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Effect of working memory load in natural sentence reading in adolescents with ADHD and ADD- Evidence from the simultaneous recording of Eye Movements and Fixation-Related Potentials
Poster Session D, Saturday, October 26, 10:30 am - 12:00 pm, Great Hall 3 and 4
Jou An Chung2,3, Pei-Chun Chao1, Jie-Li Tsai4, Chia-Ying Lee1,2,3,5; 1Institute of Linguistics, Academia Sinica, Taipei, Taiwan, 2Institute of Cognitive Neuroscience, National Central University, Taoyuan, Taiwan, 3Interdisciplinary Neuroscience, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan, 4Department of Psychology, National Chengchi University, Taipei, Taiwan, 5Research Center for Mind, Brain, and Learning, National Chengchi University, Taipei, Taiwan
Prior studies reported that executive dysfunctions such as deficits in working memory (WM) may explicate reading difficulty in individuals with Attention Deficit／Hyperactivity Disorder (ADHD or ADD). Nevertheless, the extant evidence remained equivocal since most findings relied on the correlation between WM capacity and performance on the offline standardized reading assessments. Hence, this study aimed to examine the effect of WM load on natural reading among ADHD, ADD, and normal controls by simultaneously recoding Eye-Movement (EM) and Fixation-Related ERPs (FRPs). Three levels of WM-load were determined by the varying filler-gap distance. Low WM-load (LWM) condition comprises the sentences with the simplest Chinese Subjective Relative Clause (SRC) ( [FILLER] RC verb (協助/help) + RC noun (居民/resident) + 的(DE) + Head noun [GAP] (志工/volunteer) ). As for the medium and high WM-load conditions, one constituent- adverbial modifier (ex: 熱心/enthusiastically) and two constituents- a locative preposition and an adverbial modifier (ex: (在社區/in the community)+(熱心/enthusiastically)) were added prior to the RC verb, respectively. Fifty-three college students with normal reading, eight ADHD, and eight ADD read 81 sentences at their own pace while EMFRPs were simultaneously recorded. The overall EM patterns revealed that ADHD showed the longest total reading time, the greatest number of total fixations, and most regressions per sentence in each WM-load condition, followed by the ADD and the normal control group. Specifically, in ADHD, the number of regressions accounted for over 70 percent of the total fixations. Compared to normal controls, ADHD and ADD initiated longer and unstable forward and backward saccades. EM patterns on the head noun (HN) where the ambiguity is supposed to be resolved were also compared. ADHD showed longer go-past-time, rereading time, higher rereading rate, regression-in, and regression-out rate, followed by ADD and the normal control. Meanwhile, the EM data from normal control revealed the significant main effect of WM load on first-pass (first fixation duration) and second-pass measures (rereading rate and regression-in rate), indicating the effect of WM load on word recognition and sentence integration. However, the WM load effect was absent in ADHD and ADD. For the FRPs, the Linear Mixed Model analysis result revealed a significant WM effect on the P200, N400, and the late frontal negativity in the normal control group. The HN in the LWM condition yielded greater positivity of the P200 than that in MWM and HWM. Subsequently, the HN in the HWM condition yielded greater negativity of the N400 in the right-parietal region and the late frontal negativity. A higher WM load can lead to effortful word recognition, difficulty in sentence integration, and ultimately results in difficulty in the referential binding process. However, this WM effect on the FRPs has not been found in ADHD and ADD, suggesting that all levels of the WM-load were challenging for them. In sum, current findings demonstrated that the modulations of WM load on sentence comprehension can differentiate three groups.
Topic Areas: Disorders: Developmental, Reading