Psycholinguistics: Analysis of Knowledge Domains on Children’s Language Acquisition, Production, Comprehension, and Dissolution

This paper utilised bibliometric and scientometric indicators to assess the current state of research in psycholinguistics. A total of 32,586 documents in psycholinguistics were included from Scopus, WOS, and Lens between 1946 and 2022. The collected data were analysed using CiteSpace 5.8.R3 and VOSviewer 1.6.18. The results included tabulation, visualisation, and mapping for the past, present, and future directions of the field of psycholinguistics. We identified key authors, works, journals, and concepts in the existing evidence concerning (children’s) language acquisition, production, comprehension, and dissolution. The study contributes to the systematic study of existing scholarship in the field of psycholinguistics by documenting the progress of the field and informing relevant researchers about the current state of the field of psycholinguistics. Having grouped the 32,586 documents in psycholinguistics, 12 clusters were identified. These include (1) examining individual difference in affective norm and familiarity account; (2) examining refractory effect in the role of Broca’s area in sentence processing; (3) using eye movement to study bilingual language control and familiarity account; (4) exploring familiarity account through relative clauses; (5) the study of formulaic language and language persistence; (6) examining affective norm and sub-lexical effect in Spanish words; (7) examining lexical persistence in multiplex lexical networks; (8) the study of persistence through cortical dynamics; (9) the study of context effect in language learning and language processing; (10) the study of neurophysiological correlates in semantic context integration; (11) examining persistence as an acquisition norm through naming latencies; and (12) following a cross-linguistic perspective to study aphasic speakers.


Introduction
There is no doubt that children play a crucial role in the continuity of the human species. From the moment they are born, they go through several developmental stages. Language is one of these developmental stages in which they progress from acquisition to production to comprehension, and then, during any of these stages, they may experience language dissolution. Beginning with cooing, babbling, early words, and early grammar, the children will progress step by step to become able to communicate and use language appropriately. Through conceptualization, formulation, articulation, and self-monitoring, children can correctly produce language. Furthermore, they will be able to comprehend sounds, words, sentences, texts, and language beyond the words or intended meanings of the texts. In the following section, we will introduce the history of psycholinguistics; discuss its scope, including its definition(s) and scientific contributions; and conclude with the main purpose of this study.

Formative Period
In 1951, linguistics and psychology formally met for the first time at a seminar of Social Science Research at Cornell University. As a result of this meeting, a committee on linguistics and psychology was formed. The key issues investigated during this time were: how people comprehend and produce language, how and under what circumstances they lose language, how a particular language affects cognition, and the connection between the first and foreign language learning. During in the formative period, the dominant paradigm in linguistics was structuralism and the trend in psychology was behaviourism. Hence, both disciplines adopted a behaviourism approach [7,9,12].

Linguistic Period
Psycholinguistics was controlled during this period by generative grammar for the sake of studying language comprehension. There was a belief that understanding speakers' competence gives a picture about the nature of speakers' actual performance. According to the transformational generative grammar, the sentence has a significant role in explaining the grammar's data and dimensions. Thus, they study the comprehension and use of sentences [7,9,12].
The American psychologist George A. Miller was one of the founders of cognitive psychology and cognitive neuroscience. His research contributed to psycholinguistics and the study of human communication and was considered a bridge between linguistic theory and psychological experimentation. In 1951, he wrote his first book entitled Language and Communication, which was regarded as a fundamental work in psycholinguistics. This period gradually encouraged a more interdisciplinary in psycholinguistics than in the formative period [13].

Cognitive Period
The dependence of language upon human cognition is the main premise behind the cognitive approach. Language is considered "one of several fundamental cognitive process outcomes" [9] (p. 144). Psycholinguistics was a branch of cognitive psychology and was entirely independent of linguistics. Thus, psycholinguistic research within this period examined language from the perspective of cognitive psychology. The best early examples of this approach are Bever [14] and Slobin [15]. Bever's goal was improving the uses of human language through the application of linguistics, psycholinguistics, and cognitive science [14]. Slobin's work also highlighted the significance of cross-linguistic comparison on the investigations of language acquisition and psycholinguistics in general [15]. During the 1980s, psycholinguistics involved studying first and other language learning, children's language acquisition, and linguistic disabilities. Ayudhya mentioned three key questions of psycholinguistics research during this time [9]: (a) The study of the link between psychology and linguistics in mental representations and language processing; (b) The study of the language-processing processes that mental representation of speakers transformed from a process into another; (c) The study of overall language processing in which each level of language processing interacts with the other levels.

Psycholinguistics Theory Period
In the 1980s, there was a shift in psycholinguistics progression. None of psychology or linguistics dominated psycholinguistics. Moreover, because of the influence of cognitive science in the previous period, it was demonstrated that psycholinguistics can be studied as the scientific comprehension of the way in which the human mind is involved in how language works. Therefore, psychological reality can be investigated scientifically in psycholinguistic theory. In this period, cognitive psychology and linguistics merged, and psycholinguistic research contributed to a realistic science of the human mind [9].
Psycholinguistics has developed into an interdisciplinary field. That is, other disciplines such as biology, neuroscience, psychology, cognitive science, computer sciences, and language teaching and learning are applied to investigate language processing [16].

The Scope of Psycholinguistics
The section above leads us to the inevitable question: what is psycholinguistics? There are several definitions of this science, which are similar in certain aspects and different in others. These differences could arise from researchers' different views and backgrounds and from their arrangement of its topics [4].
Psycholinguistics is an interdisciplinary field of study that can be defined as "the study of the mental representations and processes involved in language use, including the production, comprehension and storage of spoken and written language" [17] (p. 4). Warren proposed that psycholinguistics consists of language processes, production, and comprehension. Language processes are either central or peripheral. Language production includes intention, planning, lexicalization, and articulation. Language comprehension consists of perception, word recognition, parsing, and interpretation. He added that these processes undergo different linguistic levels: phonological, phonetic, morphological, syntactic, sematic, and then discourse analysis [17] (p. 5).
More interestingly, the American Psychological Association (APA) dictionary of psychology considers psycholinguistics as a branch of psychology and defines it as [18]: A branch of psychology that employs formal linguistic models to investigate language use and the cognitive processes that accompany it. Developmental psycholinguistics is the formal term for the branch that investigates language acquisition in children. In particular, various models of generative grammar have been used to explain and predict language acquisition in children and the production and comprehension of speech by adults. To this extent, psycholinguistics is a specific discipline, distinguishable from the more general area of psychology of language, which encompasses many other fields and approaches.
Other researchers such as Issa and Awadh considered psycholinguistics as interdisciplinary branch of linguistics that concerns "the cerebral foundations of language usage" [19] (p. 20), which is obviously linked to areas of linguistic study (i.e., phonetics, phonology, morphology, syntax, semantics, and discourse analysis) [17], while others such as Fernandez and Cairns took a broader view and pertained psycholinguistics to psychology and linguistics as a sub-discipline of them both, yet emphasizing that it is also associated with developmental psychology, cognitive psychology, speech science, and neurolinguistics [20].
Psycholinguistics aims at understanding how individuals acquire language, how they use language to speak and understand each other, and how language is represented and processed in the brain [20]. Hence, we can say the core goal of this interdisciplinary field of study is developing a coherent theory about how humans comprehend and produce language [21,22].
Since the scope of this discipline is to investigate how language is used and learned [23], it is, as stated in the APA Encyclopaedia of Psychology [24], related to: the traditional academic disciplines of linguistics, psychology, education, the cross-disciplinary areas of speech science, cognitive science, artificial intelligence, neurolinguistics, language learning, teaching, and rehabilitation.
To sum up, psycholinguists study the psychological processes involved in the language usage, including language understanding, language production, and first and second language acquisition [25].

Scientific Contributions for Psycholinguistics
In this section, we attempt to shed light on scientific contributions made to psycholinguistics, i.e., journals and associations dedicated to the field. Table 1 shows a breakdown of Children 2022, 9, 1471 6 of 39 the data. We should point out that we only included journals, associations, and research centres with the words "psycholinguistics" or "psycholinguistic" in their titles.

Purpose of the Present Study
Psychology has been credited with advancing the study of human thought and behaviour, including language, in past reviews of psycholinguistics [26]. In the late 19th century and early 20th century, behaviourism dominated the explanation and research evidence concerning the psycholinguistic processes associated with human language. In the second half of the 20th century, however, this changed with the rise of Chomsky's theory of language [27]. With the advancement of technology during the early 21st century, the study of psycholinguistics shifted to a computational model of language and speech processing using a connectionist approach [28]. There was also an increase in cross-linguistic studies aimed at identifying universal aspects of children's language development, usage, and breakdown across languages [29].
As the study of psycholinguistics progresses, many researchers have criticized the focus on monologues in empirical evidence rather than the sociocultural implications of dialogue-based evidence [30]. There has been an expansion of psycholinguistics to examine more specific aspects of human language, such as the production of language [31] and integrating the study of language with the cognitive sciences [32]. Recent reviews of psycholinguistics have focused on the use of offline measures of language comprehension [33], psycholinguistics and teaching and learning settings to enhance education [34], and the syntactic and cognitive aspects of language acquisition and learning [35]. Recent bibliometric analyses examined data from 1900 to 2021 concerning child language, which is the subject of psycholinguistic research. However, this review limited its data collection to articles and only used the WOS [36].
In this study, we examine the development of the field of psycholinguistics and the evidence regarding how (children) acquire, learn, process, comprehend, and produce language. The difference between this study and previous ones is that it is more comprehensive in that it includes data from 1946 to 2022. As part of the triangulation process, three databases were used (Scopus, WOS, and Lens) to ensure the data are not biased towards particular journals within the field. In addition, it combines bibliometric and scientometric indicators to analyse state-of-the-art psycholinguistic scholarship. As a result, this study seeks to apply the science mapping approach [37] "to detect and visualize emerging trends and radical changes" [38] (p. 374) and patterns in literature [39] pertaining to psycholinguistics.
It should be noted that our research in this study is restricted to articles with the term "psycholinguistic*" in their title, abstract, author keywords, and topic. Examining the use of "psycholinguistics" or "psycholinguistic" concepts is the raison d'être of this exclusion. This means that, while we are aware that numerous other topics and themes (e.g., first language acquisition, second language acquisition, language learning, child language, etc.) are within the scope of psycholinguistic research, we avoided making our resarch lengthy and instead focused on the use and development of the two concepts listed above. The following questions therefore guided our research: (1) What is the size of psycholinguistics' knowledge production over the past seventy-six years as measured by year, region, institutions, journal, publisher, research area, author, and cited documents? (2) Who are the most influential and central authors in the field of psycholinguistics? (3) What are the most sought-after terms and keywords in psycholinguistics? (4) Which patterns are the most investigated and studied in psycholinguistics?

Research Methods
Scientometrics is the methodology for examining artifacts or objects; one examines not the process of science and scholarship but the outcome of these activities [40] (p. 491). Scientometrics studies "the quantitative aspects of the production, dissemination and use of scientific information with the aim of achieving a better understanding of the mechanisms of scientific research as a social activity" [41] (p. 6). Research of this type may aim to improve the quality of publications, but its purpose is not entirely clear. According to previous research, "the task of determining quality papers is especially difficult in BIS (bibliometrics, informetrics and scientometrics) due to the very heterogeneous origin of the researchers" [42] (p. 390). Nevertheless, these studies aim to "reveal characteristics of scientometric phenomena and processes in scientific research for more efficient management of science" [43] (p. 1).
A scientometric indicator guides studies of this nature. A number of factors are taken into account (e.g., publications, citations and references, potential, etc.) as well as type indicators [43]. The most common method used in such studies is "mapping knowledge domains", which refers to creating "an image that shows the development process and the structural relationship of scientific knowledge" and using maps that are "useful tools for tracking the frontiers of science and technology, facilitating knowledge management, and assisting scientific and technological decision-making" [44] (p. 6201). It is currently becoming more common for research of this type to include all fields of study without limiting itself to medical, health, and pure sciences [45]. This study examines psycholinguistics as a sub-field of linguistics that integrates psychology and linguistics.

Measures
It is widely acknowledged that studies in bibliometrics and scientometrics are valuable tools for guiding the assessment of knowledge produced in the field or concept under consideration (e.g., psycholinguistics). Most knowledge databases (e.g., Scopus, WOS, and Lens) contain bibliometric indicators [46][47][48][49]. Scientometric indicators are provided by a scientometric program. This study used CiteSpace 5.8.R3 [50] and VOSviewer 1.6.18 [51]. Table 2 lists the bibliometric and scientometric indicators used in this study. Betweenness centrality A path between nodes and is achieved when located between two nodes [53]. √ X Burst detection Determines the frequency of a certain event in certain period (e.g., the frequent citation of a certain reference during a period of time) [54].

Co-citation
When two references are cited by a third reference [55]. CiteSpace provides document co-citation network for references and author co-citation network for authors. In VOSviewer, co-citation defined as "the relatedness of items is determined based on the number of times they are cited together" [51] (p. 5). Units of analysis include cited authors, references, or sources.

√ √
Silhouette Used in cluster analysis to measure consistency of each cluster with its related nodes [50].
To measure strength of a node in terms of betweenness centrality citation burst [50]. √ X Clusters "We can probably eyeball the visualized network and identify some prominent groupings" [50] (p. 23).

√ √
Citation "The relatedness of items is determined based on the number of times they cite each other" [51] (p. 5). Units of analysis include documents, sources, authors, organizations, or countries.

√ √
Keywords CiteSpace provides co-occurring author keywords and keywords plus.
In VOSviewer, co-occurrence analysis is defined as "the relatedness of items is determined based on the number of documents in which they occur together" [51] (p. 5). Units of analysis include author keywords, all keywords, or keywords plus.

Data-Collection and Sample
The data were retrieved using Scopus, WOS, and Lens. These databases were included for a variety of reasons. WOS and Scopus initially cover only publications that match their criteria [46][47][48]. In addition, Lens includes more data than both Scopus and WOS [49]. In other words, while both Scopus and WOS only listed publications that are included in their indexed journals, Lens includes more data beyond these two databases. Although Google Scholar might have more data than Lens, it is not as systematic as Lens, and data retrieval for large sets of data from Google Scholar is smooth.
The search was conducted on Saturday, 11 June 2022. There were no language restrictions if titles, abstracts, and keywords were written in English. A limited number of publications were available in other languages, so the results were manually verified. Among the types of publications considered were articles, book chapters, book reviews, and conference proceedings (full papers), including early access publications of these types. The search strings and other specifications for the three databases are listed in Table 3. Scopus ( TITLE-ABS-KEY ( "psycholinguistic*" ) OR TITLE-ABS-KEY ( "psycholinguistics" ) OR TITLE-ABS-KEY ( "psycholinguistic" ) ) AND ( LIMIT-TO (DOCTYPE, "ar" ) OR LIMIT-TO (DOCTYPE, "cp" ) OR LIMIT-TO (DOCTYPE, "re" ) OR LIMIT-TO (DOCTYPE, "ch" ) OR LIMIT-TO (DOCTYPE, "bk" ) ) Saturday, 11 June 2022, 12,172 document results, 1946-2022 WOS "psycholinguistic*" (Title) or "psycholinguistics" (Title) or "psycholinguistics" (Topic) or "psycholinguistic" (Topic) and Articles or Review Articles or Book Chapters or Books or Early Access or Proceedings Papers (Document Types) Saturday, 11 June 2022, 4845 documents, 1985-2022 Lens ( Title: ( AND ( psycholinguistics AND ) ) OR ( Abstract: ( AND ( psycholinguistics AND ) ) OR ( Keyword: ( AND ( psycholinguistics AND ) ) OR Field of Study: ( AND ( psycholinguistics AND ) ) ) ) ) OR ( Title: ( AND ( psycholinguistic AND ) ) OR ( Abstract: ( AND ( psycholinguistic AND ) ) OR ( Keyword: ( AND ( psycholinguistic AND ) ) OR Field of Study: ( AND ( psycholinguistic AND ) ) ) ) ) Filters: Stemming = Disabled Publication Type = (journal article, unknown, book chapter, book, dissertation, conference proceedings article, conference proceedings, preprint) Saturday, 11 June 2022, Scholarly Works (15,551), 1946-2022 We examined how "psycholinguistics" or "psycholinguistic" is used to describe the size and change of research in this field. Thus, the keywords we used did not include any terms specific to a particular age group, type of learner, language, or any other expanding concept since the above keywords returned a large number of publications.

Data Analysis
Analysing the data involved a number of steps. Data from Scopus were initially exported in three formats: Excel sheets for bibliometric analysis, RIS for CiteSpace, and CSV for VOSviewer. To work with CiteSpace, it was necessary to convert the RIS file into a WOS file. In addition, WOS data were extracted in two formats: text files converted to Excel sheets for bibliometric analysis and plain text files for CiteSpace and VOSviewer. Our last step was to obtain Lens data in two formats: CSV for bibliometric analysis and full-record CSV for VOSviewer.
Prior to CiteSpace analysis, duplicate documents were eliminated using CiteSpace and Mendeley. The bibliometric analysis was performed using Excel. Citation reports were generated using Excel and converted into figures.
For scientometric analysis, the software packages were set to the default settings. For each database, separate visualizations were developed, including network visualizations, overlay visualizations, and density visualizations. Each analysis was performed three times for Scoups and WOS: by author keyword, by source, and by author cited. We performed four analyses for Lens: cooccurrence analysis by author keywords, (co)citation analysis by author, (co)citation analysis by source, and (co)citation analysis by document. The following analyses were conducted in CiteSpace for Scopus and WOS: co-citations by document (references), co-citations by cited authors, and occurrence (keywords). Results included narrative summaries, cluster summaries, visual maps, and burst tables.

Result Overview
Presented below are two sections of our results. Bibliometric indicators for psycholinguistics are presented in the first section. Data from Scopus, WOS, and Lens databases were used to calculate the indicators. These bibliometric indicators include publications by year, top 10 countries, universities, journals, publishers, subject areas, and authors. The second section provides scientometric indicators relating to the development of psycholinguistics. CiteSpace and VOSviewer were used to analyse the indicators. Citation and co-citation indicators are included as well as cooccurrence indicators. Since the analysis is based on the title, keywords, abstract and references, they all include this information in English. To avoid bias, this inclusion was neutral regarding published English-language data. Figure 1A-C shows the length of production by year for the three databases. As can be seen, psycholinguistics has experienced a significant increase in knowledge production, reaching its peak in 2019 with 757 publications in Scopus, 419 publications in the WOS, and 929 publications in Lens. The Scopus publication range is 1-757, the WOS is 6-419, and Lens is 1-929. The total documents analysed were 32,586 of which 25,621 were published between 2000 and 2022. All databases have the lowest number of publications in the previous year. Thus, the production of knowledge related to psycholinguistics has significantly increased in the past two decades.

Production of Psycholinguistics Research by Country and University
Figure 2A-C shows the top 10 producing countries for knowledge related to psycholinguistics. As can be seen, the top 10 countries all belong to the Western world except for Russia, which appears in three databases, along with China and Brazil in Lens. Even though these countries dominate the production of psycholinguistics research, contributions extend beyond this list to the countries after the top 10.

Production of Psycholinguistics Research by Journal and Publisher
Figure 4A−D demonstrates the top 10 journals publishing research in psycholinguistics. Several journals include the word "psycholinguistics" or "psycholinguistic" in their titles. There are also other terms close to psycholinguistics, including the word "psychology". An extended list of journals based on publishers is shown in Figure 4D. A few journals are related to medical and health sciences (e.g., Aphasiology), and cognitive science (e.g., Human Cognitive Processing).   Figure 4A-D demonstrates the top 10 journals publishing research in psycholinguistics. Several journals include the word "psycholinguistics" or "psycholinguistic" in their titles. There are also other terms close to psycholinguistics, including the word "psychology". An extended list of journals based on publishers is shown in Figure 4D. A few journals are related to medical and health sciences (e.g., Aphasiology), and cognitive science (e.g., Human Cognitive Processing). Several journals include the word "psycholinguistics" or "psycholinguistic" in their titles. There are also other terms close to psycholinguistics, including the word "psychology". An extended list of journals based on publishers is shown in Figure 4D. A few journals are related to medical and health sciences (e.g., Aphasiology), and cognitive science (e.g., Human Cognitive Processing).    Figure 5A,B shows the list of top 10 publishers for knowledge in psycholinguistics. As Scopus does not include publisher information, these lists are limited to WOS and Lens databases. In terms of publishing research related to psycholinguistics, Springer Nature and Elsevier achieve the top two rankings in both databases.  Figure 5A,B shows the list of top 10 publishers for knowledge in psycholinguistics. As Scopus does not include publisher information, these lists are limited to WOS and Lens databases. In terms of publishing research related to psycholinguistics, Springer Nature and Elsevier achieve the top two rankings in both databases.

Production of Psycholinguistics by Research Area, Keywords, and Cooccurrence
In psycholinguistics, psychology and language are integrated, but they also integrate with other fields (Figure 6A-C). Psycholinguistics is dominated by publications in psychology, arts and humanities, social sciences, and neuroscience, as shown in Figure 6A. According to Figure 6B, linguistics, psychology, neurosciences, and neurology constitute the top four research areas in psycholinguistics. Several of these findings are confirmed in Figure 6C, where psychology, linguistics, psycholinguistics, and computer science are introduced as the four top fields of study in psycholinguistics. Lens shows more specific fields associated with this field of study (e.g., language acquisition, language use, perception, and comprehension).

Production of Psycholinguistics by Research Area, Keywords, and Cooccurrence
In psycholinguistics, psychology and language are integrated, but they also integrate with other fields (Figure 6A−C). Psycholinguistics is dominated by publications in psychology, arts and humanities, social sciences, and neuroscience, as shown in Figure  6A. According to Figure 6B, linguistics, psychology, neurosciences, and neurology constitute the top four research areas in psycholinguistics. Several of these findings are confirmed in Figure 6C, where psychology, linguistics, psycholinguistics, and computer  science are introduced as the four top fields of study in psycholinguistics. Lens shows more specific fields associated with this field of study (e.g., language acquisition, language use, perception, and comprehension).

Production of Psycholinguistics by Authors
It should never be confined to only top authors in the field to contribute to psycholinguistics because any paper published in the field is a contribution. Our goal was to display authors that produced more psycholinguistic knowledge as shown in ( Figure  7A−C). Although the ranking differs according to the database, most of the authors are the same across the three databases. Gibbs [56], who is ranked first in Scopus and WOS, is ranked ninth in Lens. It could be due to Lens' comprehensiveness to include more data compared to Scopus' and WOS' limitation to indexed journals and documents.

Production of Psycholinguistics by Authors
It should never be confined to only top authors in the field to contribute to psycholinguistics because any paper published in the field is a contribution. Our goal was to display authors that produced more psycholinguistic knowledge as shown in (Figure 7A-C). Although the ranking differs according to the database, most of the authors are the same across the three databases. Gibbs [56], who is ranked first in Scopus and WOS, is ranked ninth in Lens. It could be due to Lens' comprehensiveness to include more data compared to Scopus' and WOS' limitation to indexed journals and documents.

Production of Psycholinguistics by Authors
It should never be confined to only top authors in the field to contribute to psycholinguistics because any paper published in the field is a contribution. Our goal was to display authors that produced more psycholinguistic knowledge as shown in ( Figure  7A−C). Although the ranking differs according to the database, most of the authors are the same across the three databases. Gibbs [56], who is ranked first in Scopus and WOS, is ranked ninth in Lens. It could be due to Lens' comprehensiveness to include more data compared to Scopus' and WOS' limitation to indexed journals and documents.

Overview of Psycholinguistics Studies from Scopus, Web of Science, and Lens
In this section, scientometric analysis is presented for the data retrieved from Scopus, WOS, and Lens databases. Psycholinguistics is discussed by highlighting certain concepts, authors, references, and emerging trends.
CiteSpace was used to show the top keywords with the strongest citation bursts for Scopus and WOS data ( Figure 8A,B). All research is represented by the green line. Red

Scientometric Indicators for the Study of Psycholinguistics
Overview of Psycholinguistics Studies from Scopus, Web of Science, and Lens In this section, scientometric analysis is presented for the data retrieved from Scopus, WOS, and Lens databases. Psycholinguistics is discussed by highlighting certain concepts, authors, references, and emerging trends.
CiteSpace was used to show the top keywords with the strongest citation bursts for Scopus and WOS data ( Figure 8A,B). All research is represented by the green line. Red lines indicate the start and end of bursts. The word with the strongest citation burst in Scopus is (support = 229.89) between 1975 and 1995, and (children = 14.72) between 1993 and 2001 for the WOS. There is a variation in the citation burst depending on the database used. WOS contains retrieval, aphasia, deficit, etc., but Scopus only has attention, young adult, procedure, etc. Visualisations of clusters and authors further illustrate these concepts ( Figure 9A−D). Topics like psycholinguistic abilities and eye movement are among the most explored topics in psycholinguistics, as shown in Figure 9A. Figure 9B illustrates more specific concepts, including sentence processing, speech production, and language acquisition. Figure 9C,D shows the most-cited references and the topics searched while citing them. Bilingual language control, ERP correlates, etc., are among these topics (see Figure 9C). Other words included in the WOS database include cortical dynamics, language learning, and naming sentences. (See Figure 9D). It should be noted that next to each cluster, the authors and relevant works are highlighted, and the more intense the text is, the more popular the cluster will be.

Keywords
Year  Visualisations of clusters and authors further illustrate these concepts ( Figure 9A-D). Topics like psycholinguistic abilities and eye movement are among the most explored topics in psycholinguistics, as shown in Figure 9A. Figure 9B illustrates more specific concepts, including sentence processing, speech production, and language acquisition. Figure 9C,D shows the most-cited references and the topics searched while citing them. Bilingual language control, ERP correlates, etc., are among these topics (see Figure 9C). Other words included in the WOS database include cortical dynamics, language learning, and naming sentences. (See Figure 9D). It should be noted that next to each cluster, the authors and relevant works are highlighted, and the more intense the text is, the more popular the cluster will be. It is also important to consider the cooccurrence of keywords used. We generated three visual network maps for the most frequently used psycholinguistic keywords in the three databases using VOSviewer ( Figure 10A−C). Each colour represents a different direction in psycholinguistics. A green topic refers to imaging techniques, a blue one to bilingualism, an orange one to word recognition, and a red one refers to psycholinguistics (see Figure 10A). These colours change according to the database. In Figure 10B, yellow indicates discourse analysis, orange indicates assessment, and green indicates psycholinguistics. Language processing and comprehension keywords are highlighted in red in Figure 10C. It is also important to consider the cooccurrence of keywords used. We generated three visual network maps for the most frequently used psycholinguistic keywords in the three databases using VOSviewer ( Figure 10A-C). Each colour represents a different direction in psycholinguistics. A green topic refers to imaging techniques, a blue one to bilingualism, an orange one to word recognition, and a red one refers to psycholinguistics (see Figure 10A). These colours change according to the database. In Figure 10B, yellow indicates discourse analysis, orange indicates assessment, and green indicates psycholinguistics. Language processing and comprehension keywords are highlighted in red in Figure 10C.  We generated three visual network maps for co-citation and citation by author using VOSviewer ( Figure 11A−C). For each colour, there is a network of co-citations or citations for the authors. The larger the circle, the more co-cited or cited the author is. Similar authors appear in all three databases whether they are co-cited or cited. These include Baayen [57], Chomsky [58], Freiderici [59], Bonin [60], etc. We generated three visual network maps for co-citation and citation by author using VOSviewer ( Figure 11A-C). For each colour, there is a network of co-citations or citations for the authors. The larger the circle, the more co-cited or cited the author is. Similar authors appear in all three databases whether they are co-cited or cited. These include Baayen [57], Chomsky [58], Freiderici [59], Bonin [60], etc.  We generated three visual network maps for co-citation and citation by author using VOSviewer ( Figure 11A−C). For each colour, there is a network of co-citations or citations for the authors. The larger the circle, the more co-cited or cited the author is. Similar authors appear in all three databases whether they are co-cited or cited. These include Baayen [57], Chomsky [58], Freiderici [59], Bonin [60], etc.  We generated three network maps of co-citations and citations by source using VOSviewer ( Figure 12A−C). Colours represent networks of co-citations or citations. Circle size indicates how many times the source has been co-cited or cited. According to Figure  12A, Journal of Memory and Language, Neuroimage, and Journal of Cognitive Neuroscience are the most co-cited sources. Figure 12B shows comparable results using the WOS database with more significant journals (e.g., Brain and Language). The citation network for journals We generated three network maps of co-citations and citations by source using VOSviewer ( Figure 12A-C). Colours represent networks of co-citations or citations. Circle size indicates how many times the source has been co-cited or cited. According to Figure 12A, Journal of Memory and Language, Neuroimage, and Journal of Cognitive Neuroscience are the most co-cited sources. Figure 12B shows comparable results using the WOS database with more significant journals (e.g., Brain and Language). The citation net- The top 10 cited works were extracted from Scopus, WOS, and Lens bibliometric data. Our next step was to merge them and to remove duplicates from them (Table 4). Citations are reported next to each document and whether they were reported in all three databases. Introduction to wordnet: An on-line lexical database [73] 2503 Χ Χ The top 10 cited works were extracted from Scopus, WOS, and Lens bibliometric data. Our next step was to merge them and to remove duplicates from them (Table 4). Citations are reported next to each document and whether they were reported in all three databases.

Clusters
The network is divided into 12 co-citation clusters (Table 5 provides details). The largest 4 clusters are summarized as follows. The largest cluster (#0) has 204 members and a silhouette value of 0.914. It is labelled as affective norm by LLR, individual difference by LSI, and familiarity account (3.15) by MI. The most relevant citer to the cluster is Veldre [85]: "Semantic preview benefit in English: individual differences in the extraction and use of parafoveal semantic information". The network is divided into 20 co-citation clusters (see Table 5 for further details). The largest eight clusters are summarized as follows. The largest cluster (#0) has 131 members and a silhouette value of 0.896. It is labelled as formulaic language by both LLR and LSI and as persistence (1.76) by MI. The most relevant citer to the cluster is Smith [86]: "The effect of word predictability on reading time is logarithmic".

Citation Counts
In Scopus, the third is Baayen [57] in Cluster #3, with citation counts of 54. The fourth is Kutas [87] in Cluster #5, with citation counts of 45. In the WOS, the third is Baayen [57] in Cluster #0, with citation counts of 41. The fourth is Kuznetsova [88] in Cluster #2, with citation counts of 41. Table 6 lists the remaining top authors based on citation counts. In Scopus, the third is Baayen [57] in Cluster #3, with bursts of 24.53. The fourth is Kutas [87] in Cluster #5, with bursts of 20.76. In the WOS, the third is Baayen [57] in Cluster #0, with bursts of 20.62. The fourth is Kuznetsova [88] in Cluster #2, with bursts of 20.30. See Table 7 and Figure 13A,B for the remaining top 10 detected bursts in psycholinguistics.

Centrality
In Scopus, the top ranked item by centrality is Baayen [57] in Cluster #3, with centrality of 58. The second one is Pickering [94] in Cluster #5, with centrality of 46. In the WOS, the third is Warriner [97] in Cluster #1, with centrality of 39. The fourth is Alonso [102] in Cluster #1, with centrality of 38. The remaining top central authors in psycholinguistics are listed in Table 8.

References
Year

Centrality
In Scopus, the top ranked item by centrality is Baayen [57] in Cluster #3, with centrality of 58. The second one is Pickering [94] in Cluster #5, with centrality of 46. In the WOS, the third is Warriner [97] in Cluster #1, with centrality of 39. The fourth is Alonso [103] in Cluster #1, with centrality of 38. The remaining top central authors in psycholinguistics are listed in Table 8.

Sigma
In Scopus, the top ranked item by sigma is Baayen [57] in Cluster #3, with sigma of 0.00. The second one is Pickering [94] in Cluster #5, with sigma of 0.00. In the WOS, the third is Warriner [97] in Cluster #1, with sigma of 0.00. The fourth is Alonso [103] in Cluster #1, with sigma of 0.00. See Table 9 for the remaining authors receiving high attention by researchers in psycholinguistics.

Discussion
The current study sought to assess the evolution of knowledge in psycholinguistics, an interdisciplinary field that studies how language is used and learned [23]. This objective was achieved by tracing the history of psycholinguistics and presenting bibliometric and scientometric indicators for 32,568 documents published over the past 76 years. Two sections were devoted to presenting the results. The first section included bibliometric indicators such as publications by year, the top ten nations, universities, journals, publishers, subject areas, and authors. Indicators for scientometrics, including citation, co-citation, and cooccurrence, were presented in the second section.
The study's key findings include the following seven points: (1) The production of knowledge in clinical linguistics increased in the last two decades, where of 32,586 analysed documents, 25,621 were published between 2000 and 2022. (2) While the U.S. leads in all the three databases, followed by the U.K. and Germany, the situation slightly changes if we consider the top 10 universities rankings. In this case, (3) U.S. universities are superseded by European ones. (4) The top journals publishing in the field are the Journal of Psycholinguistic Research, Psycholinguistics, and Behaviour Research Methods, (5) while Elsevier and Springer Nature are the major publishers. (6) There are a plethora of subject areas related to psycholinguistics. Among these we find psychology, arts and humanities, social sciences, neuroscience, linguistics, and computer science. The last finding (7) shows that Gibbs [56], Pulvermuller [106], and Rickheit [107] are some of the major authors contributing to the field of psycholinguistics.
The second implication refers to identifying patterns and tendencies regarding the structure and dynamics of psycholinguistics-related knowledge. This could be accomplished through co-citation calculation. Importantly, since we analysed more than 32,000 documents containing only the term "psycholinguistic*", clustering was used to organise this massive set of data. In addition, our analysis uncovered the largest co-citation clusters. Among the clusters were individual difference [118], sentence processing [119], formulaic language [120], and Spanish word [121]. Overall, there were 12 clusters summarised as follows:

1.
Examining individual difference in affective norm and familiarity account; 2.
Examining the refractory effect in the role of Broca's area in sentence processing; 3.
Using eye movement to study bilingual language control and familiarity account; 4.
Exploring familiarity account through relative clauses; 5.
The study of formulaic language and language persistence; 6.
Examining affective norm and sub-lexical effect in Spanish words; 7.
The study of persistence through cortical dynamics; 9.
The study of context effect in language learning and language processing; 10. The study of neurophysiological correlates in semantic context integration; 11. Examining persistence as an acquisition norm through naming latencies; and 12. Following a cross-linguistic perspective to study aphasic speakers.
Finding the authors who are frequently cited and have a significant impact on the direction of psycholinguistics research is the third implication. It is obvious that every contribution to the field of psycholinguistics adds to it, but the authors who receive the most citations are likely to have more in-depth knowledge of the subject than less-cited authors. Regarding the most recent works by the authors who receive the most citations, some of them, including Rickheit [107], Herrmann [122], and Brysbaert [91], address general topics such as the history of psycholinguistics [107], language use [122], reading [123], and individual differences [124,125]. Other authors, such as Levelt [3], address more specific topics, including visual word recognition [126], semantic frames [127], bilingualism [128], and grammar learning [129].
The fourth implication corresponds to the most frequently cited publications, which are important sources for psycholinguistics research. The majority of the articles were reviews of scientific literature that covered subjects such as latent semantic analysis [62], dual route cascaded model [71], reading, and word association [84]. A closer look at the identified 24 top-cited documents can lead to two patterns. First, the top-cited documents between 1967 and 2000 included speech perception [77], concreteness [68], psycholinguistic database (e.g., MRC, WordNet) [73,75,81], mental representation [80], retrieval in sentence production [63], word association and mutual information [84], second language acquisition [79], impaired vs. normal word reading [83], cross cultural psychology [69], auditory cortex and silent reading [64], knowledge representation and semantic analysis [62], phonological loop in language learning [82], and learning using the cognitive approach [61]. The second patterns included topics from the top-cited documents published after 2000, and these included topics such as using computational models for visual word recognition and reading [71], functional anatomy of language [70], reading acquisition [78], psycholinguistic models and neurobiological aspects of language [76], sentence production using abstract syntax [66], bilingual language production [67], sentence comprehension [72], word frequency measurement [74], and research in second language acquisition [65].
The final implication has to do with finding authors whose works in psycholinguistics might attract the attention of other authors and speedily become more frequently cited. Sigma metrics were used to calculate this component. Among the most-cited items stand out linear mixed models [57,89], emotional language [97,104], and language production and comprehension [94]. Even though our analysis highlighted assorted topics, they all related to psycholinguistics to some extent. For instance, linear mixed models are necessary to analyse nested data, whereas emotional language and production and comprehension are more related to the use of language in daily situations.

Practical Implications
Researchers should interpret the findings of scientometric studies carefully [130] no matter how popular this research method has become [131,132]. In this study, we retrieved data from multiple sources and avoided limiting ourselves to one database unless it was well-justified (i.e., Scopus, WOS, and Lens). To include various scientometric indicators in the analysis, different tools should be used (for example, both CiteSpace and VOSviewer were used in this study).

Theoretical Implications
There at least two practical implications in this study. The first reason for the elevated level of research in psycholinguistics is due to its integration with the education of languages, which makes it one of the first choices for researchers to explore and examine. There is, however, a need for more experimental and neuroscience-based research that will result in more credible findings of use to society and the advancement of educational psychology and the teaching of languages. Secondly, higher education institutions worldwide need to shift the focus of linguistics studies from their theoretical to scientific aspects. Psycholinguistics courses could be introduced, and even undergraduate and graduate degrees could be granted in the field. Studying theoretical linguistics should be a means to the study of language science, a degree in language sciences that has applied personal, societal, and economic value to the individual and the state.

Limitations
There are at least two limitations to this study. The first limitation pertains to the search string we used to retrieve the data. We searched for several types of documents with "psycholinguistics" or "psycholinguistic" in the title, abstract, author keywords, or topic. While this is justified by our intention to specifically track the usage of the term "psycholinguistics" and to avoid a lengthy paper, the inclusion of other specific topics may have altered these results. For example, we are fully aware that if we conducted a search for "language acquisition", "sentence production", and a variety of other terms, there will be large data sets for each of these search strings. The cluster analysis also has a limitation. Although we were able to cluster more than 32,000 documents into 12 psycholinguisticsrelated patterns, it was beyond the scope of our research to examine and present these clusters in detail.

Conclusions
This study examined the evolution and application of the term "psycholinguistics" over the past seventy-six years. Therefore, we conducted a scientometric study using eight bibliometric and eight scientometric indicators to analyse 32,586 Scopus, WOS, and Lens database documents. CiteSpace and VOSviewer were utilised to visualise and tabulate the analysed data, respectively. The principal findings comprised the presentation of visualisations and tabulations to produce knowledge in psycholinguistics by year, region, institution, journal, publisher, subject area, author, and most-cited documents. For example, of the 32,586 analysed documents, 25,621 were published between 2000 and 2022, indicating a significant increase in the production of knowledge in psycholinguistics over the past two decades. Importantly, we identified the most sought-after keywords, central authors, and those who may in the future receive more citations in the field of psycholinguistics. The grouping of 32,586 documents into 12 clusters demonstrating the major psycholinguistics research patterns is a crucial finding.  Informed Consent Statement: Neither human nor non-human subjects were involved directly in this research. Therefore, informed consent was not required.

Data Availability Statement:
The data presented in this study are available on request from the first author.