Introduction to Sensation || Sensation and Perception || Bcis Notes

Introduction to Sensation || Sensation and Perception || Bcis Notes

Introduction to Sensation

Sensation refers to the activation of receptors. Receptors are the basic structure of sensation. It is the process through which we detect physical energy from the environment and encode it as a neural signal. The sensory process starts at the entry-level so psychologist refers it as bottom-up-processing. Humans’ life will be a failure without an introduction to sensation.


Sensation refers to the activation of the receptors. Receptors are the basic structures of sensation. It is a physical feeling or perception resulting from something that happens to or comes into contact with the body. The sensory process starts at the entry-level so psychologist refers it as bottom-up-processing.

Attributes of Sensation :

 The main attributes found in sensation are Quality, Intensity, Duration, Extensity, and Local sign. Almost most of the sensation is similar to each other on the basis of their general characteristics.


Different sensations have different qualities. Even in visual sensation, there are different colors like red, blue, green, etc.   Likewise in taste sensation also known as gustatory sensation, it may be sour, bitter, or salty. In a similar manner, other sensation also has unique qualities.


The strength or degree of a sensation is the second characteristic. It differs from one to another. For example, bright color has different shades ranging from dark red to light red. At a dance party, we like high sound whereas we like dim sound while reading.


The appearance moment of a stimulus signifies its duration. It may be for a longer or a shorter time. For example, people at present know more about AIDS than it was actually found out.


It is the area that sensation occurs. For example, the sound of air-plane is less when it is in the air than at nearby places.

5.Local sign:

It is the sign that is distinguished on the basis of the spot stimulation. For example, touch on the face gives a different sensation than in the leg.


The relationship between attributes of the sensation and characteristics of the stimulus is studied by psychologists. Psycho means mind or experience and physics means a physical aspect. Combining these two terms together explains psychophysics as the relationship between physical stimuli and our psychological experience.

Sensory threshold:

The lowest value of a stimulus that can produce a sensation is called the sensory threshold. Two types are as follows:

  • Absolute threshold
  • Differential threshold
Absolute Threshold Differential Threshold
The smallest intensity of the stimulus to be noticed by the receptor is called the absolute threshold. It is the amount of stimulus that must be added or subtracted from the existing stimulus for a person to notice a difference.
The German word for sensation is Reis and for threshold is Limen(Ries limen or RL). The minimum notice to be noticed as a difference is called a differential threshold.
Example; RL for light, smell, taste, etc. Example; making tea to calculate the amount of sugar, milk, etc.

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