Sensory Threshold

Sensory Threshold in Psychology

As you may already know, we have five primary senses: smell, taste, sight, hearing, and touch. While these are the most observable senses, they are not the only senses we have. We have others, such as pain and body position and movement.

Our world is full of stimulus energy information (i.e. frequency, hertz, etc.), and our senses can detect much of it. Some animals have senses that can detect types of stimuli that we cannot. For example, dolphins hunt their prey by using sonar, a signal that judges distance based on how it bounces off surpasses. While we can detect a lot of energy information, we still require a certain amount of that energy to detect it consciously.

The sensory threshold can vary for everyone and often relies heavily on our past experiences, beliefs, expectations, and values.

Or, consider you are expecting an important call but are at a loud party. What affects your ability to detect the faint sound of your phone amid background noise? In psychology, signal detection theory is often used to describe this phenomenon.

Again, several factors can affect our ability to detect stimuli in these circumstances. Signal detection theory is often used to explain why a mother may be able to sleep through a loud alarm but quickly awakens to the faintest cry of her baby.

High Sensory Threshold

Once again, everyone's sensory threshold is different. Some of us will have a high sensory threshold, while others may have a low one. Sensory processing disorder is when an individual is on either extreme.

The effects of a high sensory threshold can easily be seen among children. Children with a high sensory threshold have a higher absolute threshold and therefore need more stimuli to react. These children might not respond to whispering and need to be spoken to at a louder volume to react.

Children with a high sensory threshold will often engage in sensation seeking. In other words, they actively look for sensory experiences because they need more stimulation to react. These children may be seen chewing on their shirts, fiddling and touching everything around them, or constantly moving.

Fig. 1, a low sensory threshold is characterised by high sensitivity, Freepik.com

In contrast, children with a low sensory threshold are extremely sensitive to stimuli. Their absolute threshold is much lower and does not require as much stimuli energy to react to it. These children might engage in behaviors that block stimuli, such as closing their eyes or plugging their ears. They also try to avoid sensory experiences that may overwhelm them and might be unwilling to try new things.

Sensory Threshold Examples

Now that we have a handle on what the sensory threshold is, let's discuss a few sensory threshold examples through our five primary senses.

Sensory Threshold vs Absolute Threshold

Let's compare similar terms: sensory threshold vs absolute threshold. The sensory threshold is not an exact measurement. One way psychologists measure our sensory threshold is by determining the absolute threshold.

Anything above the absolute threshold can be perceived on a conscious level while anything below the absolute threshold is considered subliminal and cannot be consciously perceived. Some messages may get through, but it is not enough for our brains to be consciously aware of them.

Another way sensory threshold is measured is by the difference threshold or just a noticeable difference (jnd).

Take the following image, for example. At which point do you notice a color difference?

Fig. 2, color gradients highlight thresholds, Commons.Wikimedia.org

But is the difference threshold the same for every one of our senses? In the late 1800s, German physician Ernst Weber discovered the answer is no. Weber found that each of our senses has a specific difference percentage (not value) that is required in order for it to be possible for us to detect a difference. This finding is now called Weber's Law.

Sensory Threshold Experiment

Psychologists perform several sensory threshold experiments that can help determine the absolute threshold. For example, to determine a person's absolute threshold, researchers will play a single tone at various volumes and track how frequently a person can hear the tone. Remember, the lowest point at which a person can hear the tone 50% of the time can be considered the absolute threshold.

Researchers also conduct experiments to test subliminal sensory information and whether or not it unconsciously affects us.

To test subliminal messages, a pleasant or unpleasant image is quickly displayed on the screen before showing an individual's profile picture. The image just before the profile picture is not consciously perceived and is subliminal.

The participants are then asked to judge each individual favorably or unfavorably. Profiles following a pleasant image were more likely to be perceived favorably while those following an unpleasant image were more likely to be perceived unfavorably.

The process of presenting several subliminal messages to influence a person's behavior or decisions is called priming. Our world is full of priming through subliminal messages.

² Lowman, D. K. (2009, September 24). Understanding sensory processing: Looking at children ... - infantva.org. itcva.org. Retrieved August 4, 2022, from https://infantva.org/documents/copa-conf2008-sensory-koontz.pdf