What Is Lateral Inhibition?
What Are Photoreceptors?
What Is Lateral Inhibition?
How Does The Hermann Grid Work?
How Do Mach Bands Work?
What Are Light Contrasts?
How Does White's Illusion Work?
Some photoreceptors are activated when they detect light, while others are activated in the absence of light. These two types usually encircle each other and are spread throughout the retina creating receptive fields. The image to the right is a depiction of how photoreceptors and receptive fields are arranged.
These fields can be called either ON-Center or OFF-Center depending on whether the photoreceptors in the center region become activated in the presence of light.
Often, light can fall onto both light and dark photoreceptors causing the two regions to compete with one another. One part
of the receptive field wants to become active while the other part does not. This competitive interaction is called
Lateral Inhibition.
The next image depicts several examples of receptive fields responding to different patterns of light.
Field A is receiving light solely in the center of the receptor field causing the center photoreceptors to
become active. The surrounding photoreceptors are also active because they are not receiving light. Therefore the entire receptive
field is active. Field E is fully active as well.
Field B is experiencing an opposite effect. The surrounding photoreceptors are receiving light while the center photoreceptors are not. Therefore, the entire receptive field is not active. Field D is not active as well.
Fields C and F demonstrate light patterns affecting both light and dark photoreceptors. Light is
hitting the light photoreceptors causing them to become active, but it is also hitting dark photoreceptors stopping them from becoming
active. As a result, the two areas (center and surround) are competing with each other. For that reason, lateral inhibition can also
called center/Surround antagonism.
Because of this antagonistic nature of receptive fields, perceptual illusions can occur when we look at certain patterns. Take a look at The Hermann Grid.