Aging and the use of interword spaces during reading: Evidence from eye movements

In an eye movement experiment, we assessed the performance of young (18–30 years) and older (65 + years) adult readers when sentences contained conventional interword spaces, when interword spaces were removed, or when interword spaces were replaced by nonlinguistic symbols. The replacement symbol was either a closed square (■) that provided a salient (low-spatial-frequency) cue to word boundaries, or an open square (□) that provided a less salient cue and included features (vertical and horizontal lines) similar to those found in letters. Removing or replacing interword spaces slowed reading times and impaired normal eye movement behavior for both age groups. However, this disruption was greater for the older readers, particularly when the replacement symbol did not provide a salient cue as to word boundaries. Specific influences of this manipulation on word identification during reading were assessed by examining eye movements for a high- or low-frequency target word in each sentence. Standard word frequency effects were obtained for both age groups when text was spaced normally, and although the word frequency effect was larger when spaces were removed or filled, the increases were similar across age groups. Therefore, whereas older adults’ normal eye movements were substantially disrupted when text lacked conventional interword spaces, the process of lexical access associated with the word frequency effect was no more difficult for older than for young adults. The indication, therefore, is that although older adults struggle from the loss of conventional cues to word boundaries, this is not due to additional difficulties in word recognition.