The detection of multiple manual interactions upon a touch-pad is shown. Drive lines intersect a scan lines and each intersection between a drive line and a scan line includes an element of variable resistance. A scanning processor energises the drive lines and monitors the scan lines. The scanning processor is configured to identify positions of manual interaction, validate identified positions to identify potentially erroneous positions and remove positions identified as erroneous. However, removed positions are re-introduced when they are not in the vicinity of other identified positions.