MacKeben Manfred, Trauzettel-Klosinski Susanne, Reinhard Jens, Dürrwächter Ute, Adler Martin, Klosinski Gunther
The Smith-Kettlewell Eye Research Institute, San Francisco, California, USA.
J Vis. 2004 May 14;4(5):388-402. doi: 10.1167/4.5.4.
We investigated whether dyslexics make instantaneous automatic adjustments of reading saccades depending on word length. We used a single-word reading paradigm on 10 dyslexic and 12 normally reading children aged 11-15 years. Eye movements were recorded by scanning laser ophthalmoscope (SLO) while subjects read single words of different length aloud. All subjects passed standardized prescreening tests, which included a reading test, to exclude those with discernible deficits of eyesight, oculomotor skill, or intellectual development. We measured number, direction, frequency, and amplitude of saccades, as well as the durations of inter-saccadic intervals, as functions of word length. The results show that word length influences the number and amplitude of reading saccades in both subject groups, but this relationship showed quantitatively significant group-specific differences: Both groups showed a gradual increase of the saccade amplitudes in either direction dependent on word length, but the gain of this function was significantly lower in the dyslexics. The durations of holding phases between saccades were significantly longer in the dyslexics, and accordingly, we found a lower rate of occurrence of saccades per unit time in the dyslexics. Forward saccade amplitudes showed no correlation with the duration of the preceding or following holding phases in either group. The data show that the mechanisms enabling dyslexics to make instantaneous adjustments of reading saccades depending on word length are present but quantitatively impaired. This supports the view that these adjustments may help dyslexics to increase reading speed, but that they cannot utilize them to the same extent as normal readers.
我们研究了诵读困难者是否会根据单词长度对阅读扫视进行即时自动调整。我们对10名11至15岁的诵读困难儿童和12名正常阅读儿童采用了单字阅读范式。在受试者大声朗读不同长度的单字时，用扫描激光检眼镜（SLO）记录眼动。所有受试者都通过了标准化的预筛查测试，包括阅读测试，以排除那些有明显视力、动眼技能或智力发育缺陷的人。我们测量了扫视的数量、方向、频率和幅度，以及扫视间隔的持续时间，作为单词长度的函数。结果表明，单词长度影响两个受试组阅读扫视的数量和幅度，但这种关系在数量上显示出显著的组间差异：两组都显示出扫视幅度在任一方向上随单词长度逐渐增加，但诵读困难者的这种函数增益明显较低。诵读困难者扫视之间的停顿阶段持续时间明显更长，因此，我们发现诵读困难者单位时间内扫视的发生率较低。在两组中，向前扫视幅度与前一个或后一个停顿阶段的持续时间均无相关性。数据表明，使诵读困难者能够根据单词长度对阅读扫视进行即时调整的机制是存在的，但在数量上受损。这支持了这样一种观点，即这些调整可能有助于诵读困难者提高阅读速度，但他们无法像正常读者那样充分利用这些调整。
