Accessing the mental lexicon

Lexical Access, Cognitive Psychology of

BackgroundLexical access refers to the generation or retrieval of conceptual representation. Representation of concepts or semantic knowledge involves the organization of concepts in an associative manner building up the mental lexicon. Several studies have pointed out an early presence of lexical access failure in Alzheimer’s Disease(AD). While lexical access deficit is rampant among patients with AD, the underlying processes involved in retrieval failure remain debatable. Some findings suggest that the difficulty in lexical access can be due to a deterioration in the conceptual representation. Therefore, to understand the nature of the difficulty underlying lexical access failure among people with AD, the current study aims to understand the involvement of semantic knowledge in lexical access.MethodIn this study, three groups of participants will be recruited, Healthy Controls (HC), Mild Cognitive Impairment (MCI) and Dementia with AD. According to apriori sample size calculation, a total sample size of 54 would be required for the present study, with 18 participants per group. In the current study, the semantic priming task is used to understand the ongoing debate about the involvement of semantic knowledge in Lexical access. The experiment consists of 4 tasks to probe their semantic knowledge and visual perception. Each trial consists of a prime‐ image or word, presented for some duration followed by a related or unrelated target. The participant needs to report whether the target was related to the prime or not.ResultThe lexical retrieval is expected to be differentiated along the different phases of the disease as a function of semantic priming. It is expected that the lexical retrieval in the HC group would be least impacted across the three conditions and AD with Dementia to be the most impacted. The performance on each condition could be differentiated across each disease severity group, along with a difference in the prime type, that is, primes related to the target would show better performance than unrelated primes across all the conditions in each of the groups.ConclusionThe findings from this study would contribute towards understanding processes underlying lexical access failure among people with Alzheimer’s Disease.

During the fourth age (80+ years), cognitive difficulties increase. Although language seems to resist the advancement of age, an older person without pathological developments in cognition may exhibit deficits in lexical access. This study examines the restrictions on lexical access in people aged 80 and older in word recognition and retrieval modalities through four lexical tasks. The effect of aging on response time and accuracy was measured using recognition (lexical decision/naming/priming) and retrieval (picture naming) tasks. A fourth age group (>80) and two third age groups (60-69/70-79) were compared according to lexical access modality and type of task employed through linear regression models. People aged 80 and older exhibit a strong lexical access constraint, as they are slower and less accurate in recognizing and retrieving words than both third age groups. These restrictions are more profound for the word retrieval modality, especially in the picture naming task. Impaired fluid intelligence and internode transmission deficits during advanced aging could further reduce the ability to recognize and/or retrieve words, having an impact on access speed and accuracy. Furthermore, the idea that crystallized intelligence could strengthen the accuracy of lexical access during aging is supported, specifically in word recognition modality.

This is a doctoral thesis in computational psycholinguistics, an interdisciplinary research field combining expertise and experiences in linguistics, psychology, and computer science. The thesis takes as a subject the simulation of human word recognition, that is, it aims at modeling on the computer the cognitive process of how we activate and access words, their forms, and their constituting components, in our mental lexicon. It concerns spoken (rather than written) word units and consequently deals with the simulation of auditory (in contrast to visual) word recognition. Specifically, this thesis puts forward two new models that we have developed and built ourselves: One is named FN5 and simulates spoken word recognition in monolinguals; the other, called BIMOLA, models spoken word recognition in bilinguals. The monolingual model FN5 is on French and therefore contains a lexicon of 17,668 French words (nouns, determiners, and prenominal adjectives), some of which having variants and giving rise to a total of 20,523 pronunciations. FN5 processes single (i.e. isolated) words as well as sequences of two connected words (determiner + noun, or prenominal adjective + noun). It implements a new approach to recognizing sequences of words, by means of optimizing the words’ alignment positions and pronunciation variants. In addition, it provides for several phonological phenomena that can take place within a word or at boundaries between words (deletion of schwa, linking with and without liaison, word contractions including elision). To account for dialectal differences, it may be run in either of two versions, standard French or Swiss French. The bilingual model BIMOLA deals with two languages all at once, English and French; it includes an English-French bilingual lexicon of 8,696 words (all verbs, 4,348 for each language); and it operates in various language modes (i.e. global configurations of the bilingual’s two languages). BIMOLA is able to identify words from either language (always single words, to keep things easy), including guest words, that is, code-switches and borrowings from one into the other language. The two models share a phonetic feature matrix that represents similarities and differences of phonemes both within and between the languages and dialects. As revealed in the evaluations, both our models have a great overall recognition performance and are able to simulate a large number of specific psycholinguistic effects.

Chapter 21 Memory-addressing Mechanisms and Lexical Access

The present paper explores the lexical profiles of monolingual and bilingual learners acquiring English as a second and third language, respectively. Those profiles allow to get insights into learners’ lexical access and lexical organization in the new language. To shed more light in this issue, a lexical fluency task was used to gather data. Results showed lack of significant differences in all the measures taken, but some very interesting differences appear when graph theory metrics are applied. Thus, educational bilinguals show higher levels of lexical organization and stronger connections among the nodes. This can be indicative of a mental lexicon which is better organized, more compact, and more stable. Additionally, educational bilinguals’ networks display highest clustering coefficient and shortest path length. In semantic terms, this means that educational bilinguals can navigate their lexicon more efficiently and in a way that better resembles native lexical search. These findings open up new avenues for insightful studies concerning lexicon organization in different types of learners, with bilingualism being a relevant modulating factor.

ABSTRACTRecent research has suggested an important role for spatial attention in reading, however the nature of this influence is unclear. Further, it has been shown that intention to engage in linguistic processing can enhance lexical processing. Therefore, we developed a novel paradigm to examine the impact of spatial attention on primed and unprimed lexical processing. In a lexical decision task, targets were preceded by a cue to lexical access and spatial location simultaneously. Results indicated that on spatially valid trials, the lexical cuing effect was large and word processing was enhanced, suggesting that spatial attention influences lexical access. On spatially invalid trials, lexical cuing effects were significantly decreased, resulting in a spatial cuing by lexical cuing interaction. Results from this experiment provide evidence that spatial attention interacts with lexical access during word processing. This novel paradigm provides a new avenue for exploring the relations between spatial attention and reading processes.

Oral fluency is widely included in second language assessments, but its relationship to language proficiency is not straightforward. In the current study, data gathered in an experimental setting were examined with an exploratory fluency analysis. The aim was to examine the relationship between fluency of lexical access and proficiency in foreign language (L2). Fluency of the lexical access was studied by analysing inaccuracies in one word recognition and one word retrieval task. To see if proficiency had an effect on the number and the type of inaccuracies, lexical access tasks were carried out for 563 Finnish school children from grades 4, 8, and 11 in their L2 (English). Proficiency in L2 was expected to develop during school education. The inaccuracies were proposed to stem from processing limitations in language use, i.e., inefficiency of lexical access, or from control of attention. The hypothesis was that if lexical access is not automatized, there are less resources for attention-control in recognising and retrieving words. Therefore, the inaccuracies in L2 relating to inefficiency were hypothesised to decrease with proficiency, whereas the ones relating to control of attention were proposed to be more stable or to increase. Furthermore, the fluency of L1 lexical access was used as a control measure. The results offered some confirmation to these hypotheses. For example, some evidence for more available resources in correcting and monitoring speech was found for the older students. The overall results highlight caution in assessing L2 fluency, as not all types of inaccuracies were connected with lower proficiency.

Lexical access in the production of noun phrases

Learning and speaking foreign languages are regarded today as the norm. Simultaneously, empirical findings in the area of multilingualism have recently demonstrated that the mental lexicon of a language learner consists of intertwined systems where languages interact with each other, rather than remain separate entities. However, studies that explore how different lexicons are integrated and influence each other in the case of multilinguals are relatively scarce. This thesis seeks to contribute to this gap in research reporting two empirical studies drawing on a vocabulary testing perspective. The studies investigate the impact of prior lexical knowledge on additional language learning of Hungarian native speakers, who speak Romanian as an L2 and English as an L3. From a theoretical standpoint, the studies contest the traditional assumption that foreign language vocabulary acquisition can be explained solely by measures of frequency of word occurrence. Instead is contended that cross-linguistic similarities, namely cognates, provide a special bridge between languages and also need to be taken into account. At a more substantive level, it aims to explore (1) the relationship between learners’ Romanian and English written lexical knowledge; (2) the facilitatory effect of cognates; and (3) the implications of this for vocabulary assessments. To address these aims, Romanian versions of Nation’s Vocabulary Levels Test (VLT) and Vocabulary Size Test (VST) have been developed, assessed for validity, and applied. The findings indicate that there is a strong connection between multilinguals’ Romanian L2 and English L3 lexica. Learners’ lexical proficiency can be described as a function of frequency but is also influenced by cognateness. Therefore, word frequency and cognateness in conjunction can potentially increase test accuracy and validity, and enable a more in-depth understanding of vocabulary size and lexical accessibility. These conclusions are drawn from a vocabulary testing perspective, but further pedagogical implications, future directions for research and limitations are also offered.

Associations and manipulations in the mental lexicon: A model of word-stem completion

This study explored the role of attentional and perceptual factors in lexical access by examining the effects of acoustic distortion on semantic priming of spoken words by a sentence context. The acoustic manipulations included low-pass filtering, which was intended to interfere with the sensory encoding of the acoustic signal by reducing intelligibility, and time compression, which was intended to disrupt central language processing by reducing processing time. These distortions were applied to the sentence context to explore how the contribution of contextual information to lexical access is affected by acoustic degradation. Low-pass filtering significantly reduced semantic facilitation. In contrast, temporal compression significantly reduced semantic inhibition without affecting facilitation. These qualitative differences between two forms of acoustic distortion are discussed in terms of the activation, selection, and integration of lexical-semantic information in models of lexical access. Filtering may have its primary effect on a relatively early, automatic process (reflected in facilitation effects), while compression has its primary effect on a later, more demanding process (reflected in inhibition effects). Practical and theoretical implications for higher-level language processing in hearing-impaired and elderly populations are discussed.

Introduction: Working memory is assumed to play a major part in hearing and communication in everyday listening situations. Our working memory stores information, but in suboptimal listening conditions, interfering stimuli can lead to information only being partially stored, or even missed. Research suggests that a high working memory capacity (WMC) might not just be a result of a large store, but in addition good inhibitory control can facilitate working memory, and therefore aid in situations where focus on a target stimulus while ignoring distractors is needed.Objective: The aim of the present study was to investigate how individual WMC, cognitive inhibition, and lexical decision relate to listening to speech under adverse conditions in two separate groups: 46 young normally hearing (NH) and 40 elderly hearing-impaired (HI) individuals.Results: It showed that lexical access was of little importance for young NH individuals in a speech-in-noise test, but that high lexical decision-making was associated with lower signal-to-noise ratios for the elderly HI individuals. The results also showed that WMC was of importance for word recognition in a speech-in-noise test for elderly participants, when the 80% word recognition criterion was targeted, but not for the young NH individuals. Finally, results suggest that cognitive inhibition, as measured with the Hayling task, was important for young NH individuals when listening conditions are suboptimal.Conclusion: In conclusion, hearing loss is a strong contributing factor to declines in the ability to recognize speech in noise, and in order to assess speech-recognition-in-noise performance, individual differences in WMC and cognitive inhibition should be taken into consideration. Future research should include various age groups, with and without hearing loss, as well as measures of WMC, cognitive inhibition, and lexical access when assessing the ability to listen to speech under adverse conditions.

Lexical stress patterns appear to be important in word recognition processes in normal individuals. The present investigation employed a lexical decision task to assess whether left (LHD) and right hemisphere damaged (RHD) patients are similarly sensitive to stress patterns in lexical access. The results confirmed that individuals without brain damage are influenced by stress patterns, as indicated by increased lexical decision latencies to incorrectly stressed word and nonword stimuli. The data for the LHD patients revealed an effect of stress for real word targets only, whereas the reaction time data for the RHD patients as a group showed no significant influence of stress pattern. However, there was a great deal of individual variability in performance. The latency and error rate findings suggest that LHD patients and non-brain-damaged individuals are both sensitive to lexical stress in word recognition, but the LHD patients are more likely to treat incorrectly stressed items as nonwords. The results are discussed in relation to theories of the hemispheric lateralization of prosodic processing and the role of lexical stress in word recognition.

The purpose of the study was to examine the perceptual effects of altering lexical stress during word recognition. A detection task was utilized to measure subjects’ speed of response to target phonemes preceded by two-syllable homograph and nonhomograph words. These experimental words were pronounced with correct/incorrect lexical stress. When a nonhomograph was misstressed, a nonsense word was the result. When a homograph was misstressed, another English word resulted. Examination of subjects’ speeds of response to target phonemes preceded by correctly/incorrectly stressed nonhomograph words indicated slower speed of response when the stimulus word was stressed incorrectly; word recognition appeared to be affected when a subject heard a misstressed nonhomograph (a nonsense word). However, subjects’ speed of response to target phonemes following correctly/incorrectly stressed homographs were similar. Mispronounced homographs did not appear to impede word recognition. It was possible that when subjects heard a misstressed homograph (another English word), they relied more upon the prosodie contour for word recognition.