Reading with filtered fixations: Adult age differences in the effectiveness of low-level properties of text within central vision.

Abstract

The ability to read is crucial for functioning effectively in everyday life. However, numerous studies indicate that many aspects of reading performance differ between young adults (aged 30 years and under) and older adults (aged 65 years and over; e.g., Kliegl, Grabner, Rolfs, & Engbert, 2004; Rayner, Castelhano, & Yang, 2009;Rayner, Reichle, Stroud, Williams, & Pollatsek, 2006; see also Laubrock, Kliegl, & Engbert, 2006) and these differences are widely attributed to normal sensory and cognitive decline. But the precise nature of the differences in reading performance that occur as adults reach older age has yet to be fully determined.Of particular importance is that the eyes move when reading and make a series of brief fixational pauses, with the effect that different areas of text can be viewed within central vision (an area approximately 2° wide around the point of fixation; for a review, see Rayner, 2009).Crucially, during these pauses, the visual system acquires only low-level visual properties from text and these visual properties then provide the bases for the subsequent linguistic analyses that ultimately allow readers to make sense of what they are seeing (e.g., Allen, Smith, Lien, Kaut, & Canfield, 2009;Lovegrove, Bowling, Badcock, & Blackwood, 1980;Patching & Jordan, 2005a, 2005b. Indeed, the low-level properties of text falling within central vision provide a range of different scales of visual analysis (spatial frequencies) that are associated with different aspects of the text being read. So, for example, lower spatial frequencies allow readers to see a word's coarse overall shape but not its fine detail, whereas higher spatial frequencies allow readers to see a word's fine detail, such as the precise form of individual letter features (e.g., Allen et al., 2009;Jordan, 1990Jordan, , 1995Kwon & Legge, 2012;Legge, Pelli, Rubin, & Schleske, 1985; Patching & Jordan, 2005a,b). Thus, although spatial frequency analyses in central vision are unlikely to be apparent to the reader, reading relies fundamentally on these low-level visual properties of text. But it is unclear whether the effectiveness of spatial frequencies within central vision shown by young adults remains unaltered in older age. Of particular significance is that normal aging produces a characteristic decline in sensitivity to various scales of spatial frequency, especially to higher spatial frequencies within central vision, due to a combination of optical changes and changes in neural transmission (for discussions, see Derefelt, Lennerstrand, & Lundh, 1979;Elliott, 1987;Higgins, Jaffe, Caruso, & deMonasterio, 1988;Laubrock et al., 2006;Owsley, 2011). As a result, older adults may be less able than young adults to process the visual detail of text falling within central vision during fluent reading, and this change may affect reading performance. Indeed, it is widely assumed that reading relies greatly on visual detail from within central vision (e.g., Engbert, Nuthmann, Richter, & Kliegl, 2005;Reichle, Rayner, & Pollatsek, 2003; see als...

The effects of interword spacing on the eye movements of young and older readers

“…These findings are consistent with findings from previous studies (e.g. Kliegl et al, 2004;McGowan et al, 2014;Paterson et al, 2013a;Rayner et al, 2006).…”

“…Accordingly, the present experiment sought to address these issues by examining how the eye movements of young and older adults were affected by changes in the size of the spaces between words when reading. These findings will extend those reported by McGowan et al (2014) and Rayner et al (2013) by more fully revealing how well young and older adults' reading performance adjusts to changes in spatial information in text.…”

“…This may mean that older adults rely especially heavily on interword spaces during reading as these provide coarse-scale cues for word segmentation and reduce the crowding of the exterior letters of words. Consistent with this account, McGowan et al (2014) reported that filling interword spaces with closed squares (■), which provide a coarse-scale cue to word boundaries, resulted in a much smaller age difference in eye movement behaviour than filling interword spaces with open squares (□). The open squares did not provide a particularly salient cue to word boundaries and included features similar to those found in letters (horizontal and vertical lines) and so were likely to produce greater effects of visual crowding.…”

“…The studies by McGowan et al (2014) and Rayner et al (2013) clearly show that older adults are more sensitive than young adults to the availability of spatial information in text. Of course, in normal reading (of English at least) unspaced text is not usually encountered.…”

“…We had no prior expectations as to whether these subtle changes in interword spacing size would be beneficial or disruptive to the reading of young adults. However, given that older adults experience greater effects of crowding (Scialfa et al, 2012), and have an increased reliance on coarse-scale cues for word segmentation (McGowan et al, 2014), it was expected that this age group may benefit from the reduction in crowding and the provision of an even more salient cue for word segmentation that expanded interword spaces would afford. Furthermore, as older adults may have a smaller perceptual span (Rayner et al, 2009), the potential cost of reduced parafoveal processing when interword spaces are expanded may be reduced for this age group.…”