The Effects Of Foveated Word Frequency And Sub-foveal Word N+1 And Word N+2 Preview On Saccade Target Selection In The Elderly

In Chinese reading,older readers show longer fixation duration,shorter forward saccade length and lower skipping probability,which was called cautious reading strategy by researchers,and it may be related to the difficulty in saccade target selection for older readers.Then,foveal load and parafoveal processing play important roles in eye movement control,and both of them affect saccadic planning for Chinese readers.Some researchers found that,compared with younger readers,the foveal and parafoveal processing capacity of older readers declined.In this case,will foveal load and parafoveal processing still work in saccade target selection for older readers? What's the relationship between them,interactly or independently? This study made an attempt to explore these problems,using boundary paradigm,and to reveal the reason why older readers adopt the cautious reading strategy.In Experiment 1,we selected two-character words with different frequency as foveal words(low load: high frequency;high load: low frequency),and manipulated the preview types(identical and pseudocharacter)of the parafoveal character N+1,to investigate whether the foveal load and the preview of parafoveal character N+1 affect the saccade target selection for older readers and the relationship between the two.Results showed that:(1)Both the frequency of the foveal word and the preview of the parafoveal character N+1 affected the saccade target selection for older readers.And the two worked independently.(2)Compared with younger readers,the progressive-saccade length for older readers was less affected by parafoveal character N+1 preview.These results indicate that the ability of older adults to adjust saccadic planning by parafoveal preview is weakened.Experiment 2 manipulated the foveal word frequency(high frequency and low frequency)and the parafoveal character N+2 preview type(identical and pseudocharacter),to further investigate the relationship of the foveal load and the parafoveal processing in saccade target selection for older readers.Results showed that:(1)Both the foveal word frequency and the parafoveal character N+2preview affect the saccade target selection for younger readers.And the two worked independently.(2)The effect of the parafoveal character N+2 preview on the saccade target selection for older readers was modulated by the frequency of the foveal words.In the case of high-frequency words in the fovea,the progressive-saccade length of older readers was affected more significantly by character N+2 preview than in the case of low-frequency words.The results show that the process of adjusting saccadic planning for older readers using the parafoveal character N+2 preview was more restricted by the foveal load.To sum up,the following conclusions can be drawn:(1)Foveal and parafoveal information processing affect saccade target selection for older readers.(2)Parafoveal character N+1 processing's relationship with foveal load in saccade target selection for older readers is different from the character N+2's.Foveal load and parafoveal character N+1 processing work independently in the saccadic planning.Moreover,the foveal load modulates the effect of the character N+2processing on saccade target selection for older readers.(3)The decline of the parafoveal processing ability is one of the main reasons for older Chinese readers to adopt the cautious reading strategy.