In discussion of sensation in the field of psychology, the absolute threshold refers to the smallest perceptible stimulus that causes a sensation. A light that is just barely bright enough to see or a touch that is the lightest touch you can feel is at the absolute threshold of sensation. The difference threshold refers to the smallest possible change in a stimulus that will register in your sensations as a difference. These thresholds are important because they define a person's direct experience of the world.
Adabtability of Sensation
Humans also have the ability to adapt their sensations to more efficiently gather relevant information from their settings. For example, when there are many overlapping or potentially overwhelming stimuli, the human brain can use "signal detection" to filter out noise and enhance perception of relevant details, as when you hear your name spoken in a noisy room or glance around a room for red objects. Similarly, a constant sensation will become less vividly noticed over time, such as when you stop noticing a background noise, to make room for novel stimuli that may be more relevant.
Perceptions allow people to create meaningful patterns out of the sensations they experience. Gestalt theory describes four ways that the brain groups similar objects to make sense of them: similarity (grouping like objects), proximity (grouping objects that are near each other), continuity (recognizing patterns) and closure (filling in gaps in familiar shapes or patterns). Without this perceptual ability, the world would seem chaotic and it would be difficult for people to make sense of their experiences or decide how to act.
Importance of Sensation and Perception in Daily Life
Sensations and perceptions shape the way humans see the world. The ability to take in information from reality and process it in meaningful ways allows people to form a worldview that helps them to understand life and make wise decisions. A lack or loss of sensations, such as blindness or deafness, creates a gap in the experience and makes it harder to understand events fully. A perception failure leads to misinterpretation of life and an inability to respond adequately to the current situation.