> Dynamics of Population Aging

POPULATION AGING is normally determined by (1) by birth (fertility) rates and (2) death (mortality) rates—high birth rates result in lower proportions of older people, low birth rates result in higher proportions of older people.

As a society moves from a condition of high rates of birth and death, to one of low rates of birth and death, the overall population begins to age. Demographers use the term "demographic transition" to refer to this transition process.

And it's happening now throughout the world. In the United States the oldest baby boomers are almost sixty-five years old and about to retire—the youngest are about forty five. As this group reaches age sixty five starting in 2011, the present population of older people will begin to explode:

• By 2030, America's elderly population is expected to reach 72 million, more than double the number in 2000.

• By 2030, 55 countries are expected to see their 65 and older populations grow to at least 20 percent of their present total.

• By 2050, Europe will continue to be the world's oldest region with its elder population increasing more than five fold, from 40 million to 219 million.

Such immenent changes in life expectation is a unique phenomen, never before occuring throughout human history. Clearly, enormous social and economic changes in the world's societies lie ahead.

> Biological / Physiological Changes

BIOLOGICAL AGE does not correlate with chronological age. While most of us recognize advanced age in people when we see it, appearances alone do not determine how old we really are. Something more is needed.

Unfortunately, no relable measurement exists that allows us to to determine the biological age of humans and most other animals. The most promising, however, are in the realm of genetic and cellular functioning. Two biological phenomena appear related to the aging process:

• Accumulation of waste products in the cells
• Loss of elasticity of the connective body tissue

These changes, sometimes called nongenetic, occur at the cellular level. They have a direct bearing upon many declines we experience in our physical and sensory capabilities.

These changes effect the level of functioning of the cells and correlate with increased chronological age, but a direct cause-and-effect relationship has not been determined.

Accumulation of  Waste Products

AS CHRONOLOGICAL AGE INCREASES, cells function less efficiently. This inefficiency results in a build-up of waste products from the metabolic processes.

Most frequently, this is an accumulation of lipofuscin, an insoluable fatty substance which, when it exists in large quantities, is known to affect cellular functioning.

It is this build-up wich causes the familiar age spots, but it is also know to occur in the outer cortex of the brain, in nerve cells, in the heart muscle, and in many other tissues which monitor vital body functions.The overall affect is highly debatable, and the phenomenon is undergoing scientific study.  

Loss of Elasticity in Connective Tissue

THE CULPRIT IS COLLAGEN, a substance which constitutes more than one-fourth of the body's protein. As age increases, the connective tissue becomes less elastic.

The most obvious evidence of changes in collagen is wrinkles. However, since collagen fibers also surround the cells and blood vessels of the body, stiffening of these fibers could also affect the efficient functioning of many body systems.

Senescence

MANY BODILY CHANGES take place over the entire lifespan— some beginning with birth. They are  part of a relentless, post-maturational phenomenon called senescence (biological aging).

Senescence results in a decrease in the physical capacity of an individual, accompanied by an increase in a person's vulnerability. As a result, any product or environment may become less friendly and less supportive for some people while adequately providing support for others.

Most of the changes that characterize senescence occur slowly. As thay occur, individuals adapt to them. For example, people with arthritis may select utensils with larger and softer handles to ease the pain and enhance their grip.

Designers and architects have a profound influence on products and environments. A transgenerational mindset helps them ensure that their designs accommodate people of all ages and abilities.

Adaptation

THE ABILITY OF HUMAN BEINGS to adapt to change is one of the most  positive spects of the aging process. It transcends all areas of human functioning, from living independently, despite overwhelming physical problems, to being able to compete with younger employees in the work force.

Changes and adaptation foster diversity, and our older population is no exception. While generalizations about older people are dangerous, the following observations reveal how much like us, they really are:

• Older people are extremely sensitive to the fact that their personal resoources are diminishing.

• They resent condescension in all of its forms and do not want to be patronized.

• They want to remain independent as long as possible.

• Most of all, they want to retain their dignity and self respect.

Accommmodating "transgenerational" products and environments provide a built-in range of adaptation that allow users—of any age or ability—to adjust them  to their individual needs and preference.

> Psychological Changes

The aging process brings change. During our lifetime, many individual changes we undergo are psychological. Three particularly relevant areas of psychological change are: information processing, personality, and the myth of senility.

Reaction Time

Reaction time increases with age. Reasons for this are difficult to isolate. The increases could be caused by a slowing of perception, transmission to the brain, decoding and recoding in the brain, transmission to the appropriate responding mechanism, an/or the mecanism of the response itself.

When time is a factor, age differences appear. This change might affect products in which rapid responses are required in order to accomplish a task (e.g., using an electric food processor). Most older persons need a longer period of time to react.

Reaction time is also correlated with the complexity of the task (e.g., operating a pushbutton door lock). If both age and complexity increase, then behavior becomes less efficient.

Since so many of today's routine activities are both complex and require rapid resposes, these factors may make the tasks harder for older people. If physical and/or health problems are not present, adaptation and practice offset age-related decrements.

Experience and usage can negate some reaction time loss. For example, on an assembly line, most older workers are able to keep production quotas because they are constantly utilizing skills, experiences, and behaviors which have been developed over the years.

Intelligence

Intelligence does not appear to change with age until quite late in the life span. Decrements that do appear seem to be more a factor of motivation, vocabulary, contemmpary skills, and speed than they are a factor of age-related losss. For example, old people may not be as highly motivated as younger people when taking tests,

Older groups are usually at a disadvantage with younger groups when level of formal education and recency of contact with a testing environment are considered.

In general, speed decreases as age increases, and since most intelligence test are timed, this could affect overall scores. The vocabulary of older people is frequently limited and less contemporary than that of younger persons.

This is not due to lack  of intelligence, but rather to two educational differences—fewer years of formal education and fewer recent classroom experiences, which would expose tthe person to a situation that would build a more cntemporary vocabulary.

Designers need to take this vocabularly issue into account when designing complex tasks such as setting the timing sequence on appliances.

Learning

Learning appears to be unaffected by age. It may take longer for an older person to learn something, but this illustrates, once again, that speed rather than ability differentiates older from younger learners.

Designers should note that for older people, retention is greatest for things which are both seen and heard (redundant cuing). Retention is next greatest for things which are heard, and lowest for things which are seen.

Designers may help older people by breaking complex tasks into simpe, sequential sub-tasks, thus making learning easier.

Memory

Memory changes that accompany the aging process have a definite pattern. As people age, they tend to have more and more difficulty with short-term recall whereas long-term recall remains much more inact.

Reasons for this are unclear. It may be due to accumulated loss of neurons in the brain, but this is currently subject to debate.

Some researchers believe that social factors are responsible, since the past, for many persons, may have been much more pleasant than the present. However, there is no general agreement in this matter either.

The programming of task sequences, such as found in pre-dialing features on many telephones, begins to address the problem of short-term recall.

Problem-Solving

Problem-solving techniques differ as age increases. Older people are much more reluctant to use trial-and-error beaviors than are younger people.

Prior to attempting a solution, most older people prefer to take time to "think through" the situation. Younger people are prone to use trial and error more quicky and more frequently.

This behvior could affect the manner in which older Americans use mechanical devices. Clear, easy-to-follow directions would go a long way to encourage trial and error behavior and avoid intimidation in older people.

Personality appears to remain fairly constant over the lilfespan. Some say that in old age we become more and more like the person we were in our youth.

The placid youngster becomes a more placid older person, and so on. This is generally true, but wide variations have also been observed, and it is difficult to make predictions in this area.

Given the diversity among the older population, designers should consider the relationship  between personality and product selection, question their own assumptions about older people, and avoid designing products based on stereotypes.

Everyone assumes that, when you get old, it is "natural" to become forgetful and to lose contact with reality. This simply is not  true.

Only a small percentage (4-5%) of older people experience physical and/or psychological decrements warranting institutionalization.Ninety-four percent of the older population remain independent.

The myth of senility obsures this fact. Designers need to examine their own attitudes in order to avoid minconstruing normal changes in the aging process as mental health problems.