You rarely hear your next-door neighbors, but any time they cook, you can smell it through your entire house. How strong does the smell have to be for you to detect it? Or how loud would your neighbors need to be for you to hear them? This point is referred to as the sensory threshold.
- In this article, we will begin by defining the sensory threshold in psychology.
- Then, we will discuss the difference between the sensory threshold vs. the absolute threshold.
- Moving along, we will explore a few examples of the sensory threshold.
- We will understand what occurs when a person has a high sensory threshold.
- To conclude, we will take a look at a few sensory threshold experiments in psychology.
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.
Sensory threshold: the weakest energy output required for us to detect it.
The sensory threshold can vary for everyone and often relies heavily on our past experiences, beliefs, expectations, and values.
If you are expecting an important call, you will be more likely to hear the faint sound of your phone ringing from the other room than if you had no expectations at all.
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.
Signal detection theory predicts when and how we can detect a faint stimulus (signal) in the presence of background stimulation (noise).
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.
Taste: Johnny is baking a Mexican chocolate cake and wants to make sure he adds enough spices so it can be tasted through the chocolate. His sensory threshold is the point at which he begins to taste the cinnamon in the chocolate.
Hearing: Yolanda lives about ten blocks from the parade, while Randy is only two blocks from the parade. Randy can hear the crowd and the bands quite easily, while Yolanda can't hear anything. While on her way to Randy's house, Yolanda noticed she could start hearing the parade when she was about two blocks from Randy's house or four blocks from the parade. The amplitude around this point surpasses Yolanda's sensory threshold, allowing her to begin hearing the event.
Touch: Camilla tried to startle Annie by rubbing a feather on the back of her neck. Her prank, however, didn't work because Annie did not feel the feather, suggesting the touch did not reach Annie's sensory threshold.
Sight: From far away, Zach can't see the little spider on his bedroom ceiling. However, as the spider crawls down the wall next to his bed, he can see it clear as day.
Smell: Lily's neighbor smokes cigarettes all day but can never smell them in her apartment. However, her neighbor often has several friends who also smoke, which is when the smell usually floods her apartment, crossing the sensory threshold.
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.
Absolute threshold: the lowest value of sensory energy required for us to detect it 50% of the time.
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).
Difference threshold or just noticeable difference (jnd): the minimum difference between two stimuli required for it to be detected 50% of the time.
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.
Subliminal Messages: sensory input that is below the sensory threshold that is received by the brain but not consciously perceived.
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.
A lot of commercials count on the concept of priming to motivate people to buy their products. You may not be paying much attention to the laundry detergent commercial that played before a YouTube video. You may have even had the volume down and skipped after 5 seconds. You didn't consciously note the brand of the commercial you saw. But later, when you go to the store to buy laundry detergent, the fact that you subconsciously noticed the brand influences your choice without realizing it.
Sensory Threshold - Key takeaways
- The sensory threshold is the weakest energy output required for us to detect it. The sensory threshold can vary for everyone and often relies heavily on our past experiences, beliefs, expectations, and values.
- Some of us will have a high sensory threshold while others may have a low sensory threshold. Sensory processing disorder is when an individual is on either extreme.
- Every one of our primary senses -- taste, feel, hear, see, smell -- have a sensory threshold.
- The absolute threshold is the lowest value of sensory energy required for us to detect it 50% of the time.
- Subliminal Messages: sensory input that is below the sensory threshold and is not consciously perceived.
1 Jiang, Y., Costello, P., Fang, F., Huang, M., & He, S. (2006). A gender- and sexual orientation-dependent spatial attentional effect of invisible things. PNAS, 103, 17048–17052.
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
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