Our sense organs function with certain limitations that restrict our ability to perceive the external and internal world completely. While these organs collect first-hand information, they operate within specific boundaries that affect our sensory experiences.

The most evident limitations can be seen in our eyes and ears. Our eyes cannot see things which are very dim or very bright. Similarly, our ears cannot hear very faint or very loud sounds. The same is true for other sense organs also, indicating that all sensory receptors have inherent constraints.

As human beings, we function within a limited range of stimulation. For being noticed by a sensory receptor, a stimulus has to be of an optimal intensity or magnitude. The relationship between stimuli and the sensations they evoke has been studied in a discipline called psychophysics.

Sensory processes do not depend only on stimulus characteristics. The sense organs and the neural pathways connecting them to various brain centers also play a vital role. A sense organ receives the stimulus and encodes it as an electrical impulse. For being noticed, this electrical impulse must reach the higher brain centers.

Any structural or functional defect or damage in the receptor organ, its neural pathway, or the concerned brain area may lead to a partial or complete loss of sensation. Understanding sensations requires understanding the AL and DL of different types of stimuli.