Although the tilt aftereffect has been studied for many years, a fully satisfying explanation has yet to be established. The prevailing theory is based on lateral inhibitory interactions between orientation detectors in the primary visual cortex. This theory can account for the angle repulsion effects found at small angle differences between test and adaptation figures. However, the angle attraction effects found for larger angle differences have not yet been explained satisfactorily. A detailed neural model that includes modifiable lateral connections, such as that presented in the next chapter, allows the lateral inhibitory theory to be studied in more detail. Subsequent chapters will show that tilt aftereffects, both direct and indirect, arise out of the same processes responsible for self-organization of such a model of orientation detectors in the primary visual cortex. Unlike TAE models which are merely a mathematical fit to the data, the model in this thesis is a general explanation of the organization and function of the primary visual cortex.