Sensory Origin for Stroop effects.
Professor Bruce A. Schneider
Dr. Boaz M. Ben-David
The Stroop test is widely used as a test of selective attention. In the past 40 years this test has shown that selective attention is deteriorating with age. In other words, it is harder to focus our attention and ignore distracting information as we age. In this test we ask participants to name the font color of printed words. In some cases it becomes "tricky", for example when you have to name the font color of the word RED printed in a blue font. In other words, people find it difficult to say "blue" when they see the word RED. This condition is called an "incongruent" Stroop task. Usually, researchers find that it takes older adults longer to complete the "incongruent" task, than the time it takes younger adults to complete the same task. This finding led researchers to the conclusion that older adults have a deteriorated ability for selective attention. In this study, we are asking whether these differences arise from visual degradation with age and not from cognitive age-differences. In other words, maybe this test is not comparing attention differences between older and younger adults, but actually it is testing differences in vision.
In the present study, 88 younger adults performed a Stroop test with two color-sets, a standard color-set and a desaturated color-set, to simulate an age-related decrease in color perception. This color manipulation with younger adults was sufficient to lead to an increase in Stroop effects that mimics age-effects. We conclude that age-related changes in color perception can contribute to the differences in Stroop effects observed in aging. Finally, we suggest that the clinical applications of Stroop take this factor into account.
Aging and Workload Capacity: Do older adults integrate visual stimuli differently than younger adults?
Boaz M. Ben-David, Ami Eidels & Lulu Li
Centre for Research on Biological Communication Systems, University of Toronto, Mississauga
Department of Psychological and Brain Sciences, Indiana University
Consider the following situation: Mrs. Jones, an elderly pedestrian, is about to cross the road on a dark night. She looks to the left to spot an oncoming vehicle. A single signal (e.g., the front light of the vehicle) is sufficient to stop her from crossing. Two signals (e.g., two lights) constitute redundant superfluous information. However, there is a bulk of evidence to suggest a gain reaped in detection from the presence of multiple targets -- the Redundant Targets Effect (RTE). This speed up may be the result of mere statistical facilitation, or of an interaction in the processing of the two signals. How will the performance of the elderly person compare with that of her 20-year-old grandson, young Mr. Jones? It is reasonable to assume that he will make his decision faster than she will. An age-related slowdown of responses is a common result in many cognitive tasks. But, will the elderly person integrate the visual signals differently than her younger counterpart? In this study, for the first time, we compare the processing of visual redundant information between younger and older adults.
Our results show that Elderly Mrs. Johns will make her decision to cross the street more slowly than her grandson. However, she may integrate redundant visual signals as efficiently as her grandson. A busy intersection, entailing distractors in a complex visual scene, will slow down both of them, but the effect of unwanted distractors would be more salient for Mrs. Jones.
Back to Vision Studies
Effects of Aging and Noise on Real-Time Spoken Word Recognition:
Evidence from Eye Movements
Boaz M. Ben-David, Craig G. Chambers, Meredyth Daneman, M. Kathleen Pichora-Fuller, Eyal M. Reingold, Bruce A. Schneider
As people age, they experience greater difficulty understanding speech, particularly in environments with background noise. For example, although a 70-year-old grandmother can enjoy her favorite talk radio program at a normal volume in a quiet room, she may have to substantially increase the volume when her grandchildren are playing in an adjacent room, and even then may not accurately hear all of the dialogue. A central question in lifespan approaches to human communication concerns the origin of these speech comprehension difficulties, whether they stem from age-related sensory decline and/or cognitive changes. Most studies of age-related declines tend to use traditional accuracy-based tests of speech comprehension, e.g., participants are asked to repeat spoken words or sentences presented in different listening conditions. However, research in the field of spoken word recognition has shown that the mapping of speech sounds to lexical candidates begins immediately on the basis of the initial sounds in an unfolding word. In this study, Twenty-four younger and 24 older adults followed spoken instructions referring to depicted objects, e.g., "Look at the candle". Eye movements captured listeners' ability to differentiate the target noun ("candle") from a phonologically similar alternative (e.g., "candy" or "sandal"). Manipulations included the presence/absence of noise, the type of phonological overlap in target-alternative pairs, and the number of syllables. In the study we controlled for age-related differences in word recognition accuracy, by tailoring noise levels. In other words, we have presented more noise to younger adults than to older adults. We found similar on-line processing profiles for younger and older adults when targets were discriminated from alternatives sharing onset sounds (e.g., candle and candy). We conclude that real-time spoken word recognition processes appear similar for younger and older adults (in most cases), after we can control for differences in hearing thresholds.
Back to Vision Studies