7. Discussion
As predicted in the first hypothesis, the results show that (a)similar to their adult counterparts (Kasisopa et al., 2013), children have a preferred viewing location just left of the word-centre as a product of the relative frequency of word-boundary characters and (b) the older children’s landing sites are closer to word centre than are the younger children’s, and thus the older children’s results are more similar to the adults. The differences between these two groups of children may be due to different reading materials, age, and/or educational achievement of the participants in this study. However, and in accord with the second hypothesis, in both groups, it was only the first and not the last character frequency that affected children’s landing site. First character frequency also had facilitative effects on first fixation, single fixation, and gaze duration, and last character frequency did provide some facilitation on single fixations by the older children, and on gaze duration, but only when text was spaced. Spacing generally played a potentiating role; it potentiated the effect of first character frequency on the PVL in the landing site results, it enabled firstcharacter frequency effects on first fixation, and it potentiated the effect of last character frequency on gaze duration. However, in contrast to what was expected from hypothesis three, it is not that case that (a) for children, especially the younger ones, spacing has a more powerful on eye movements than does the effects of character frequency especially for the younger children, and (b) that boundary characters affect eye movements and fixation patterns only when children are forced to use these cues, i.e., in the absence of spaces. Rather it appears that spaces potentiate children’s in learning to use boundary character frequency effects to aid word segmentation. The results of this study support the findings by Reilly et al. (2005) and Kasisopa et al. (2013) that the effective saccade target for Thai readers is the word-centre, with the mean landing sitefor first rightward incoming saccades just left of centre. Moreover, the results here show that this is the case even for Thai children; characters that are diagnostic of word boundaries to help children to target word centres effectively. The presence of high frequency first characters serves to push the landing site further into the word and also tends to shorten viewing times (first character for first fixation, and both first and last character for single fixation and gaze duration.). This means that Thai readers learn to use
position-specific relative frequency of character in the first and last positions efficiently in guiding their eye movements from a young age. The fact that this study also showed a significant interaction of overall word frequency with landing site, single fixation and gaze duration suggests that both global word features and boundary characters come into play in reading Thai. A comparison of the children’s results here and the adults’ results (Kasisopa et al., 2013) allow us to build a relatively comprehensive account of the development of eye movements and fixation patterns in Thai readers. At least by Grade 6 children are able to use first character frequency to guide eye movements to a PVL similar to their adult counterparts and also similar to their counterparts reading spaced scripts. The use of this cue is most evident when there are spaces between words and with higher word frequency. Similarly, first character frequency assists in lowering first fixation duration and spaces help in this. First character frequency also assists single fixations and last character also plays a role and is facilitated by higher word frequency. Last character frequency also facilitates lower gaze durations and spacing facilitates this. So it can be concluded that children use first character frequency early in reading Thai and this is scaffolded by spacing and word frequency. Last character frequency appears to be a later development, and
again its use is scaffolded by spacing and word frequency. The increased use of last character frequency over age from 6th to 7th Grade to adulthood may well be a result of the complexity of grapheme-to-phoneme of the last characters in Thai. As the reading skills of the readers increase the ability to use the complex grapheme-to-phoneme mapping rules of the last characters also increases. By adulthood Thai readers are using first and last character frequencies to guide eye movements to the PVL and optimize viewing patterns. Comparing these results with those of readers of spaced scripts, it appears that the position of the PVL appears to be relatively consistent across alphabetic languages, despite such gross differences as whether there are spaces between words or not. More generally,
it appears that in the absence of spacing between words (and even if there is spacing between words) experienced readers of a scriptio