Unfortunately it isn't really obvious. Let's approach it a different way. Assume that some event is going to happen in the future. Call the event Y. Further assume that Y can be expressed as a function of X, such as in the linear equation Y = a + bX. a is a constant, say the current situation relevant to event Y, and b is a coefficient that fits X to Y.
a is constant, because it is the present situation and cannot change. Say the event Y is a decision, a Yes/No decision. The decision will be "no" until the function a + bX exceeds a certain amount, then it becomes "yes." As an example, Y is a decision whether or not to vote 10 years from now. a = whether or not the person voted in the last election, X is a measure of the degree of ideological difference between the 2 candidates running in any given election, and b is the decision maker's level of awareness of the ideological difference. So, intuitively, the decision maker will vote when he is sufficiently aware of a sufficiently large ideological difference between candidates to move the decision from no to yes.
Now, assume all of the above, AND that God has exhaustive and perfect knowledge of the decision makers decision and then that He does not have this exhaustive and perfect knowledge. Given that we are able to describe the decision maker's action perfectly without reference to God's foreknowledge, will the behavior differ if the assumptions change from foreknowledge to non-foreknowledge?