Sensation is the function of the low-level biochemical and neurological events that begin with the impinging of a stimulus upon the receptor cells of a sensory organ. It is the detection of the elementary properties of a stimulus.[1]
Perception is the mental process or state that is reflected in statements like "I see a uniformly blue wall", representing awareness or understanding of the real-world cause of the sensory input. The goal of sensation is detection, the goal of perception is to create useful information of the surroundings.[2]
In other words, sensations are the first stages in the functioning of senses to represent stimuli from the environment, and perception is a higher brain function about interpreting events and objects in the world.[3] Stimuli from the environment are transformed into neural signals which are then interpreted by the brain through a process called transduction. Transduction can be likened to a bridge connecting sensation to perception.[citation needed]
Gestalt theorists believe that with the two together a person experiences a personal reality that is other than the sum of the parts.
Loss of sensation[edit]
Many types of sense loss occur due to a dysfunctional sensation process, whether it be ineffective receptors, nerve damage, or cerebral impairment. Unlike agnosia, these impairments are due to damages prior to the perception process.
Vision loss[edit]
Main article: Vision loss
Degrees of vision loss vary dramatically, although the ICD-9 released in 1979 categorized them into three tiers: normal vision, low vision, and blindness. Two significant causes of vision loss due to sensory failures include media opacity and