Older adults’ perception abilities through visual system, auditory system, somatosensory system, gustatory system, and olfactory system generally decline with advancing age. Boot, Nichols, Rogers and Fisk (2012) provided a comprehensive overview of age-related decline in vision, audition, and haptics. This section mainly presents updates of these perceptual changes and adds new topics such as dynamic visual acuity, spatial acuity, and olfactory function.
Due to changes in the structure of the eyes and visual processing system, older adults’ visual abilities decline, which would affect lots of interactions in their daily life.
Dark adaption, illumination, glare.
As people age, their ability to quickly adapt dark environment decreases, and they need more illumination to see objects clearly. In addition, they are more sensitive to glare than younger adults. The changes of these abilities strongly influence their daily lives, especially driving activity and use of computer. Generally, increasing illumination can help the elderly to perceive information. However, glare would occur when illumination is greater than the light that eyes are currently accustomed to.
The effect of glare can be avoided by reducing the intensity of light sources (such as, sunlight or high-powered lamps) and the number of surfaces that produce highly reflective light to reduce the effect of indirect glare which was produced from bright surface ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”bWSjFA4j”,”properties”:{“formattedCitation”:”(Sharit & Czaja, 2012)”,”plainCitation”:”(Sharit & Czaja, 2012)”,”noteIndex”:0},”citationItems”:[{“id”:1312,”uris”:[“http://zotero.org/users/local/1q3J2qM4/items/9H44BGW2″],”uri”:[“http://zotero.org/users/local/1q3J2qM4/items/9H44BGW2″],”itemData”:{“id”:1312,”type”:”book”,”abstract”:”There have been many changes in work, including the rapid infusion of technology into work processes, a reduced emphasis on effortful manual labor, an increased emphasis on the service sector, changes in systems of work organization, and the proliferation of alternative work arrangements, as well as new perspectives on aging processes.
These changes argue for a reappraisal of issues related to job design for older workers.
In this chapter, in addition to a focus on topics detailing how to ensure that the demands of the job are commensurate with the cognitive, sensory, and motor capabilities of older workers and their health conditions, a broader perspective to instituting job design strategies is presented. In this regard, topics on training older adults, job motivation and its relationship to job design, as well as the emergence of mentoring roles for older workers and the prospects for older workers collaborating on teams are also discussed.”
Visual acuity: visual acuity is the ability to distinguish detail of objects and is often used to measure visual ability.
Age-related eye diseases such as ARMD, cataracts and glaucoma affect visual acuity of older adults. The eye diseases (such as age-related macular degeneration (ARMD), cataracts and glaucoma) occur as people age and affect their visual acuity.
Generally, increasing the size, lightness and contrast of objects can compensate for the loss of visual acuity. In addition, top-down processing, clarity of stimulus (such as consistent spacing) and providing other Supplementary information (such as background color) can help older adult perceive information
DVA is defined as the ability to discriminate details of an object when relative movement exists between object and observer, which is important to perceive motion information such as in driving, video games or in scrolling (information is moving in displays) and judge the future location of a moving stimulus. However, the ability declines as age, and the loss of retinal sensitivity is major cause of deterioration in older adults (Quevedo et al., 2018). Research has shown that DVA can be modulated by exposure time, contrast
between object and background and illumination (Stevens & Cain, 1987). Since the DVA decreases as the speed increases, reducing the speed of playing in automatic displays (such as text reader or bulletin) is one way to ensure older adults perceive information. In addition, increasing object’s size, illumination and the contrast of item can improve performance of perceiving information in older adults.
Regarding vision, the adjustment ability is the ability of the eye to adjust the focal length freely and dynamically to clearly observe objects at different distances. The strength of this adjustment is determined by the amplitude of accommodation in the ciliary muscle determines. The measurement of over 4200 eyes showed the curves of gradually decline, with the mean value of monocular accommodation is around 11 at the age of 20, which decreases to around 6 at the age of 40, around 2 at the age of 50, and only 1 at the age of 70 (Duane,1922). Thus, it is important to avoid displays are placed at different distances in a task.
With age, the ability to discriminate and perceive shorter wavelength light decreases. Three cones on the retina are responsible for distinguishing colors. As the lens of eyes becoming yellowish, older adults are less sensitive to the colors at the blue end of spectrum (Said and Weale, 1959), whereas the reception in red and yellow areas remains relatively stable(Cooper et al., 1991). Color vision deteriorate significantly after people age 70, especially the ability to discriminate yellow-blue (distinguishing blue from purple and yellow from green and yellow-green) color. Color-vision deterioration were uncommon in people younger than 70. However, data showed that about 45% of people in the mid-70s, up to 50% of 85 and nearly two-thirds of older adults in their mid-90s have deterioration in color vision (Schneck et al., 2014).
Therefore, color code should avoid shorter wavelengths or only using blue or green, particularly at low saturation levels and low illumination.
Contrast sensitivity is the ability to detect grayness and background or distinguish between similar shades of light and dark (Beckley, 2016). A decrease in the contrast sensitivity function may affect the ability to: walk down steps, recognize faces, drive at night or in the rain, find a telephone number in a directory, read instructions. Older adults has lower contrast sensitivity than younger adults (Owsley, 2011). There is a debate that whether it is due to the neural system or optical factors (Burton et al. 1993).
Researches have shown that spatial frequency and luminance affected contrast sensitivity. Spatial frequency is defined as the number of cycles of grating per degree of visual angle(Thompson, 1985). High spatial frequencies correspond to features such as sharp edges and fine details, whereas low spatial frequencies correspond to features such as global shape. Older people’s contrast sensitivity declined at intermediate and high spatial (4-8c/deg and above), but no decrease at the lowest spatial frequency (1c/deg) (Elliott et al., 1990). As the luminance increased, contrast sensitivity improved, and the decline of contrast sensitivity would accentuated at low luminance (Burton et at, 1993). In addition, at lower spatial frequencies, increases in luminance would not improve the contrast sensitivity (Sloane et al., 1988). Therefore, considering the effect of brightness on contrast sensitivity for older adults, we can improve their contrast sensitivity by improving the lighting condition.
Haptic control, proprioceptive perception, temperature perception, vibration perception
Hearing impairment occurs in 60% of people aged 70 or older (Yamasoba, et al., 2013). The amplitude of 25dB or the frequency of 3 kHz are important criteria to evaluate hearing impairment and speech perception (Kryter, 1973; WHO, 2020). After the age of 40, the prevalence of hearing loss approximately doubles every ten years (Lin, Niparko, & Ferrucci, 2011). A 15-year study of 813 adult males indicated that the rate of change at the lower frequencies (0.5, 1, 2, 3kHz) is approximately four times greater after age 50 than before (1.2-1.4 vs 0.3-0.4 dB/year), while the rate of change for the highest frequency tested increases in a linear fashion over the entire adult age span (Brant, & Fozard, 1990).
Conductive hearing loss occurs when there is any blockage in the passage from the outer ear to the middle ear. Sensorineural hearing loss occurs when the cochlea is affected by aging or disease. As people age, their ability to detect faint sounds decreases. This can affect the quality of the sound heard, resulting in an inability to understand sounds and distinguish between sounds (Moore, 2003).
Auditory acuity and auditory localization. Older adults have difficulty in hearing auditory stimuli and localizing sounds. Age-related changes in hearing thresholds occur significantly earlier in the extended high frequencies, i.e., >8 kHz. For individuals aged 65–81 years old there was a decline of 0.7 dB per year at 0.25 kHz, 1.2 dB per year at 8 kHz, and 1.23 dB per year at 12 kHz (Lee et al., 2005). Given that unvoiced consonants are usually at high frequency ranging from 2kHz to 8kHz while vowels at low frequency (Ecophon, 2020), simply increasing sound volume would not help compensate the hearing loss.
In addition, men and women show different hearing loss at different frequency. Men have higher rate of bilateral hearing loss (approximately 2 times) in frequencies between 0.5–8 kHz. the rate of decline in hearing thresholds is much higher in men than women across 4–8 kHz frequencies, especially after the age of 50 years. In contrary, hearing thresholds at 6 to 12 kHz frequencies decline at a significantly faster rate in women than men. Besides auditory acuity, high frequency also affects sound localization in older adults.Therefore, high-frequency sounds should be avoided in any systems or products. As the thresholds for hearing acuity increases in older adults, it is good to provide overall volume control for them.
Older people are more affected by noise than younger people, which can affect them hearing and speech in unfavorable conditions. The deterioration in perceiving speech in noise may count to peripheral hearing, central auditory processing deficits and cognitive decline (Jayakody et al., 2018). There are some ways to help hear sounds in noise background such as using unique sounds which is distinct from background sound to ensure speech is not obscured by background sounds, providing other cues ( such as visual cues) with voice or installing noise abatement equipment.
“There have been many changes in work, including the rapid infusion of technology into work processes, a reduced emphasis on effortful manual labor, an increased emphasis on the service sector, changes in systems of work organization, and the proliferation of alternative work arrangements, as well as new perspectives on aging processes. These changes argue for a reappraisal of issues related to job design for older workers. In this chapter, in addition to a focus on topics detailing how to ensure that the demands of the job are commensurate with the cognitive, sensory, and motor capabilities of older workers and their health conditions, a broader perspective to instituting job design strategies is presented. In this regard, topics on training older adults, job motivation and its relationship to job design, as well as the emergence of mentoring roles for older workers and the prospects for older workers collaborating on teams are also discussed.
Haptics is the sense of “active touch” it combines two sources of sensory information: touch (tactile input on the skin) and proprioception (the sense of the position of body and body parts in space and relative to each other. Somatosensory system at the level of peripheral receptors and centrally affects the tactile abilities. The loss of touch sensory can impact on various aspects of function in older adults, including articulation of speech, hand grip, and postural stability (Wickremaratchi et al.,2006).
Sensitivity to vibration declines with age, and which is related to frequency, contact area, duration of stimulation. Although the loss of sensitivity decrease at both high and low frequency, it is more pronounced at high frequency in the elderly(Tremblay & Master, 2015).
Pressure perception. It’s the ability of sensing pressure. Older adults are less sensitive to pressure than younger adults, and the change become more pronounced as they age. However, there is variability among older adults in pressure sensitivity. Despite most seniors exhibited higher detection thresholds after 60 years, a substantial proportion (40%) still retain a sensitivity comparable to younger groups (Tremblay & Master, 2015).
Human skin has an ability to distinguish spatial details, especially the fingertips. However, this ability declines significantly with age, which is common on the body surface, but is more pronounced in the distal extremities (such as tiptoes). Thus, tasks that require discriminating spatial detail can be difficult for older adults.
Olfactory function declines with age, which involves older adults have higher odor thresholds, poor odor magnitude matching and odor identification than younger adults (Stevens & Cain, 1987). The rate of olfaction impairment in older adults is very high. Researches showed that about half population between 65 and 80 years had impaired olfaction, and more than three-quarters of people aged over 80 had such loss(Duffy et al., 1995) (Murphy, 2002). Olfactory ability has significant impacts on daily life (e.g. safety, nutrition, appetite) and emotion of people. Odors are sometimes used as an alert or indicator, such as leaks of gas, smoke.
However, older adults may not perceive these stimuli. The reasons that why the sense of smell deteriorates as age may be: (1) changes in the olfactory neuroepithelium, where the olfactory receptors cells decreases and alters, The epithelium thins and olfactory is replaced by respiratory epithelia; (2) changes in olfactory bulb and its laminae; (3) changes in brain regions involved in olfactory processing (Attems et al., 2015) (Lafreniere & Mann, 2009). Deficits in olfactory ability in the elderly indicate the importance of increasing concentration of odors and providing other cues to amplify the signal or indicator when it comes to odor related tasks and activities.
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