The term absorption is used in a few different ways. In sensation and perception absorption refers to the physical process of absorbing light, such as the way light is absorbed by water until there is only darkness. This is caused by refraction while passing through water molecules. This is why shallow water is translucent with a blue/green tint (because red light is the first frequency lost in refraction) while, as more and nore light is refracted, the ocean becomes darker the deeper you go until all the light is "used up". In biological usage, absorption can refer to the reuptake of chemical neurotransmitters in to the neuron. In personality psychology, absorption refers to a personality trait in which an individual becomes completely involved and entranced with their own fantasical thoughts and images, being realted to fantasy-prone personality. Originally researached by Auke Tellegen, the Tellegen Absorption Scale (TAS) is the most common measure used to identify absorption levels.