The perception of reality that each individual has is created through information received by sensory receptors present in the human body. This information is transferred to the brain in the form of electrical signals, which it receives and interprets as experiences.
Absolute Threshold vs Difference Threshold
The main difference between absolute threshold and difference threshold is that absolute threshold is the minimum amount of stimulation that one can interpret or perceive, whereas, difference threshold is the minimum amount of change required in the intensity of a stimulus, for someone to be able to interpret a difference.
Psychophysicists often use the term ‘threshold’ while dealing with the subject of sense and perception. Threshold means the limit values in which an individual perceives or interprets something. For example, there is a minimum value at which someone can perceive a certain stimulus. This value is a threshold.
Comparison Table Between Absolute Threshold and Difference Threshold
| Parameters of Comparison | Absolute Threshold | Difference Threshold |
| Meaning | Absolute threshold is the minimum amount of stimulation that an individual can interpret or perceive. | Difference threshold is the minimum amount of difference in the intensity of a stimulus, for someone to be able to interpret a change. |
| Condition of stimulus | There is no change in the intensity of the stimulus while determining the absolute threshold. | There needs to be a change in the intensity of the stimulus while determining the difference threshold. |
| Determined value | The determined value specifies the smallest amount of intensity. | The determined value specifies the smallest amount of change in intensity. |
| Distinctness | Absolute threshold varies among different people, and between people and animals as well. | There is only a slight variation between the difference threshold of different people. |
| Example | The minimum distance at which a person can see a candle burning clearly. | The minimum amount of difference in the distance required for a person to notice the change in position. |
What is Absolute Threshold?
Initially, according to the studies of neuroscience and psychophysics, absolute threshold referred to the minimum intensity level of a stimulus at which a person’s sense receptors could perceive it. For example, the lowest volume at which one can hear, the shortest distance till which one can see clearly, the smallest amount of concentration of a fragrance that one can smell, and so on.
However, it was later observed that internal or external factors could influence the absolute threshold of a person. For example, an individual can taste food easily when the level of health was good. But on catching a slight cold, the intensity of taste while eating the food decreased. This made it difficult to determine the individual’s absolute threshold as health conditions are prone to change at different times.
To counter this problem, it was decided to change the definition and method of determining one’s absolute threshold. Now, physicists would carry out multiple tests on a person over a certain period. The value which came out to be true fifty percent of the time would be referred to as the absolute threshold of the person.
Presently, absolute threshold is the smallest amount of intensity at which an individual can perceive a stimulus fifty percent of the time. The idea which influences this modification is known as the single detection theory. It states that there is no single absolute threshold because of other influencing factors.
What is Difference Threshold?
Difference threshold is the minimum amount of difference required in the intensity of a stimulus for an individual to be able to perceive or detect a change. It is also referred to as ‘Just Noticeable Change’ (JND). Like absolute threshold, a person should be able to detect the same value at least fifty percent of the time.
Some examples of difference threshold are – the smallest increment in the intensity of sound for one to detect a change in the television’s volume, the minimum amount of distance at which a person can see an object clearly, the minimum amount of heat required for one to feel that the food is hot, and so on.
Weber’s law is a significant law of psychology that quantifies the detection of change regarding a certain stimulus. According to the law, as the intensity of a stimulus increases, it becomes more and more difficult to perceive a change or difference. For example, if the volume of a television set is already very high, it would be difficult for a person to detect whether or not the volume has been increased further.
To have a clear understanding of Weber’s law, imagine a television set which is playing at volume 5. Now, if it changed to volume 10 (an increase of 100%), the difference in sound will be noticeable. However, the change in sound between volume 50 and 55 will not be of the same value. For a person to be able to notice it, volume 50 will need to be changed to volume 100 (an increase of 100%).
Main Differences Between Absolute Threshold and Difference Threshold
- Absolute threshold is the minimum amount of intensity required for one to be able to detect a stimulus while difference threshold is the minimum amount of difference in intensity required for one to be able to detect a change.
- Unlike difference threshold, absolute threshold does not involve any change in the intensity of the stimulus.
- Absolute threshold determines the minimum value of intensity while difference threshold determines the value of change of intensity.
- Absolute threshold varies largely from person to person as well as animals, whereas, there is only a slight variation in the difference threshold of different people.
- Absolute threshold is the minimum amount of volume at which a person can detect sound. On the other hand, difference threshold is the minimum amount of change in the volume for a person to detect it.
Conclusion
Absolute threshold and difference threshold are important concepts of sense and perception. The difference between the two can be understood by the fact that absolute threshold determines the minimum value of intensity while difference threshold determines the minimum value of change of intensity.
References
- https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1750-3841.2011.02589.x
- https://ieeexplore.ieee.org/abstract/document/7476866/