designing appliances for older persons-老年人(2)

老年人设计

abilities provides opportunity to prolong functional independence.

2.Cognitive capacities related to age

Age-related deficiencies in cognitive abilities may affect older adults operating semi-familiar or unfa-miliar appliances. For example, a person may strug-gle to use a DVD player in a hotel, when confronted with a remote control that has customary control but-tons but an unfamiliar layout. The limited capacity of working memory may constrain the number of per-spectives or action sequences that the person may consider [22]. D eclines in attention and cognition associated with ageing may restrict capacity. MCI and more severe forms of cognitive impairment (e.g., Alzheimer’s disease and Parkinson’s disease) may further weaken cognitive abilities, which may vary considerably on a daily basis.

Different cognitive abilities deteriorate at different rates [7]. Inductive reasoning, spatial orientation, verbal memory and perceptual speed, all monotoni-cally decrease to old age from around mid-20s to early 30s [27]. Numeric and verbal abilities both maximize in the mid-40s and then they decrease until the 60s, at which they plateau.

For appliances used by seniors, designers’ atten-tion to the variations in the rates of deterioration in cognitive abilities may be pivotal. The use of mul-tisensory cues in appliances may ameliorate inevita-ble decline in sensory function. Laurienti et al. found that response times of older listeners provided with redundant visual and auditory cues were equal to those of a young population given only visual cues [12]. They see a practical application of their findings is the use of videophones to aid listener comprehen-sion by affording redundant visual and auditory cues. This stance accords with our conviction to espouse multisensory training strategies to counter age-related functional decline.

3.Human-appliance interaction

The creation of new appliance technologies that compensate for declining abilities requires the inte-gration of behavioral science and engineering. Stan-dard texts on human factors engineering, such as Wickens et al. discuss human-machine systems in terms of human-information processing [34].

The cognitive aspects of interaction between a human and an appliance can efficaciously be repre-sented by the model of human information process-ing in Figure 1. Through their senses, users perceive meaning from the signals from the appliance or the broader environment. The perceptual process de-pends on sensual input, attention and long-term

memory.

Figure 1. Model of Human Information Processing [31]

3.1.Senses, perception and attention

Interaction with appliances is a two-way process in which users send signals to the technology with input devices, commonly called controls, and receive in-formation displayed to them by the technology through their visual, auditory and tactile senses. In-formation processing is affected by the communica-tion medium: the motor ability of humans in manipu-lating controls and the performance of visual, audi-tory and tactile senses in receiving signals from dis-plays. Issues arise regarding the ability of users to signal using the controls (e.g., dexterity in manipulat-ing a control) and in their ability to perceive signals from the technology. Extraction of meaning from the signals received is the process of perception, in which the attribution of meaning derives from ex-perience formed over time. Perception depends on attention and associations drawn from memory. The process of perception concerns bottom-up processing of signals (an ability to resolve the signals relating to factors such as contrast sensitivity and visual acuity) and top-down processing from the users experience, depending on cognitive processes relating to memory and attention.

3.2.Memory and attention

Proficiency in using an appliance depends on ca-pacities and capabilities of working and long-term memory and attention resources. The strength of these lessens with age, appreciably because of neuro-logical deterioration.

The working memory of operators affects their ap-titude in using functionally complex technological

P.G. Higgins and A. Glasgow / Development of Guidelines for Designing Appliances for Older Persons 334