures under implicit instructions. Thus, the inherently data-limited properties of fragmented words limit their use in accessing conceptual codes. Overall, the results indicate that retrieval operations are largely determined by properties of the retrieval cues under both implicit and explicit retrieval conditions.

Adult↗
PubMed2002

Neuroimaging reveals automatic speech coding during perception of written word meaning.

The extent to which visual word perception engages speech codes (i.e., phonological recoding) remains a crucial question in understanding mechanisms of reading. In this study, we used functional magnetic resonance imaging techniques combined with behavioral response measures to examine neural responses to focused versus incidental phonological and semantic processing of written words. Three groups of subjects made simple button-pressing responses in either phonologically (rhyming-judgment) or semantically (category-judgment) focused tasks or both tasks with identical sets of visual stimuli. In the phonological tasks, subjects were given both words and pseudowords separated in different scan runs. The baseline task required feature search of scrambled letter strings created from the stimuli for the experimental conditions. The results showed that cortical regions associated with both semantic and phonological processes were strongly activated when the task required active processing of word meaning. However, when subjects were actively processing the speech sounds of the same set of written words, brain areas typically engaged in semantic processing became silent. In addition, subjects who performed both the rhyming and the semantic tasks showed diverse and significant bilateral activation in the prefrontal, temporal, and other brain regions. Taken together, the pattern of brain activity provides evidence of a neural basis supporting the theory that in normal word reading, phonological recoding is automatic and facilitates semantic processing of written words, while rapid comprehension of word meaning requires devoted attention. These results also raise questions about including multiple cognitive tasks in the same neuroimaging sessions.

Adult↗
PubMed1994

Semantic processing of pictures and spoken words: evidence from event-related brain potentials.

Semantic associations between pictures and their verbal referents were assessed in a reaction time (RT) experiment where pictures and words acted both as primes and targets. Behavioral RTs and accuracy were recorded from 20 adult subjects along with the event-related brain potentials (ERPs) recorded from two midline and 10 lateral electrode sites. Behavioral effects were inconclusive, but the ERPs to target stimuli varied as a function of whether the priming stimulus was semantically related or unrelated to the target. The ERPs elicited to unrelated picture targets and unrelated word targets were more negative than their related counterparts and fit the characteristics of the N400 during all but the initial phase of differential processing. The differences in scalp distribution in the initial phases appear to reflect the processing of nonidentical sensory-specific mechanisms; the common later peak activity reflects the processing of a single common semantic processor.

Adolescent↗
PubMed2004

A neural network model of lexicalization for simulating the anomic naming errors of dementia patients.

Word-finding difficulty (anomia) is the most common linguistic deficit in dementia. It is often measured by picture naming tasks as naming a picture taps all the major processes in word production, i.e., activation of a concept, retrieval of lexical-semantic information on that concept, retrieval of the corresponding word form and articulation. Naming and naming errors have extensively been simulated by neural network models of lexicalization (see e.g. [1,2]). A common feature of these models is that they are static, i.e. non-learning. However, naming is a dynamic process that changes as a function of normal learning or re-learning after neural damage. These important patterns cannot be caught by the static models of lexicalization. Therefore we have developed a learning model of lexicalization based on multi-layer-perceptron (MLP) neural networks. We tested the model by fitting it to the naming data of 22 Finnish-speaking dementia patients and 19 neurologically intact control subjects. The tests showed an excellent fit between the model's and the subjects naming response distributions. Thus our model seems be suitable to simulate naming disorders of dementia patients.

Alzheimer Disease↗
PubMed1983

Parafoveal words are effective in both hemifields: preattentive processing of semantic and phonological codes.

What effect may an unattended word have during a single fixation? Attention was selectively directed to a word exposed for 50 ms by the demand to make a rapid lexical decision response, and during the same presentation a second word was displayed approximately 2.3 deg of visual angle away on the same horizontal axis. The second word was backwards and forwards masked by a random-dot display, and was described to subjects as a distractor which was to be ignored. Although no response was required to this word, it was found to influence response latency to the attended word according to the semantic relationship which existed between the two. They interfered with the lexical decision response when the two words were related in meaning and also when they sounded as if they were related in meaning. These effects argue for automatic processing of the meaning of printed words presented in either visual hemifield, and for their automatic phonological activation.

Attention↗
PubMed2005

Neuroanatomical correlates of phonological processing of Chinese characters and alphabetic words: a meta-analysis.

We used the activation likelihood estimation (ALE) method to quantitatively synthesize data from 19 published brain mapping studies of phonological processing in reading, six with Chinese and 13 with alphabetic languages. It demonstrated high concordance of cortical activity across multiple studies in each written language system as well as significant differences of activation likelihood between languages. Four neural systems for the phonological processing of Chinese characters included: (1) a left dorsal lateral frontal system at Brodmann area (BA) 9; (2) the dorsal aspect of left inferior parietal system; (3) a bilateral ventral-occipitotemporal system including portions of fusiform gyrus and middle occipital gyrus; and (4) a left ventral prefrontal system covering the superior aspect of inferior frontal gyrus. For phonological processing of written alphabetic words, cortical areas identified here are consistent with the three neural systems proposed previously in the literature: (1) a ventral prefrontal system involving superior portions of left inferior frontal gyrus; (2) a left dorsal temporoparietal system including mid-superior temporal gyri and the ventral aspect of inferior parietal cortex (supramarginal region); and (3) a left ventral occipitotemporal system. Contributions of each of these systems to phonological processing in reading were discussed, and a covariant learning hypothesis is offered to account for the findings that left middle frontal gyrus is responsible for addressed phonology in Chinese whereas left temporoparietal regions mediate assembled phonology in alphabetic languages. Language form, cognitive process, and learning strategy drive the development of functional neuroanatomy.

Brain↗
PubMed1986

[Effects of levels-of-processing on retention of target and nontarget words in a selective attention task].

Effects of levels-of-processing on retention of visually presented target and nontarget letter words were studied in relation to the amount of processing resources expended on the attended task. Attention was directed to targets by the shadowing. Targets and nontargets were distinguished by sensorial or semantic attributes. Processing resources expended were measured by reaction time at an auditory signal during the shadowing. Experiment I, with 20 subjects, showed that recall rate of targets and nontargets was higher and the expended resources were greater, in semantic than in sensorial processing. However, in Experiment II, with 48 subjects, the task difficulty was balanced with respect to shadowing errors and the expended resources were found no more different with different levels-of-processing, while d' measures of targets and nontargets were greater in semantic than in sensorial condition. It was concluded that the effects of levels-of-processing depended not on the resources expended, but on discriminative attributes.

Acoustic Stimulation↗
PubMed1997

The temporal dynamics of reading: a PET study.

The temporal dynamics of evoked brain responses are normally characterized using electrophysiological techniques but the positron emission tomography study presented here revealed a temporal aspect of reading by correlating the duration a word remained in the visual field with evoked haemodynamic response. Three distinct types of effects were observed: in visual processing areas, there were linear increases in activity with duration suggesting that visual processing endures throughout the time the stimulus remains in the visual field. In right hemisphere areas, there were monotonic decreases in activity with increased duration which we relate to decreased attention for longer stimulus durations. In left hemisphere word processing areas there were inverted U-shaped dependencies between activity and word duration indicating that, after 400-600 ms, activity in word processing areas is progressively reduced if the word remains in the visual field. We conclude that these inverted U effects in left hemisphere language areas reflect the temporal dynamics of visual word processing and we highlight the implication of these effects for the design of activation studies involving reading.

Adult↗
PubMedDate not supplied

Semantic relations of the word in aphasics.

The study of the semantic relations of the word in aphasics was performed by an associative experiment applied in two samples, one of 20 aphasic patients and the other of 40 normal subjects. Following application of this associative experiment in normal subjects, a model design was achieved based on the hierarchy of the categories within the semantic field. In this model, the associations were grouped by meaning into semantic categories, while the categories were hierarchized according to the number of words included and to their frequency of association. Comparison of the single model design performed by each aphasic with the normal model design showed a deterioration of the semantic categories, hierarchy, but on a background of a marked reduction of the number of categories within the semantic field of the stimulus. The aphasics lost 2/3 of the associations found in normals but the functionality of the 1/3 left was decreased. This may be the basic reason for the unsuccessful word-finding process in aphasics.

Adult↗
PubMed2004

Semantic short-term memory and its role in sentence processing: a replication.

Previous studies have shown that an aphasic patient (AB) with a semantic short-term memory deficit (STM) had difficulties comprehending and producing sentences with structures that demanded the simultaneous retention of several individual word meanings (Martin & Freedman, 2001a, 2001b; Martin & Romani, 1994; Martin, Shelton, & Yaffee, 1994). The present study provides a replication of these findings with an additional case (ML) who shows a striking dissociation between preserved semantic knowledge and disrupted semantic STM. ML performed poorly on comprehension tasks for sentences that required the retention of single word meanings across several intervening words. In contrast, he did not show an effect of intervening words on processing grammatical relations. ML had difficulty producing adjective-noun phrases, though able to produce the individual nouns and adjectives. These findings support the contention that there is a semantic retention capacity, involved in both comprehension and production, that is separate from semantic knowledge representations.

Aged↗
PubMed1988

Comparison of keyboard, light pen and voice recognition as methods of data input.

There is an increasing requirement for doctors and nurses to interact with computers for clinical and administrative reasons. It is important to assess different methods of computer input to provide the most suitable type of input device for any particular application. A study was undertaken to compare three different input devices--standard 'QWERTY' keyboard, light pen, and voice recognition--for speed, errors and number of corrections during entry of patient admission data. Twenty intensive care nurses took part in the study and were asked to express their assessment of speed, accuracy, ease of use and preference. The average speed of data entry by keyboard (37.70 s) was significantly faster than light pen (58.09 s; p less than 0.001); while light pen entry was significantly faster than voice recognition (111.65 s; p less than 0.001). There was no difference between the average number of errors for keyboard (0.10) and light pen (0), but significantly more errors occurred with voice recognition (1.05) than light pen (p less than 0.001). Significantly more corrections were required with the light pen (0.50) compared with the keyboard (0; p less than 0.001), and between voice recognition (11.95) and light pen (p less than 0.001). Keyboard input was considered by the intensive care unit staff as the quickest, most accurate, easiest and most preferred method of entering data into a computer.

Electronic Data Processing↗