Motion aftereffect

Sutherland (1961) says motion is coded through spatial pattern coding. For one receptive field there are multiple cells, each of them coding for a different direction of motion. When something is static, all of the cells fire the same amount because none of them is more triggered than the other. When watching an object moving in a particular direction we become adapted to that and the motion coding cells specific to that direction of motion become unresponsive. Afterwards, when the person sees a stationary version of the image, the unresponsive cells do not contribute anything so the balance is pushed towards the cells for other directions of motion. This means the person perceives the object to be moving the opposite direction.

Mollon (1982) described the principle of adaptive independence as the cones being sensitive to light intensity based on the number of photons absorbed, and that the cones operate indpendently of each other so the photons absorbed by neighbouring cones have no influence. Adaptive independence makes it possible for a person to adapt to a particular direction of motion without any impact on the cells coding for the other directions, which leads to the imbalance when the stationary image is viewed after adaptation.

Visual neurons fire in response to the specific stimulus they are tuned to. In motion this is motion in a particular direction. This means that the initial movement that is adapted to is coded by a particular neuron.

Each cell only has one response, which is to fire, and the measurement of this is the firing rate. Pattern coding is the way these individual firing rates are intergrated to perceive motion or another feature like the angle. Each cell alone does not explain what is happening, but by seeing how much the cells respond relative to each other we can perceive the direction of movement.

When the motion is adapted to in one eye, there is some motion aftereffect seen with the other eye with a static second image. If the image after the motion adaptation is ambiguous (eg flickering) this increases the interocular transfer of the motion aftereffect. This means that the motion is being processed using a combination of visual and higher-order processes when the second image is static, but ambiguity makes it a higher-level process.