Effects Of Spatial Frequency On Chinese Older Adults’ Reading

Reading is one of the most important skills in our daily life.But as normal aging,as a result of changes on visual ability and cognition function,compared to the young adults,older adults experience particular difficulties during reading(Rayner,Reichle,Stroud,Williams,&Pollatsek,2006;Rayner,Yang,Castelhano,&Liversedge,2011;Rayner,Yang,Schuett,&Slattery,2013).Evidences from alphabetical language research show that impaired lexical processing plays an important role in reading difficulties experienced by older adults(Stine-Morrow,Miller,&Hertzog,2006;Thornton&Light,2006).In addition,older adults from alphabetic languages trend to employ a more "risky" reading strategy to compensate their poorer processing of text(Rayner et al.,2006,2011,2013).However,only a few of studies have examined adult aging differences during Chinese reading,and little has known about how and why word identification changes as normal aging in Chinese.Therefore,in the present studies,we examined adults age differences during Chinese reading.Lexical decision tasks and sentences reading tasks were used in the present studies to investigate adult aging differences during Chinese script processing from both the word recognition level and the sentence reading level.We manipulated the spatial frequency(removed some visual details)of the target words,and then controlled the lexical frequency and visual complexity of target words separately in order to examine young and older adults’lexical processing and visual processing while they were reading.We discussed these findings in relation to possible causes for the reading difficulties experienced by older adults.Lexical decision tasks were used in Study 1.We recruited young and older Chinese readers,and manipulated the lexical frequency(high frequency,low frequency;Experiment la)or visual complexity(high visual complexity,low visual complexity;Experiment lb)of the target words.For the first time,we examined aging effects during single word identification task in Chinese,and word frequency effects and visual complexity effects for readers from different age groups.In Study 2,we further manipulated the spatial frequency to examine word frequency effect(Experiment 2a)and visual complexity effect(Experiment 2b)on young and older adults.Spatial frequency was controlled using an advanced stimulus degradation technique.Stimuli used in Study 2 were the same as in Study 1.Different from Study 1 and 2,Sentence reading tasks were employed in Study 3,and an eye tracker was used to record young and older adults’ eye movements while they were reading sentences.We manipulated word frequency in Experiment 3a and visual complexity in Experiment 3b.Again,effects of spatial frequency obersved on young and older readers were examined.Given that studies form alphabetical languages have shown that parafoveal processing is less efficient for the older than the young adults,and this may attribute older adults’ reading difficulties they experience.Therefore,in Study 4,we manipulated the spatial frequency for parafoveal upcoming words,by using a novel incremental revealing text paradigm(Experiment 4a and Experiment 4b),to further investigate reading difficulties experienced by Chinese older adults.R-Studio software and advanced linear mixed-effects models(LMMs)were used for all data analyses in the present studies.The conclusions are:1)There are aging related word recognition difficulty in lexical decision tasks in Chinese.2)Compared to the young adults,the older adults experienced greater difficulty to processing low frequency and high visual complexity words which indicats that both lexical processing and visual processing are impaired for the older adults.3)Compared to the young adults,the older adults are more vulnerable to the impaired spatial frequency.4)Reduced spatial frequency interrupts both the lexical and visual processing during sentence reading.However,greater spatial frequency effects showed by the older adults was not due to the greater difficulties on lexical processing they experienced.5)Parafoveal processing is impaired for the older adults and this may be an important cause for their reading difficulties.6)Chinese older adults do not adopt a more risky reading strategy,instead,they employ an more caution strategy during reading.