[Tex/LaTex] vertical alignment in table cells

Question

I am trying to center vertically the text in table cells but I can't make it work with my current table. This is the setup I have so far using the m argument, which I attempted by looking here.

\documentclass[10pt,a4paper]{article}

\usepackage[usenames,dvipsnames,svgnames,table]{xcolor} % use color
\usepackage{booktabs} % commands for table rules
\usepackage{tabularx}
\usepackage{lipsum}

\newcommand{\scell}[1]{\cellcolor{black!25} \bfseries #1 }
\newcommand{\slcell}[1]{\cellcolor{black!25} #1 }


\begin{document}

\begin{tabular}{|>{\arraybackslash}m{1.8cm}|>{\centering\arraybackslash}m{3.5cm}|>{\centering\arraybackslash}m{2.8cm}|>{\centering\arraybackslash}m{2.8cm}|>{\centering\arraybackslash}m{2.8cm}|}
\hline 
& \textbf{Given names}  &  \multicolumn{3}{c|}{\textbf{\centering Testing}} \tabularnewline
\hline
\multicolumn{5}{|l|}{  \scell{Category 1}}   \tabularnewline
\hline 
 & Person 1  & \multicolumn{3}{p{9cm}|}{\lipsum[1] }  \tabularnewline
\hline 
\end{tabular}


\end{document}

This gives me the following result:

Answer 1

Use \multicolumn3{m{9cm}}{…} instead of p{9cm}. As your table is too wide to fit the margins, I took the opportunity to change it using tabularx. Also note the usenames option for xcolor is obsolete: it's the default now.

\documentclass[10pt,a4paper]{article}
\usepackage[showframe]{geometry} %
\usepackage[dvipsnames,svgnames,table]{xcolor} % use color
\usepackage{booktabs} % commands for table rules
\usepackage{tabularx}
\usepackage{lipsum}

\newcommand{\scell}[1]{\cellcolor{black!25} \bfseries #1 }
\newcommand{\slcell}[1]{\cellcolor{black!25} #1 }


\begin{document}

\noindent
\begin{tabularx}{\linewidth}{|>{\arraybackslash}m{1.5cm}|>{\centering\arraybackslash}X|>{\centering\arraybackslash}m{2.8cm}|>{\centering\arraybackslash}m{2.8cm}|>{\centering\arraybackslash}m{2.8cm}|}
\hline
& \textbf{Given names} & \multicolumn{3}{c|}{\textbf{\centering Testing}} \tabularnewline
\hline
\multicolumn{5}{|l|}{ \scell{Category 1}} \tabularnewline
\hline
 & Person 1 & \multicolumn{3}{m{9cm}|}{\lipsum[1] } \tabularnewline
\hline
\end{tabularx}

\end{document}