## 4 Discussion
### The Impact of Reading Condition and Text Type on Eye Movement Patterns across Age Groups  
First, the AFD, which indicates the speed at which a reader processes a word or a semantic chunk, was analyzed based on age, reading conditions, and text types. The main effect of age showed that, regardless of the reading condition and text type, in general, AFD decreased as age increased. This aligns with the results of previous studies that have explored the relationship between age and fixation duration [47; 48]. Results from the Bonferroni post hoc test, which examined differences in AFD across age, revealed variations depending on reading condition and text type. Age differences in AFD were prominent in the R condition when reading fictional text. When it comes to fictional text, older children tend to quickly extract essential information from the text, while younger children take their time in word reading, including decoding and the interpretation of the information, and read the text attentively when asked to read on their own. The reduced age-related gaps in AFD when reading non-fictional text show that older children invest more time and attention to challenging text with complicated sentence structures, while younger children may employ a different approach to processing such text. These findings are consistent with prior research suggesting that text type and difficulty can affect readers' AFD [49]. Unlike the R condition, under the AR condition, the impact of age was pronounced when reading non-fictional text. Despite not reaching statistical significance, the AFD for older children under the AR condition appeared to be longer than that under the R condition for fictional reading, while the contrast was negligible when reading non-fictional text. When provided with audio assistance for reading fictional text, which is typically an easier and more comprehensible text, older children seem to somewhat synchronize their reading pace with the auditory narration while maintaining their own pace. This reading strategy becomes noticeable from the third grade onward, as indicated by the emergence of a plateau at that point. However, when reading non-fictional text, older children in grades 4 to 6 adopt a faster reading strategy to enhance their comprehension. Second, there is a general decrease in overall TFD with age in both text types, as evidenced by the main effect of age. However, the significance was only exhibited in fictional reading. TFD reflects the time a reader dedicates to comprehensively engaging with the entire text. This age-related trend explains the development of reading fluency as a child grows older [48], and this effect is particularly notable during the reading of fictional text. Furthermore, an interaction effect between age and reading condition was observed, attributed to the substantial drop in TFD observed in grade 1 under the AR condition, unlike the extended TFD observed in the R condition, which could potentially stem from different strategies used by children across age, depending on the reading modalities. In the R condition, TFD tends to decrease with age, irrespective of text type, but the age effect was significant only when reading fictional text. This effect arises due to the reduced TFD among the first graders when engaging with non-fictional text. Typically, when readers encounter difficult text, there is a tendency for the TFD to rise [25]. However, in the case of young children, text covering unfamiliar topics may affect their focus on the text, potentially leading to a decrease in TFD. While under the AR condition, the trend of decreasing TFD with age was observed in fictional reading, similar to that observed for the R condition, the TFD for grade 1 children was the shortest among all age groups, and the difference between two reading conditions among first graders was significant. This suggests that first graders actively take advantage of audio assistance during fictional reading.