A receptive field is the area within which a cell is able to perceive information. Though the term is still used most often with regards to the sense of sight, there are receptive fields associated with sound, smell, and touch as well. The receptive fields of sensory cells differ from cell to cell and from region to region. The term was first used in 1906 after experiments using light were conducted that demonstrated the receptive fields of various neurons on the retina.
The term receptive field is most often used when discussing the sense of sight. The size of the receptive field of the cells in the retina is measured in degrees and ranges, depending on the location of the retinal cell, from a fraction of a degree to about ten degrees. The cells on the edges of the retina have a wide receptive field, whereas the cells toward the center of the retina are able to gather information from only a small area. This results in the ability to focus on only a small area at the center of the field of vision, while being able to perceive a wide and yet unfocused periphery.
The receptive field of somatosensory neurons can also be measured. These neurons are located in the skin and respond to different stimuli, including temperature, pain, touch and vibration. Regions that are more sensitive, such as the fingertips, have a smaller receptive field than less sensitive regions. The neurons in the fingertips will only perceive stimulation in a small region of about 0.2 inches (5 mm) around them before the information is picked up by other neurons. This allows humans to discern a great deal of information about an object from the tips of the fingers.
In terms of auditory processing, the receptive field of particular neurons is measured by their ability to discern between different sound frequencies. The location of the source of a sound wave can also play into the receptive field of the auditory system. Though little has been studied with regards to the receptive field of olfactory receptors, these too have a receptive field.