Lexical access in mild cognitive impairment

2015 ◽  
Vol 10 (2) ◽  
pp. 271-285 ◽  
Author(s):  
Vanessa Taler ◽  
Shanna Kousaie ◽  
Christine Sheppard
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Lexical Decision ◽  
Lexical Processing ◽  
Contextual Information ◽  
Low Frequency ◽  
Unrelated Word ◽  
Decision Task ◽  
Frequency Effects ◽  
Lexical Activation

We examined the use of sentence context in lexical processing in aging and mild cognitive impairment (MCI). Younger and older adults and participants with MCI completed a lexical decision task in which target words were primed by sentences biasing a related or unrelated word (e.g., prime: “The baby put the spoon in his ______”, biased word: “mouth”, related target: “KISS”, unrelated target: “LEASH”). Biased items were of high or low frequency. All participants responded more quickly when the biased word was of high than low frequency, regardless of whether the target and biased word were related. Frequency effects were stronger in related than unrelated stimuli, and MCI participants – but not controls – responded more slowly when the target was related to a low-frequency word than when it was unrelated. We hypothesize that this effect results from slowed lexical activation in MCI: low frequency expected words are not completely activated when the target word is presented, leading to increased competition between the expected and target items, and resultant slowing in lexical decision on the target. These results indicate that MCI participants can use contextual information to make predictions about upcoming lexical items, and that information about lexical associations remains available in MCI.

scholarly journals Lateralızatıon of Non-Word Processıng in Monolınguals

2020 ◽  
Vol 15 ◽  
pp. 185-190
Author(s):  
Filiz Mergen ◽  
Gulmira Kuruoglu
Keyword(s):  
Lexical Decision ◽  
Lexical Decision Task ◽  
Left Hemisphere ◽  
Word Processing ◽  
Lexical Processing ◽  
Response Times ◽  
Hemispheric Dominance ◽  
Decision Task ◽  
Visual Hemifield ◽  
Overwhelming Evidence

A great bulk of research in the psycholinguistic literature has been dedicated to hemispheric organization of words. An overwhelming evidence suggests that the left hemisphere is primarily responsible for lexical processing. However, non-words, which look similar to real words but lack meaningful associations, is underrepresented in the laterality literature. This study investigated the lateralization of Turkish non-words. Fifty-three Turkish monolinguals performed a lexical decision task in a visual hemifield paradigm. An analysis of their response times revealed left-hemispheric dominance for non-words, adding further support to the literature. The accuracy of their answers, however, were comparable regardless of the field of presentation. The results were discussed in light of the psycholinguistic word processing views.

scholarly journals Aggregation of Vascular Risk Factors Modulates the Amplitude of Low-Frequency Fluctuation in Mild Cognitive Impairment Patients

2020 ◽  
Vol 12 ◽  
Author(s):  
Liying Zhuang ◽  
Huafu Ni ◽  
Junyang Wang ◽  
Xiaoyan Liu ◽  
Yajie Lin ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Brain Activity ◽  
Low Frequency ◽  
Vascular Risk Factors ◽  
Vascular Risk ◽  
Cvd Risk ◽  
Spontaneous Brain Activity ◽  
Main Effect

Background: Several vascular risk factors, including hypertension, diabetes, body mass index, and smoking status are found to be associated with cognitive decline and the risk of Alzheimer's disease (AD). We aimed to investigate whether an aggregation of vascular risk factors modulates the amplitude of low-frequency fluctuation (ALFF) in patients with mild cognitive impairment (MCI).Methods: Forty-three MCI patients and twenty-nine healthy controls (HCs) underwent resting-state functional MRI scans, and spontaneous brain activity was measured by the ALFF technique. The vascular risk profile was represented with the Framingham Heart Study general cardiovascular disease (FHS-CVD) risk score, and each group was further divided into high and low risk subgroups. Two-way ANOVA was performed to explore the main effects of diagnosis and vascular risk and their interaction on ALFF.Results: The main effect of diagnosis on ALFF was found in left middle temporal gyrus (LMTG) and left superior parietal gyrus (LSPG), and the main effect of risk on ALFF was detected in left fusiform gyrus (LFFG), left precuneus (LPCUN), and left cerebellum posterior lobe (LCPL). Patients with MCI exhibited increased ALFF in the LMTG and LSPG than HCs, and participants with high vascular risk showed increased ALFF in the LFFG and LCPL, while decreased ALFF in the LPCUN. An interaction between diagnosis (MCI vs. HC) and FHS-CVD risk (high vs. low) regarding ALFF was observed in the left hippocampus (LHIP). HCs with high vascular risk showed significantly increased ALFF in the LHIP than those with low vascular risk, while MCI patients with high vascular risk showed decreased ALFF in the LHIP than HCs with high vascular risk. Interestingly, the mean ALFF of LHIP positively correlated with word recall test in HCs with high vascular risk (rho = 0.630, P = 0.016), while negatively correlated with the same test in MCI patients with high vascular risk (rho = −0.607, P = 0.001).Conclusions: This study provides preliminary evidence highlighting that the aggregation of vascular risk factors modulates the spontaneous brain activity in MCI patients, and this may serve as a potential imaging mechanism underlying vascular contribution to AD.

Morpheme frequency effects in Dutch complex word reading: A developmental perspective

2011 ◽  
Vol 32 (3) ◽  
pp. 483-498 ◽  
Author(s):  
LUDO VERHOEVEN ◽  
ROB SCHREUDER
Keyword(s):  
Lexical Decision ◽  
Lexical Decision Task ◽  
Word Reading ◽  
Word Identification ◽  
Low Frequency ◽  
Decision Task ◽  
Word Form ◽  
Word Forms ◽  
Grade 3 ◽  
Complex Words

ABSTRACTThis study examined to what extent advanced and beginning readers, including dyslexic readers of Dutch, make use of morphological access units in the reading of polymorphemic words. Therefore, experiments were carried out in which the role of singular root form frequency in reading plural word forms was investigated in a lexical decision task with both adults and children. Twenty-three adult readers, 37 8-year-old children from Grade 3, 43 11-year-old children from Grade 6, and 33 11-year-old dyslexic readers were presented with a lexical decision task in which we contrasted plural word forms with a high versus low frequency of the singular root form. For the adults, it was found that the accuracy and speed of lexical decision is determined by the surface frequency of the plural word form. The frequency of the constituent root form played a role as well, but in the low-frequency plural words only. Furthermore, a strong developmental effect regarding the accuracy and speed of reading plural word forms was found. An effect of plural word form frequency on word identification was evidenced in all groups. The singular root form frequency also had an impact of the reading of the plural word forms. In the normal reading and dyslexic children, plurals with a high-frequency singular root form were read more accurately and faster than plurals with a low singular root frequency. It can be concluded that constituent morphemes have an impact on the reading of polymorphemic words. The results can be explained in the light of a word experience model leaving room for morphological constituency to play a role in the lexical access of complex words as a function of reading skill and experience and word and morpheme frequency.

Priming and the Effects of Sentence and Lexical Contexts on Naming Time: Evidence for Autonomous Lexical Processing

1981 ◽  
Vol 33 (4) ◽  
pp. 465-495 ◽  
Author(s):  
K. I. Forster
Keyword(s):  
Lexical Decision ◽  
Language Processing ◽  
Lexical Processing ◽  
Naming Task ◽  
Decision Time ◽  
Semantic Integration ◽  
Access Time ◽  
Decision Task ◽  
Naming Time ◽  
Inhibitory Effects

Models of language processing which stress the autonomy of processing at each level predict that the semantic properties of an incomplete sentence context should have no influence on lexical processing, either facilitatory or inhibitory. An experiment similar to those reported by Fischler and Bloom (1979) and Stanovich and West (1979, 1981) was conducted using naming time as an index of lexical access time. No facilitatory effects of context were observed for either highly predictable or semantically appropriate (but unpredictable) completions, whereas strong inhibitory effects were obtained for inappropriate completions. When lexical decision time was the dependent measure, the same results were obtained, except that predictable completions now produced strong facilitation. In a further experiment the inhibitory effects of context on lexical decision times for inappropriate targets were maintained, even though unfocussed contexts were used, in which no clear expectancy for a particular completion was involved. These results were interpreted in terms of a two-factor theory which attributes the facilitation observed with the lexical decision task to postaccess decision processes which are not involved in the naming task. The inhibitory effects were attributed to interference resulting from semantic integration. In contrast to the results for sentence contexts, lexical contexts of the doctor-nurse variety produced clear facilitation effects on naming time (but no inhibitory effects). It was also shown that relatively minor variations in the type of neutral context could completely alter the relative importance of facilitation and inhibition.

scholarly journals A mare in a pub? Nonnative facilitation in phonological priming

2018 ◽  
Vol 36 (1) ◽  
pp. 123-140 ◽  
Author(s):  
Kira Gor ◽  
Svetlana V Cook
Keyword(s):  
Lexical Processing ◽  
Native Speakers ◽  
Low Frequency ◽  
Nonnative Speakers ◽  
Unrelated Word ◽  
Phonological Priming ◽  
Lexical Competition ◽  
Sublexical Processing ◽  
English Speaking ◽  
Prime Target

A phonological priming experiment reports inhibition for Russian prime-target pairs with onset overlap in native speakers. When preceded by the phonological prime /kabɨla/, the target /kabak/ ( кобыла – КАБАК, mare – PUB) takes longer to respond than the same target preceded by a phonologically unrelated word. English-speaking late learners of Russian also show inhibition, but only for high-frequency prime-target pairs. Conversely, they show facilitation for low-frequency pairs. In semantic priming (e.g. carnation – DAISY), facilitation is observed for the same two lexical frequency ranges both in native speakers and learners of Russian, suggesting that the primes and targets in the low-frequency range are familiar to the nonnative participants. We interpret nonnative phonological facilitation for low-frequency words as evidence for sublexical processing of less familiar words that is accompanied by reduced lexical competition in nonnative lexical access. We posit that low lexical competition is due to unfaithful, or fuzzy phonolexical representations: nonnative speakers are unsure about the exact phonological form of low-frequency words. Such unfaithful representations are not strongly engaged in lexical competition and selection. High reliance on sublexical rather than lexical processing may be a general property of nonnative word recognition in case when the words are less familiar and have a low level of entrenchment.

Lexical dynamics for low-frequency complex words

2007 ◽  
Vol 2 (3) ◽  
pp. 419-463 ◽  
Author(s):  
R. H. Baayen ◽  
Lee H. Wurm ◽  
Joanna Aycock
Keyword(s):  
Word Recognition ◽  
Theoretical Analysis ◽  
Lexical Decision ◽  
Target Word ◽  
Low Frequency ◽  
Mixed Effects ◽  
Frequency Range ◽  
Frequency Effects ◽  
Complex Words ◽  
Root Frequency

In this study we examine the word recognition process for low-frequency morphologically complex words. One goal of the study was to replicate and expand upon findings suggesting facilitative effects of morphological relatives of a target word. A second goal was to demonstrate the need for a reinterpretation of root and surface frequency effects, which traditionally have been taken as indicators of parsing-based and memory-driven processing, respectively. In a first study, we used the same stimuli across auditory and visual lexical decision and naming. Mixed-effects statistical modeling revealed that surface frequency was a robust predictor of RTs even in the very low end of the distribution, but root frequency was not. Also, the nature of the similarity between a target and its lexical competitors is crucial. Measures gauging the influence of morphological relatives of the target were facilitative, while measures gauging the influence of words related only in form were inhibitory. A second study analyzing data from the English Lexicon Project, for a large sample of words from across the full frequency range, supports these conclusions. An information-theoretical analysis of root and surface frequency explains why surface frequency must be the most important predictor, with only a marginal role for root frequency.

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