Using our eyes we obtain information about the direction in which we are driving. Our eyes send that information to the primary visual cortex, which is located at the back of our brain. The primary visual cortex transmits information across an entire network of visually-specialized areas. Each of these areas performs operations that extract useful information from the visual input. These operations are essential because the raw visual input is unsuitable for the rest of the brain to take action (turning, braking, stopping, accelerating, …).
To determine the steering direction, there are two types of useful visual information:
These two types of visual information are now discussed in more detail.
1. Our position in relation to relevant objects in our environment
In order to determine our position in relation to objects in our environment, we must first recognize these objects. To this end, our brain has a range of areas that extract increasingly more specific information from the raw visual input. This process begins with brain regions that can only detect the direction of lines, then areas that can detect corners and shapes, and finally areas that specialize in very specific objects such as houses, utensils and faces. This series of brain regions is called the “What-route” because the visual information relates to what we perceive.
In this video the What-route is explained in detail, and here you find the content of this video as an animation.
2. The speed and direction with which the environment moves past us
The second type of visual information on which we base our steering direction is the speed and direction with which the environment moves past us. When riding a bicycle, this mainly concerns the movement that occurs because the cyclist moves within a stationary environment. The type of visual information generated by this movement is referred to as “optic flow”, and in the video below this phenomenon is illustrated by means of a point cloud.
For observing optic flow, our brain has specialised areas that extract this movement information from the raw visual input. These brain areas belong to the so-called “Where-route”, which takes its name from the fact that the visual information relates to the location of the objects (and not their identity). Optic flow gives the brain specific information about the change of location of those objects (i.c., their speed and direction).
In this video the Where-route is explained in detail, and here you find the content of the video as an animation.