When it comes to perception and detection of different forms of stimulation, the human brain has been found to have limitations, especially with the conscious mind.
The absolute threshold is a term that has been used to determine these limitations and it has helped researchers with discovering ways to ensure better perception and influence of the mind.
We look at the absolute threshold at length and the role it plays in our lives.
What is the Absolute Threshold
The absolute threshold is the lowest level of stimulus that a person can perceive using their senses such as sight, taste, hearing, touch, and smell (1).
It is often used in experiments, neuroscience, and even subliminal messages in determining if a stimulus is a subliminal stimulus or a supraliminal stimulus.
A subliminal stimulus is usually below the absolute threshold.
A supraliminal stimulus, on the other hand, is a stimulus that can be detected by the senses and perceived by the conscious mind and it is used in supraliminal messages and supraliminal priming.
A supraliminal stimulus is above the absolute threshold.
An example of an absolute threshold is where an experiment is carried out for the detection of light.
Volunteers can be placed in a room that is dark and then be exposed to different degrees of light. As they detect the light, the degree of light is recorded down. After a number of exposures, the lowest degree of light that they detect is the absolute threshold.
Although it may seem that the absolute threshold is fixed, it usually varies and depends on the conditions of the environment and the different alterations made on the receptors.
That is why it is said that the absolute threshold is the lowest level of stimulus that can be discerned 50% of the time.
The absolute threshold is also referred to as the Absolute Threshold Level (ATL), absolute threshold, sensation threshold, or detection threshold.
How the Absolute Threshold Works
There are different thresholds recorded with the different human senses.
The absolute threshold for vision
When it comes to vision, the absolute threshold is the lowest level of stimulus that a person can become aware of using their sight. Scientifically speaking, it is the number of photons that a person can be conscious of 50% of the time.
By being subjected to different forms of light from varying distances, the absolute threshold for your vision can be found. Although, it is worth noting that this can be affected by a number of factors such as strength, location, and distance of the stimulus, to name a few.
Being in a dark place for a long time also helps you detect light faster compared to trying to detect it immediately after leaving a well-lit place.
Since you have adapted to the darkness by being in it for a long time, you have a much easier time discerning lower degrees of light in the dark place.
When you leave a room or place with bright light and get into a poorly lit or completely dark room, it will be hard for you to see anything at first. But with time, you get used to the darkness and soon you start seeing shiny objects in the dark room, and then you are able to see a few things in there which are fairly bright.
The absolute threshold for smell
In the sense of smell, the absolute threshold is the lowest concentration level that a person is able to smell at least half of the time.
The threshold of smell can be determined by trying to smell perfume in a big room or in a house with a number of rooms. The lowest level of concentration of the perfume that can be discerned is the absolute threshold.
The absolute threshold for touch
For the sense of touch, the amount of force that is needed for you to feel something settling on a part of your body or rubbing against it is the absolute threshold.
An experiment done to determine this threshold can be recording the amount of force that is needed for you to feel the wing of a bee or a feather on a part of your body.
The absolute threshold for hearing
The absolute threshold for hearing is the lowest possible sound a person with a healthy functioning body can be able to detect 50% of the time when it is calm and quiet (2).
To determine the hearing threshold, the sound of a gong can be used at varying distances. The lowest sound that can be heard by a person when far from the gong is the absolute hearing threshold.
The absolute threshold for taste
The absolute threshold for taste is the lowest level of concentration a person is able to taste half of the time. Determining this aspect, solutions are mostly used.
For instance, water can be used and a drop of a bitter substance such as Quinine sulfate added to the water.
The lowest concentration of the bitter substance a person can detect using their sense of taste half of the time is the absolute threshold.
Factors That Affect the Absolute Threshold
The absolute threshold varies due to a wide range of factors. Here are some of the factors that affect it:
* For the sense of hearing – The threshold depends on many factors including duration of the tone and age. Research has shown that the younger a person is, the easier it is for them to detect low sounds and the older they get, the harder it is for them to do the same (3).
* For the sense of vision – The absolute threshold is affected by factors such as the location of a stimulus, the wavelength of a stimulus, the strength of a stimulus, duration of a stimulus, and the experience of adaptation to darkness.
* For the sense of smell – In the case of our previous example where you determine the absolute threshold using perfume, the factors that might affect could be the size of the room or the distance of the other rooms, the strength of the scent and the presence of other scents.
* For the sense of touch – The part of the body touched plays a huge role. For example, your bareback and face have a higher level of sensitivity than many other parts of the body.
Moreover, there are factors that affect the threshold on a larger scale. One of these factors is expectation. If you had the expectation of seeing, smelling, touching, and even tasting a stimulus, it would be possible for you to detect lower levels of it than you would if you didn’t have any expectations.
Other factors include your thoughts, levels of motivation, and personality (introvert or extrovert).
And as researchers keep studying this threshold, we will be able to better comprehend its role in different biological and psychological processes to help us improve ourselves and others.
Essentially, the absolute threshold allows us to discover our actual limitations as human beings to consciously perceive an external stimulus.
It is also the fine line between subliminal perception that allows for perceiving stimulation which is detected by the subconscious mind and supraliminal perception that allows for perceiving stimulation which is detectable by the conscious mind.
Any stimulation that is above the absolute threshold can be perceived by conscious awareness while any stimulation that is below the threshold cannot be perceived by conscious awareness. Instead, the subconscious mind makes the detection.