The absolute threshold is the minimum stimulation level an organism needs to sense a stimulus – such as sound, smell, light, touch, and taste. It is the lowest point at which people or animals can detect something around them.
Grasping how humans take in and interpret sensory information is fundamental to understanding the psychology of perception, for which knowing the absolute threshold plays a key role.
As an example of absolute threshold, we can look at the faintest noise a person can perceive. This number may range from 20-30 decibels and varies depending on a person’s particular hearing capabilities.
In psychology, the concept serves as a fundamental concept for understanding the perception of different stimuli.
Absolute Threshold Definition
An absolute threshold is a psychological concept that explains the least amount of stimulation needed for an organism to detect it.
If even a faint stimulus surpasses the threshold level, then its perceivable by any living creature.
According to Harcum (2013), an absolute threshold is:
“…the minimum stimulus intensity that the particular person can detect as present” (p. 55).
For example, a person’s absolute threshold for smell is the faintest odor they can identify.
Gerrig (2015) writes that an absolute threshold is:
“…the minimum amount of physical energy needed to produce a reliable sensory experience” (p. 125).
The significance of this concept is enormous when it comes to comprehending how humans and animals process information.
This critical knowledge addresses why people are aware of some sensations and oblivious to others, thereby allowing us to comprehend the correlation between stimulus and response.
In simple terms, an absolute threshold is the lowest intensity of stimulation that a person can perceive. It is useful when assessing the sensory abilities of an individual, as well as in studying the psychology behind perception.
Absolute Threshold Examples
- Hearing Threshold: When getting a hearing test, a person’s absolute threshold is the quietest sound they can hear. Depending on their hearing capabilities, it can range from 20-30 decibels. Hearing thresholds in humans also tend to differ based on age; and they differ between animals.
- Sense of Smell: The threshold for smell is the faintest scent a person can detect, based on their own individual sensitivity to odors. For example, a drop of perfume in a swimming pool can be perceived as an absolute threshold.
- Sense of Sight: A person’s absolute threshold for sight is the faintest light they can see, which is measurable in terms of lumens. A car’s headlights or a streetlight when all other lights are off are great examples.
- Sense of Taste: A person’s absolute threshold for taste is the weakest flavor they can recognize, ranging from one part per million to several thousand parts per million in magnitude. For example, the amount of salt added to the food until it can be tasted is an absolute threshold.
- Sense of Touch: Everyone has a unique ability to sense the lowest amount of pressure when touching an object. If someone puts a hand on an electric stove before it turns hot, they may not feel the heat due to a high absolute threshold. When the temperature rises, the point at which someone feels the heat is their threshold for touch.
- Temperature: Each individual has a specific absolute threshold for temperature, indicating the minimum level of warmth or cold they can sense. This range may vary between 0.5 and 4 degrees Celsius. A light breeze on a summer day or the chill in the air on a winter morning are both examples of absolute threshold temperatures.
- Pressure and Touch: The absolute threshold of pressure is a person’s minimal level of physical touch they can experience, spanning from 0.5 to 4 pounds per square inch on the epidermis. For instance, a person may or may not perceive the weight of a feather on their skin.
- Sensing Motion: Everyone has a unique ability to detect motion, and this capability is referred to as an absolute threshold for motion. Generally, the least amount of movement that human beings can perceive falls within 0.3-5 centimeters per second in terms of travel speed. A slow-moving river or a gentle breeze are both examples of this.
- Balance: When someone is standing or sitting still, the minimal amount of tilt they can detect is known as their absolute threshold for balance. Depending on the person, this may range anywhere from 1 to 4 degrees around any axis. For instance, the difference between standing upright and leaning slightly to one side is an example of an absolute threshold.
- Pain Threshold: Pain is a subjective experience, and the lowest level of pain intensity that one can perceive has an absolute threshold. It may vary from person to person; for some, it may be 0 on a scale of zero (pain-free) up to 10 (excruciatingly painful). For example, the sting of a pinprick may be perceived as an absolute threshold for those with a high pain tolerance.
Origins of the Absolute Threshold Concept
The concept of absolute threshold was first introduced by the 19th-century German psychologist Gustav Fechner. He developed a theory known as the Weber-Fechner Law, which posited that the perception of stimuli is related to the magnitude of its energy.
Weber-Fechner Law states that the magnitude of a stimulus must increase exponentially to be perceived by the human mind, meaning that there is a certain point at which people are unable to detect a difference in the intensity of a stimulus (Algom, 2021).
This point is known as an absolute threshold, which varies from individual to individual depending on several factors, such as age, gender, and overall health.
In other words, a person’s absolute threshold is the weakest stimulus they can detect due to the amount of energy it emits. It was a breakthrough in psychology and has since been applied to many fields.
Fechner, however, sought more than the absolute threshold. He was determined to uncover how various levels of stimulus intensities matched with their corresponding sensation values—which went beyond simply detecting the lowest level of conscious sensation (Roeckelein, 2006).
Subsequently, he postulated the idea of a differential threshold: the minuscule level of change in a stimulus that can be noticed.
Absolute Threshold vs. Difference Threshold
An absolute threshold is the lowest level of stimulation a person can detect. In contrast, a difference threshold is the minimum amount of change in an existing stimulus that a person can detect.
Absolute thresholds are useful for measuring a person’s sensitivity to stimuli such as sight, sound, taste, etc. They indicate the weakest possible stimuli a person can detect and how it varies from individual to individual.
In contrast, difference thresholds are used to figure out the amount of change needed for someone to detect a distinction between two stimuli, referred to as “just noticeable difference” (JND) (Meilgaard et al., 2016).
The latter helps measure the level of sensitivity to change that someone possesses.
For instance, the change in volume between a whisper and a shout may be more significant than the JND for sound, meaning that most people can easily distinguish between the two.
Overall, absolute thresholds measure individual sensitivity to a given stimulus. In contrast, difference thresholds measure how much change needs to be made before it can be discerned.
Factors Influencing Absolute Threshold
Multiple factors can affect the absolute threshold, from the observer’s expectations and motivations to whether they are acclimated to the external stimulus.
Here are five of the most significant factors:
- Observer’s motivation: Human attention can significantly alter an individual’s absolute threshold. For example, those who are intensely motivated to detect a certain stimulus often possess a lowered threshold.
- Person’s expectations: A person’s stimulus anticipation can also affect their absolute threshold. For example, if a person anticipates loud noises, they may be more sensitive and detect them quicker. On the other hand, if someone is expecting softer noise, they will likely have a higher threshold to notice it.
- Acclimation: When an observer is exposed to a stimulus for any time, their absolute threshold can be impacted. If they become familiar with the stimuli, it could lead to a lowered threshold. For example, after being acclimated to something like the clock’s ticking sound for several minutes, a person may begin noticing and detecting it.
- Age: The observer’s age can affect their absolute threshold. Generally speaking, younger observers tend to have lower thresholds than older observers. It is because the former are more sensitive to stimuli and more open to new experiences, making detecting faint stimuli easier.
- Overall health: The overall health of the observer can affect their absolute threshold. For instance, someone who is not feeling well or has poor vision may have a higher threshold than someone who is healthy and has perfect sight. Besides, some may suffer from sensory processing disorder, making them less sensitive to certain stimuli.
An absolute threshold is an important concept in psychology. It helps measure a person’s sensitivity to various stimuli, such as sight and sound.
Compared to a difference threshold, an absolute threshold measures the lowest level of a stimulus that can be detected. The former, in contrast, measures the minimum amount of change needed for someone to detect a distinction between two stimuli.
Multiple factors such as motivation, expectations, acclimation, age, and overall health can influence an individual’s threshold.
Understanding these elements can help identify individual differences in sensitivity and make it easier to compare the thresholds of different people.
In addition, this knowledge can be used to understand behavior and psychology better and develop treatments for sensory disorders.
Algom, D. (2021). The Weber–Fechner law: A misnomer that persists but that should go away. Psychological Review, 128(4), 757–765. https://doi.org/10.1037/rev0000278
Gerrig, R. J. (2015). Psychology and life. Pearson.
Harcum, E. R. (2013). Principles of psychology in religious context: Psychological and spiritual origins of human behavior. Hamilton Books.
Meilgaard, M. C., Civille, G. V., & Carr, B. T. (2016). Sensory evaluation techniques. Crc Press, Taylor & Francis Group, CRC Press Is an Imprint of the Taylor & Francis Group.
Roeckelein, J. E. (2006). Elsevier’s dictionary of psychological theories. Elsevier.