汉语发展性阅读障碍儿童的快速命名缺陷:副中央凹预视效益小和负荷代价大之争

Explaining RAN Deficit of Chinese Children with Developmental Dyslexia: The Controversy between Parafoveal Preview Benefit and Parafoveal Load Cost

关于汉语发展性阅读障碍儿童的快速命名缺陷存在两种理论争论:副中央凹预视效益小和副中央凹负荷代价大。本研究采用修订的汉字快速命名范式,操纵副中央凹预视和负荷两个变量,记录阅读障碍、年龄匹配以及能力匹配儿童的眼动轨迹,区分两种理论争论。结果发现阅读障碍儿童在副中央凹预视效益量上小于年龄匹配组,但在负荷代价上并无显著差异。结果支持汉语阅读障碍儿童快速命名缺陷源于副中央凹预视效益小,而非负荷代价大的观点。

Rapid automatized naming(RAN) deficit is one of the cognitive deficits of dyslexic in both alphabetic and Chinese languages. Two hypotheses have been put forward to account for the RAN dysfunction in dyslexic: reduced parafoveal preview benefits and increased parafoveal load costs. At present, these two hypotheses have not been distinguished because previous studies have only manipulated one of the two variables in one experiment;However, the manipulations of parafoveal preview and parafoveal load are correlational. The present study tests two hypotheses directly by manipulating the parafoveal load and parafoveal preview in single experiment, in order to distinguish the two hypotheses in terms of the accounts for the RAN deficits of children with dyslexia.The modified RAN paradigm proposal is used. The stimulus set is composed of 28 RAN matrices containing 5 familiar characters. All letters occur equally, and they are pseudo randomly ordered such that there are no immediate repetitions. The spatial arrangement of the traditional 5 × 10-item matrix is modified, such that character items are irregularly spaced within each row. Half the items stand in the right parafoveal span of the preceding item and thus they can be parafoveally previewed(P). The other half stand beyond the parafoveal span of N-1(nP). Half the items are followed by parafoveal inputs at the right(L) and the other half are not(nL). Three groups of children are selected as participants: children with developmental dyslexia(DD), chronological age-matched(CA) and reading level-matched(RL). The parafoveal preview benefit is computed with the formula(non-previewed-previewed)/previewed, indicating the proportion of the fixation time for previewed items(PL+PnL) that is additionally required when looking at items with no preview(nPL+nPnL). Similarly, the parafoveal load cost is computed as the proportion of the fixation time for non-loaded items(PnL+nPnL) that is additionally required when there is a parafoveal load(PL+nPL). The formula is(loaded-non-loaded)/non-loaded.All three groups of children show significant parafoveal preview benefit for the measure of gaze duration(ts > 4.43, ps <.001), but the amount of preview benefit across three groups do not reach significance. The significant effect on the measures of total fixation time is only observed for agematched children(t(14) = 4.70, p <.001). For the amount of parafoveal load, there are no significant differences across three groups of children for measures of gaze duration and total fixation time. These results above indicate that Chinese dyslexia children show less parafoveal preview benefit than age-matched children, but parafoveal loads are not significant between the two groups. The present study yields robust evidence, supporting the first account of RAN deficit, that the parafoveal dysfunction of Chinese dyslexia children is due to their reduced parafoveal preview benefits.