The Effect of Age and Language Structure on Working Memory Performance

The Effect of Age and Language Structure on Working Memory Performance Klara Marton (kmarton@brooklyn.cuny.edu) Department of Speech Communication Arts & Sciences, Brooklyn College, City University of New York 2900 Bedford Ave., Brooklyn NY, 11210 USA Richard G. Schwartz (RSchwartz@gc.cuny.edu) Ph.D. Program in Speech & Hearing Sciences, The Graduate Center of City University of New York, 365 Fifth Avenue, New York, NY 10016 Aviva Braun (Avivaeb@msn.com) Department of Speech Communication Arts & Sciences, Brooklyn College, City University of New York 2900 Bedford Ave., Brooklyn NY, 11210 USA Abstract This study examined the effect of age and language structure on working memory (WM) performance in three groups of participants (7;0-8;6 9;6-11:00; 19-22 years). The findings suggest that both age and language structure have an impact on WM performance. There was an interaction between these two factors that resulted in differences in performance pattern and error type. The measures of the storage function were influenced by the length of the stimuli, whereas processing efficiency was affected by sentence complexity. Keywords: working memory, executive functions, language comprehension, developmental study Working memory (WM) and executive functions There is a strong relationship between WM and executive functions across age groups and populations. WM span measures predict language comprehension (Engle & Kane, 2004). In recent years, significant individual and developmental differences have been explored in WM performance. These findings resulted in a conceptual debate regarding resource sharing. A variety of unitary and semi- unitary models (e.g., Conway & Engle, 1996; Cowan, 1997, Just & Carpenter, 1992) have been developed that challenged Baddeley's multicomponent theory (Baddeley, 1986). WM capacity tasks became closely tied to measures of attention control in contexts that involve distraction or interference (Feldman Barrett, Tugade, & Engle, 2004). A number of researchers have found a close relationship between individual differences in WM capacity and general executive functions (e.g., Conway & Engle, 1994; Engle & Cane, 2004). WM span was constrained by controlled attention (Engle, Kane, & Tuholski, 1999), by task switching ability (Towse, Hitch, & Hutton, 1998), and by the inhibition of irrelevant information (Hasher & Zacks, 1988). According to Baddeley's model, participants may demonstrate individual variations in processing and storage independently from a general executive capacity in complex WM span tasks (Bayliss, Jarrold, Gunn, & Baddeley, 2003). The extent to which performance on complex WM span tasks depends on processing and storage functions is still subject to debate (see more detailed conceptual reviews of WM e.g., Baddeley, 2000; Engle & Kane, 2004; Miyake & Shah, 1999). Developmental studies on WM performance evidenced that executive functions develop gradually until adolescence (DeLuca, Wood, Anderson, Bucanan, Proffitt, Mahony, & Pantelis, 2003). WM span development reflects a combination of various factors, such as the efficiency and speed of processing. Older children perform faster on the same tasks as younger children therefore, they need fewer resources to perform the required activity (e.g., counting) and have more resources available for memory operations (Case, Kurland, & Goldberg, 1982). A different interpretation of age-related changes is provided by the task- switching model (Towse & Hitsch, 1995). In linguistic span tasks, participants may use the sentence context to help reconstruct the list of words that have to be remembered. If this reconstitution process is difficult, it may take so much time that some information could be lost. Younger children may make more errors because of difficulty in attention switching. In complex WM tasks, span measures may reflect the ability to control/switch attention, whereas response times depend on retrieval speed (Hitsch, Towse, & Hutton, 2001; Kail & Salthouse, 1994). Barrouillet & Camos (2001) suggest that increases in attentional capacity and better attention switching result in developmental increases in WM span. The present study examined whether developmental differences in WM support the theory of WM capacity and executive attention (Engle & Kane, 2004). According to this theory, individual differences in WM capacity are not about memory storage per se, but reflect executive control, the ability to maintain goal-relevant information in a context of interference. Therefore, WM measures reflect multiple