242
PROCEEDINGS of the HUMAN FACTORS AND ERGONOMICS SOCIETY 47th ANNUAL MEETING—2003
AGE-RELATED DIFFERENCES IN READING TEXT PRESENTED WITH
DEGRADED CONTRAST
Tracy L. Mitzner & Wendy A. Rogers
Georgia Institute of Technology
Atlanta, Georgia
Reading is a daily activity for most individuals. Unfortunately, people frequently read in sub-optimal
conditions (Charness & Dijkstra, 1999), which can degrade the perceptual quality of the text, such as
reading a book in inadequate lighting or reading an electronic display in direct sunlight. Degraded text may
affect older adults to a greater extent than younger adults because of age-related vision declines. However,
readers may be able to compensate for text that is difficult to perceive by taking advantage of contextual
information contained in language. This study examined age differences in this reading strategy, by
comparing words that were highly predictable from their sentence context to words that were less
predictable. In addition, text was presented in three levels of texthackground contrast (high, medium, low)
to explore the effects of contrast reduction. The fmdings of this study have implications for designing
printed materials that facilitate reading for older adults.
INTRODUCTION
Reading problems can have a significant
impact on one’s well-being and quality of life.
Reading is a common pastime activity and
proficient language comprehension is important for
many household activities, such as reading bills and
other mail, and for activities related to maintaining
independence, such as reading instructions.
Moreover, if some types of materials are misread,
such as medical instructions and warning labels,
negative consequences could result for one’s health.
The significance of reading in everyday life
warrants human factors research geared toward
understanding the variables that can influence
language processing.
Research has demonstrated that aging is one
factor that affects language processing. Older
adults have greater difficulty understanding and
remembering text they have read, compared to
younger adults (e.g., Hartley, 1993; Kemper &
Kemtes, 2000; Wingfield & Stine Morrow, 2000).
One explanation for age-related reading difficulties
is that older adults may not spontaneously process
information to the same extent as younger adults
(Craik & Byrd, 1982). While some research
findings are consistent with this explanation (e.g.,
Rabinowitz, Craik, & Ackerman, 1982), other
research suggests that under certain conditions older
adults process information to a greater extent than
younger adults. Specifically, a few studies have
found that older adults rely more heavily than
younger adults on contextual information contained
in text when the text is visually degraded (Madden,
1988; Mitzner, 2002, Speranza, Daneman, &
Schneider, 2000). The findings from these studies
suggest that older adults rely on context to a greater
extent than younger adults to compensate for
perceptual degradation.
The previous studies that manipulated
stimulus quality to explore context effects used
various forms of stimulus degradation. Madden
(1988) and Mitmer (2002) inserted asterisks to
degrade target words and Speranza et al. (2000)
used Gaussian noise maskers. These forms of text
degradation are useful to language researchers
because they can be used to interrupt or slow
language processing at a particular stage (i.e., word
recognition) to investigate basic language processes.
However, these forms of text degradation do not
occur in everyday reading situations and, therefore,
the findings of these studies may not generalize to
more ecological forms of stimulus degradation.
Some forms of text degradation do occur in
everyday life. In fact, research has found that
people often read in sub-optimal conditions
Downloaded from pro.sagepub.com at PENNSYLVANIA STATE UNIV on September 13, 2016
PROCEEDINGS of the HUMAN FACTORS AND ERGONOMICS SOCIETY 47th ANNUAL MEETING—2003
(Chamess & Dijkstra, 1999). One form of text
degradation that commonly occurs is poor contrast
between text and the background on which it is
presented. In some situations, poor contrast results
from sub-optimal text design choices, such as
printing dark text on a dark background. In
addition, the quality of the viewing environment can
affect texthackground contrast. For example, the
displays of automatic teller machines, personal data
assistants, and cellular phones, present text that can
be difficult to perceive due to poor contrast,
particularly in certain lighting conditions. In light
of the findings that some forms of text degradation
affect the reading strategies of younger and older
adults differentially, the purpose of this study was
to explore the effects of contrast reduction on
younger and older adults’ utilization of context.
METHOD
Participants
Forty younger adults ranging in age from 19
- 24 years of age (MY= 20, SEy= .19) and 40 older
adults ranging in age from 62 - 79 years of age (Mo
= 7 1, SEo = .53) were recruited to participate in this
study. Participants were screened to exclude nonnative English speakers and those with uncorrected
vision problems (e.g., acuity below 20/40) and
health conditions that affect vision, such as diabetes
and uncontrolled blood pressure.
Materials
Forty-two experimental sentences (Rayner
& Well, 1996) previously normed by
Schwanenflugel (1986) were dispersed within 120
filler sentences; the filler sentences were designed
to resemble the experimental items. Half of the
experimental sentences were presented with a lowpredictability target word and half were presented
with a high-predictability target word. Target
words were matched for length and frequency.
Although all participants were presented with the
same 42 sentence frames, the predictability of the
target word within a particular sentence was
counterbalanced across participants. An example of
a sentence frame is, “The picnic was spoiled
243
because of the
so it was rescheduled.” In the
high-predictability condition the word “rain” would
complete the sentence and in the low-predictability
condition the word “wind” would complete the
sentence.
To manipulate contrast, one-third of the
experimental sentences were presented with high
contrast (text = 32 fL,background = .07 fL),onethird condition with medium contrast (text = 4.3 &,
background = .07 fL), and one-third with low
contrast (text = varied on individual basis,
background = .07 fL). The luminance of the low
contrast condition was determined by each
participant’s performance on a letter identification
task in which contrast was systematically reduced.
Specifically, luminance for the low contrast
condition was the luminance of the lowest level at
which participants could correctly identify all 5
letters in the letter identification task (MY= .18 fL,
SDy=.001 and Mo = .38 fL,SDo=.16).
Word predictability and contrast condition
order was randomized across participants.
Comprehension questions followed each target
sentence.
Procedure
When participants arrived, they were asked
to complete an informed consent and a demographic
questionnaire. Next, the Shipley Vocabulary Scale
(1986), a near acuity test, the Pelli-Robson Contrast
Sensitivity Chart (1988), and Wechsler’s (1 997)
Digit Span Backwards task were administered, in
that order.
For the reading task, participants were
seated approximately 40 cm in front of a computer
monitor and their heads were stabilized with a
chinrest. They were presented with the letter
identification task and then the self-paced reading
task, in which participants read single sentences,
which were presented word-by-word using a
moving window technique.
After the reading task, participants were
given Wechsler’s (1997) Digit-Symbol Substitution
task and Daneman and Carpenter’s (1980) Reading
Span measure. After participants finished the
experiment, they were debriefed and paid for their
time (older adults) or they were given credit
(younger adults).
Downloaded from pro.sagepub.com at PENNSYLVANIA STATE UNIV on September 13, 2016
I
244
PROCEEDINGS of the HUMAN FACTORS AND ERGONOMICS SOCIETY 47th ANNUAL MEETING—2003
RESULTS
Older adults reported having attained a
higher education level than younger adults reported,
F( 1,79) = 11.OO, p < .O 1. However, younger adults
performed better than older adults on Digit Span
Backwards, F(1,79) = 4 4 . 5 4 , ~
< .01, Digit-Symbol
Substitution, F( 1, 79) = 69.79, p < .01, and Reading
Span, F(1,79) = 1 2 . 9 4 , <
~ .01. There were no
significant age differences in percent correct on the
vocabulary test, F( 1,79) = 2.49, p = .1 I.
Table 1. Means (and Standard Errors) of
Participant Characteristics
Younger
Older
Adults
Adults
(N = 40)
(N = 40)
Education*
2.85 (.07)
3.42
(.16)
Dig. Span Back.* 9.10 (.36)
6.10
(.27)
Digit-Symbol*
74.40 (2.36) 50.03 (1.71)
(.lo)
Reading Span*
3.31 (.12) 2.73
Vocabulary
79.43 (1.26) 83.31 (2.10)
Contrast Sens.*
37.87 (.45) 35.07 (.35)
*p < .05.
With respect to contrast sensitivity, there
were significant age differences, in that younger
adults correctly identified more letters on the PelliRobson Chart compared to older adults, F( 1,79) =
2 4 . 3 0 , ~< .01. See Table 1 for means and standard
errors.
Target word reading times were collected
using E-prime (2000). An analysis of variance was
performed to compare the effects of age (younger
adults and older adults), word predictability (high
and low), and contrast (high, medium, and low).
Target word reading time was the dependent
variable. Table 2 presents the means and standard
errors for target word reading times by condition.
The main effect of age was significant, F( 1,
78) = 2 8 . 5 3 , ~
< .01, q2= .27, as older adults spent
more time reading target words ( M o l d = 842 ms,
SEold = 33), relative to younger adults (MYounger 61 8 ms, SEYounger = 26). The main effect of
predictability was also significant, F( 1, 78) = 8.62,
p < .01, q2= .lo. High-predictability words were
read faster (MHigh = 704 ms, S E H i g h = 18) than lowpredictability words ( M L=~756,
~ S E L=~27).
~ In
addition, the main effect of contrast was significant,
F(2, 156) = 4 2 . 5 7 , ~< .01, $?=.35. Planned
comparisons showed that low-contrast words were
~ ms, S E L=~36)
~ than highread slower ( M L=~909
contrast words (MHigh = 636 ms, S E H i g h = 25), t(79)
=6.83,~
< .01, and medium-contrast words
(MMedium = 646 mS, SEMedium = 23), (79) = 6.74, p <
.O1. The reading times of high-contrast words and
medium-contrast words were not statistically
different, t(79) = .49,p = .62.
Table 2. Means (and Standard Errors) of Target
Word Reading Times in Milliseconds
Younger
Older
Adults
Adults
(N = 40)
(N = 40)
High Predictability
High Contrast
552 (3 1)
678 (40)
Medium Contrast 572 (38)
683 (32)
Low Contrast
711 (34)
1029 (47)
Low Predictability
High Contrast
540 (29)
773 (60)
Medium Contrast 569 (29)
759 (44)
762 (46)
1132 (85)
Low Contrast
The Age X Predictability interaction was
significant as well, F( 1,78) = 5.1 1,p < .05, q2=
.06. A comparison of means revealed that the
predictability effect was significant for older adults
(i.e., a significant difference between the amount of
time spent reading low-predictability words verses
high-predictability words), MOld-Low - MOld-High = 9 1
ms, t(39) = 2.94, p < .01. In contrast, the
predictability effect was not significant for younger
adults, MYounger-Low - MYounger-Hlgh = 11 mSy@9) =
.97,p = .48.
The Age X Contrast interaction was also
significant, F(2, 156) = 3.27, p < .05, q2= .08.
Mean comparisons showed that the difference
between the time spent reading low-contrast words
and high-contrast words was greater for older adults
(MO,d-Low- MOld-High = 355 ms), (39) = 5 . 0 3 , ~
< -01,
than for younger adults and (MYounger-Low - MYoungerHigh = 191 ms), t(39) = 3 . 8 7 , ~
< .01. Similarly, the
difference between the time spent reading lowcontrast words and medium-contrast words was
greater for older adults (MOld-Low - MOld-Medium = 360
ms), t(39) = 5.79, p < .01, than for younger adults
Downloaded from pro.sagepub.com at PENNSYLVANIA STATE UNIV on September 13, 2016
,
I
I
PROCEEDINGS of the HUMAN FACTORS AND ERGONOMICS SOCIETY 47th ANNUAL MEETING—2003
and (MYounger-Low - MYounger-Medium = 166 ms), t(39) =
3.88,~
> .01.
The Age X Predictability X Contrast
interaction was not significant, but the a priori
hypotheses were tested using planned comparisons.
These revealed that the predictability effect (i.e.,
longer reading times for low-predictability words
compared to high-predictability words) was not
significant in any of the contrast conditions for the
younger adults (MYounger-High Contrast-Low Predictability MYounger-High Contrast-High Predictability = - 12 ms; MYoungerMedium Contrast-Low Predictability
- MYounger-Medium Contrast-High
Predictability = -3 ms; MYounger-Low Contrast-Low Predictability
-
MYounger-Low Contrast-High Predictability = 5 1 mS).
However,
older adults demonstrated significant predictability
effects in the medium-contrast condition
Predictability - M H i g h Predictability = 76 mS) t(39) = 2.37, p
> .05, but not in the high-contrast condition ( M L ~ ~
Predictability - MHigh Predictability = 95 ms), t(39) = 1.63,p
= .11, or the low- contrast condition (MLo~
Predictability
- M H i g h Predictability = 103 ms), t(39) = 1.62,p = .I 1.
DISCUSSION
Past research has found that some agerelated text processing deficits can be minimized or
eliminated when some forms of text degradation are
used (Madden, 1988; Speranza, Daneman, &
Schneider, 2000). The results of these past studies
suggest that older adults may be able to compensate
for some forms of text degradation by relying on the
abundant experience they have had with language.
Older adults may, in fact, have more semantic and
pragmatic information available to them because
they have more linguistic experience than younger
adults do.
The goal of the present study was to explore
whether contrast reduction, which is commonly
encountered in everyday life, would have a similar
effect; that of cuing older adults to process the text
more deeply than they would if it were presented
intact. The results of this study suggest that older
adults do not compensate for all forms of text
degradation by relying more heavily on contextual
information. In the current study, older adults seem
to have relied on contextual information to facilitate
language processing in the medium-contrast
condition, but not in the high- and low-contrast
conditions. The fact that older adults did not have
245
significant effects of predictability in the highcontrast condition is not entirely surprising, in light
of past research that demonstrated that older adults
have encoding deficits, particularly in conditions
when they are not constrained to reads thoroughly
(e.g., Rabinowitz, Craik, & Ackerman, 1982). In
addition, it could be that in the low-contrast
condition older adults’ contrast sensitivity declines
prevented them from processing the sentence
context to the extent necessary to use that
information to facilitate processing the target word.
Hence, the degradation in the medium-contrast
condition may have been noticeable enough to cue
older adults to read more thoroughly, yet not so
extreme that it interfered with processing the
context of the sentence.
Another important finding from this study is
that in the low-contrast condition older adults were
slowed to a much greater extent, compared to
younger adults, and they were not able to
compensate using their extensive knowledge about
language as previous studies may have suggested.
Surprisingly, younger adults did not demonstrate
context effects in this study. Since younger
participants read the sentences quickly, it is possible
that the effects of word predictability extended
beyond the target word but at a reduced level.
Alternatively, young adults may have been able to
achieve the comprehension demands of the task
with only a superficial reading of the text.
The results of this study are particularly
relevant for text design. While most text design and
display research is based on reading performance of
young adults, the current study demonstrates the
differential effects certain text display
characteristics may have on a person depending on
their age. Specifically, reduced contrast slowed the
reading time of older adults much more then that of
young adults, even though the mean contrast level
in the low condition was lower for young adults. In
other words, young adults are significantly more
tolerant to contrast reduction.
More research is needed to further explore
the effects of text degradation, such as contrast
reduction, on younger and older adults’ reading
strategies. This research can provide information to
aid in developing guidelines for designing printed
materials and computer-presented text that facilitate
language processing for younger and older adults.
Downloaded from pro.sagepub.com at PENNSYLVANIA STATE UNIV on September 13, 2016
I
I
I
I
I
I
I
I
246
PROCEEDINGS of the HUMAN FACTORS AND ERGONOMICS SOCIETY 47th ANNUAL MEETING—2003
Text presentation guidelines are particularly
important at this time; as technology grows
information is increasingly being presented in new
formats, such as on electronic displays. Different
formats may have different perceptual qualities and
it is necessary to understand how the various
qualities affect the reading behavior of younger and
older adults, so as to make communication more
likely to be successful and efficient.
ACKNOWLEDGEMENTS
This research was supported in part by
grants from the National Institutes of Health
(National Institute on Aging) Grant RO 1 AG 18177
and Grant T32 AGO00175 and by Seed Grant PO1
AG172 1 1 from the Center for Research and
Education on Aging and Technology Enhancement
(CREATE).
REFERENCES
Charness, N., & Dijkstra, K. (1999). Age,
luminance, and print legibility in homes,
offices, and public places. Human Factors,
41(2), 173-193.
Craik, F. I. M., & Byrd, M. (1982). Aging and
cognitive deficits: The role of attentional
resources. In F. I. M. Craik & S. Trehub
(Eds.), Aging and cognitive processes (pp.
191-211). New York: Plenum.
Daneman, M., & Carpenter, P. A. (1980). Individual
differences in working memory and reading.
Journal of Verbal Learning and Verbal
Ability, 19,450-466.
E-Prime 1.O [Computer software]. (2000).
Pittsburgh, PA: Psychology Software Tools.
Hartley, J. T. (1993). Aging andprose memory:
Tests of the resource-deficit hypothesis.
Psychology and Aging, 8(4), 538-551.
Kemper, S., & Kemtes, K. (2000). Aging and
message production and comprehension. In
D. C. Park (Ed.), Cognitive aging: Aprimer
(pp. 197-213). Philadelphia, PA, US:
Psychology Press/Taylor & Francis.
Madden, D. J. (1988). Adult age differences in the
effects of sentence context and stimulus
degradation during visual word recognition.
Psychology and Aging, 3(2), 167-172.
Mitzner, T. L. (2002). Effects of reduced contrast
on young and older adults’ utilization of
context during reading. Proceedings of the
Human Factors and Ergonomics Society
45th Annual Meeting.
Pelli, D. G., Robson, J. G., and Wilkins, A. J.
(1988). The design of a new letter chart for
measuring contrast sensitivity. Clinical
Vision Sciences 2, 187-199.
Rabinowitz, J. C., Craik, F. I., & Ackerman, B. P.
(1982). A processing resource account of
age differences in recall. Canadian Journal
of psycho lo^, 36(2), 325-344.
Rayner, K., & Well, A. D. (1996). Effects of
contextual constraint on eye movements in
reading: A further examination.
Psychonomic Bulletin and Review, 3, 504509.
Schwanenflugel, P. J. (1986). Completion norms for
final words of sentences using a multiple
production measure. Behavior Research
Methods, Instruments and Computers,
18(4), 363-371.
Shipley, W. C. (1986). Shipley Institute of Living
Scale. Los Angeles: Western Psychological
Services.
Speranza, F., Daneman, M., & Schneider, B. A.
(2000). How aging affects the reading of
words in noisy backgrounds. Psychology
and Aging, I5(2), 253-258.
Wechsler, D. (1 997). Wechsler Adult Intelligence
Scale III. (3rd Ed.). San Antonio, TX: The
Psychological Corporation.
Wingfield, A., & Stine Morrow, E. A. L. (2000).
Language and speech. In F. I. M. Craik
(Ed.), The handbook of aging and cognition
(pp. 359-416). Mahwah, NJ, US: Lawrence
Erlbaum Associates Inc Publishers.
Downloaded from pro.sagepub.com at PENNSYLVANIA STATE UNIV on September 13, 2016