The theory not only explains the first order effects which are dominant in angle range of to , but also accounts for the second order effects which can be seen in to range, where the sign of the effects is reversed.
If one includes the second order effect, it can be considered as an effective cross-orientation (90 degrees) interaction of range and the strength of decorrelation feedback . For the orientation adaptation, the Equation 11 is now
For the orientation contrast, the Equation 13 is now
The comparison of the theoretical predictions with the experimental data is shown in Figure 6. The parameters used are for both effects and and for the orientation adaptation and orientation contrast respectively. Note that for both effects, and is much smaller than and thus for second order effect.
Figure 6: Quantitative comparison of the theoretical predictions with the experimental data of orientation contrast (left) and orientation adaptation (right). This figure includes second order effec.