Aging and Sensory Perception: Changes in Sensory Thresholds

What are sensory thresholds? How does sensory perception change with age? This lesson will answer these questions and teach you even more about sensory changes in late adulthood.

Changing Sensory Perceptions

Bob remembers taking Sunday drives through the country when he was a young man. The smell of the newly cut hay in the air was irresistible. Sometimes, he would stop to put out a blanket and enjoy the warm sun on his skin. This is one of his most enjoyable memories.

Recently, Bob was feeling a bit nostalgic, and he took a similar Sunday drive. Bob saw some farmers cutting hay, but he couldn’t smell the hay. Also, the sunlight didn’t seem to warm him as he remembered. Bob did not enjoy the drive the way that he did when he was younger. Bob wonders what has changed. Why isn’t the experience the way that he remembers it? Why couldn’t he smell the newly cut hay? Why didn’t the sunlight feel warm on his skin?

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The answer to Bob’s question is that the sensory environment hasn’t changed, but Bob has! He has found out that sensory perception changes as we grow into late adulthood. These changes can affect his enjoyment of an activity, like it did in the example of the Sunday drive. Sensory changes that occur with aging can also affect appetite, social involvement and ability to perform tasks.

Sensory Thresholds

Changes in sensory thresholds are one reason for this age-related change in sensory perception. A sensory threshold is the level of strength a stimulus must reach to be perceived. Let’s discuss two types of sensory thresholds: absolute thresholds and differential thresholds. The lowest level of strength necessary for sensory detection is called an absolute threshold. An example of an absolute threshold would be the exact point that a sound becomes just loud enough to be noticed.

The differential threshold is the smallest amount of change necessary to determine a stimulus has become stronger. This is also known as the ‘just noticeable difference.’ For example, imagine you are holding identical weights in each hand while wearing a blindfold. If I were to gradually add a very small amount of weight to one hand, you would reach the differential threshold at the exact point where you were able to notice that one side is heavier than the other.

In order to understand changes in sensory perception that occur with age, it’s important that we understand these sensory thresholds. This is because as we get older, these sensory thresholds change, and our perceptions of the surrounding environment changes with them. Changes to Bob’s sensory thresholds are what caused him to have a different sensory experience when he went on a Sunday drive as a young man, compared to when he went on a Sunday drive as an old man.

This made the smell of the newly cut hay and warmth of the sunlight less noticeable to Bob when he was older. Typically, aging will increase sensory thresholds. This, in turn, decreases our sensory awareness, which means that the amount of stimulation needed for sensory awareness must increase.

Common Sensory Changes with Age

Now that we understand sensory thresholds and their effect on our sensory perception, let’s look at some common sensory changes that occur as we reach late adulthood.

Hearing

As we age, our ability to detect sounds typically decreases in both ears. This is especially true of high-frequency sounds. It may also become difficult to understand speech when there’s background noise or to differentiate between certain sounds. Presbycusis is the term used for age-related hearing loss that gradually occurs as people get older. This hearing loss can be managed in different ways. The most common way is the use of a hearing aid.

Vision

As we age, our vision changes as well. Visual acuity, or sharpness of vision, typically declines. The visual field, or area in which objects can be seen, becomes smaller. Reduced peripheral vision is also a concern. Presbyopia, or difficulty focusing the eyes on close objects, is the most common visual problem associated with aging. This can usually be corrected with glasses or contact lenses.

Touch

As we age, our sense of touch may become less sensitive or the sensations may change. This is important because the sense of touch also includes being aware of pain, temperature and body position. An older person may have a reduced sensitivity to pain. This may sound great, but it can be a problem. Imagine not realizing that an injury is severe because the pain does not significantly bother you.

Decreased temperature sensitivity may also occur with age. If it becomes difficult to tell the difference between cool and cold or warm and hot, an increased risk of injury can occur. The ability to perceive where your body is in relation to the floor is another concern that can occur with aging. This may cause difficulty walking and increases the risk of injury from falling.

Taste

As we age, the number of taste buds that we have in our mouth decreases, and the taste buds that are left become less sensitive. Sweet and salty tastes are the first to go, followed by bitter and sour. This increased sensory threshold for taste can cause loss of appetite in older people. If a person no longer enjoys eating as they get older, they may not eat enough or may not eat enough healthy foods. This could result in malnutrition.

Smell

As we age, our sense of smell begins to diminish as well. This may be due to a loss of nerve endings and a decreased amount of mucus being produced in the nose. This diminished sense of smell can also have a negative impact on appetite because of its close relation to the sense of taste. It can also be dangerous because we rely on our sense of smell to warn us of hazards in the environment. A simple example of this would be the danger of not smelling the smoke from a fire that is just starting.

Lesson Summary

Changes in sensory thresholds are one reason for age-related changes in our sensory experiences. A sensory threshold is the level of strength a stimulus must reach to be perceived.

Two types of sensory thresholds are absolute thresholds and differential thresholds. The absolute threshold is the lowest level of strength necessary for sensory detection. The differential threshold is the smallest amount of change necessary to determine a stimulus has become stronger.

As we get older, sensory thresholds change, and our perception of the surrounding environment changes with them. Sensory thresholds typically increase with aging. This means that the amount of stimulation needed for sensory awareness must increase as well. Remember Bob? The changes that he experienced in sensory perception with age are one example of the difference a change in sensory thresholds can make.

A decreased sensitivity to taste and smell can cause a loss of appetite, which could result in malnutrition. Decreased smell could also impede the ability to detect a danger. A less sensitive sense of touch can result in reduced sensitivity to pain, decreased temperature sensitivity and difficulty perceiving where your body is in relation to the floor. Vision and hearing difficulties that result from changes in sensory perception can also be problematic. However, these difficulties can usually be managed with glasses, contact lenses or a hearing aid.

Learning Outcomes

Once you’ve completed this lesson, you’ll be able to:

  • Define sensory threshold
  • Differentiate between absolute and differential thresholds
  • Explain why our sensory perception decreases with age
  • Provide some examples of sensory changes with age
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