I need to create the following table in LaTeX and I just cannot seem to get it right.

The text inside the cells is not centered correctly and the same goes for the “Eye movements” cell. Could any of you see what I doing wrong?
\begin{tabular}{ccc|c}
& & \multicolumn{2}{c}{\textbf{Response}} \\
& & unnatural & natural \\ \cline{3-4}
\multicolumn{1}{c}{\multirow{2}{*}{\begin{sideways}\textbf{Eye movement}\end{sideways}}} &
\multicolumn{1}{c|}{\begin{sideways}unnatural\end{sideways}} & 1 & \multicolumn{1}{c|}{2} \\ \cline{2-4}
\multicolumn{1}{c}{} &
\multicolumn{1}{c|}{\begin{sideways}natural\end{sideways}} & 3 & \multicolumn{1}{c|}{4} \\ \cline{3-4}
\end{tabular}
Thanks for the pointer. I finally made it work with the following code: