Top Lang Disorders Vol. 33, No. 3, pp. 190–207 Copyright c 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins The Language, Working Memory, and Other Cognitive Demands of Verbal Tasks Lisa M. D. Archibald Purpose: To gain a better understanding of the cognitive processes supporting verbal abilities, the underlying structure and interrelationships between common verbal measures were investigated. Methods: An epidemiological sample (n = 374) of school-aged children completed standardized tests of language, intelligence, and short-term and working memory, as well as nonstandardized measures of grammaticality judgment, rapid naming, and sentence recall. Results: Results of a principal component analysis revealed 4 factors corresponding to domain-general working mem- ory, language processing, phonological short-term memory, and fluid reasoning. In corresponding analyses based on younger and older halves of the data, more variables loaded on the fluid rea- soning factor for the younger group, and more task variance was explained by the language or phonological storage factors for the older group. The language processing factor correlated with all of the nonstandardized measures, whereas rapid naming was additionally correlated with work- ing memory. Discussion/conclusions: Separable cognitive processes influence performance on common verbal measures, which has implications for assessment and intervention of children with developmental language impairments. Key words: intelligence, short-term memory, spe- cific language impairment, working memory ERBAL ABILITIES are measured in a logical information, and identify similarities V variety of ways, such as by asking people between verbally presented items. The to follow verbal directions, remember phono- cognitive processes proposed to underlie thesetasksareamatterofsomedebate.Some would argue that these verbal tasks tap a uni- tary language processing factor (MacDonald & Christiansen, 2002), whereas others have Author Affiliation: School of Communication Sciences and Disorders, Western University, London, suggested that these measures place demands Ontario, Canada. on various cognitive processes such as work- This work was supported by a Natural Sciences and ing memory (Alloway, Gathercole, Willis, & Engineering Research Council of Canada Discovery Adams, 2004) and crystallized knowledge Grant and an Academic Development Fund Grant from (McGrew, 2005). This study aimed to con- Western University. The valuable assistance of par- ticipating school personnel and families is gratefully tribute to understanding of the cognitive acknowledged. processes supporting verbal abilities by inves- The author has indicated that she has no financial and tigating the underlying structure and interre- no nonfinancial relationships to disclose. lationships among common verbal measures. Supplemental digital content is available for this article. Direct URL citations appear in the printed MEASURES OF LINGUISTIC ABILITY text and are provided in the HTML and PDF ver- sions of this article on the journal’s Web site (www. topicsinlanguagedisorders.com). One set of verbal tasks comes from those who are studying language and language dis- Corresponding Author: Lisa M. D. Archibald, PhD, School of Communication Sciences and Disorders, orders. The measures are aimed at assess- Elborn College, Western University, London, Ontario, ing core language ability, including the rules Canada, N6G 1H1 ([email protected]). for governing the content of language rep- DOI: 10.1097/TLD.0b013e31829dd8af resented in the semantic or meaning-based 190 Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Cognitive Demands 191 system, and rules for governing the form tense, Pinker (1999) suggested that irregu- of language, including the phonological sys- lar words (e.g., drank) are stored directly tem for representing language sounds and the with their associated meaning whereas regu- morphosyntactic system for combining part lar words (e.g., jumped) must be constructed words, words, and sentences. The rules per- using morphological rules (e.g., add “ed”). taining to language use also may be targeted Consistent with this “words and rules” ac- in some tasks. Traditional tests of core lan- count is evidence of processing differences guage abilities include measures of the abil- in word retrieval tasks requiring or not re- ity to understand language known as recep- quiring the application of a linguistic rule tive language and the ability to produce lan- (Ullman et al., 1997). A preponderance of ev- guage known as expressive language. Recep- idence from connectionist models, however, tive language measures include tasks such as suggests that a single mechanism based on sta- following directions (e.g., “touch the third cir- tistical learning alone is sufficient to account cle and the first black square”) and choosing for the data (Joanisse & Seidenberg, 1999; one of several pictures corresponding to a Rumelhart & McClelland, 1986). Indeed, Bates given word or sentence. Expressive language and Goodman (1997) suggested that gram- tasks include creating a sentence using a given mar and the lexicon were inseparable; they word and completing a sentence using a word proposed a unified lexical account to explain with obligatory morphological markers to cor- a wide body of evidence pertaining to chil- respond to a picture. dren’s emergence of grammar and language The extent to which language tasks de- disorders in older children and adults. Simi- signed to assess semantic, phonological, and larly, Tomblin and Zhang (2006) reported that morphosyntactic knowledge tap a single or a one-dimensional model was sufficient to ac- multiple language processing factor(s) has count for the variance in omnibus language been assessed in only a few studies. Factor test performance, especially for younger chil- analytic studies of standardized tests of lan- dren. These latter findings, then, would pre- guage abilities have reported multiple fac- dict that a single language processing factor tors to explain the variance underlying per- would be sufficient to explain the variance formance (McKay & Golden, 1981; Skarakis- in performance on verbal tasks tapping mor- Doyle, Miller, & Reichheld, 2000). The Clin- phosyntactic or semantic knowledge. It must ical Evaluation of Language Fundamentals be noted, however, that the semantic system (CELF-4; Semel, Wiig, & Secord, 2003) is a encompasses more than just word meaning. standardized test commonly used in clinical It may be that, with a sufficiently compre- practice to identify language and communi- hensive assessment, semantic knowledge it- cation disorders in children. Studies based self may be shown to consist of separable on the normative sample for this test (Semel components. et al., 2003) identified a core language com- posite with four subfactors: expressive lan- MEASURES OF IMMEDIATE MEMORY guage, receptive language, language content, and language structure (or language memory Another group of verbal tasks have been in older groups). Importantly, the CELF-4 is designed by researchers interested in work- an omnibus language test with multiple sub- ing memory, which can be defined as the tests aimed at sampling not only syntactic and ability to hold information in the current semantic knowledge but also all aspects of focus of attention. According to the tripar- language functioning. tite working memory model of Baddeley and In other work, considerable debate sur- Hitch (1974), domain-specific phonological rounds the question of the separability of mor- and visuospatial short-term memory stores phosyntactic and semantic knowledge specif- hold relevant material for brief periods of ically. Using the example of English past time and have a rehearsal mechanism to Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 192 TOPICS IN LANGUAGE DISORDERS/JULY–SEPTEMBER 2013 increase retention (Baddeley, 1986, 2003; tion to a greater extent than verbal short-term Logie, 1995). The third component of work- memory tasks, especially in younger children ing memory is the central executive, a (Alloway, Gathercole, & Pickering, 2006). As capacity-limited domain-general resource as- well, executive functions have been found to sociated with attentional control, high-level support visuospatial tasks when the presen- processing activities, and the coordination of tations involve dynamic rather than static im- activities within working memory (Alloway ages (Logie, 1995). et al., 2004; Baddeley, 1998; Baddeley, Della Salla, Gray, Papagno, & Spinner, 1997). Verbal MEASURES OF INTELLIGENCE tasks such as immediate recall of words or dig- its in a list would be considered to tap phono- A final set of verbal tasks to be consid- logical short-term memory, whereas nonver- ered in this article comprises those that are bal tasks that involve recall of locations, such included in tests of intelligence (IQ). Tests as dots on a grid, would be considered to tap of intelligence traditionally have included in- visuospatial short-term memory. dicators of the ability to analyze information In addition to short-term retention of ma- and solve problems using language-based rea- terial, working memory tasks require addi- soning (verbal IQ) or nonverbal reasoning tional processing of information. Examples of (performance IQ). Alternatively, largely anal- verbal working memory tasks include judg- ogous indicators of crystallized and fluid in- ing the veracity