We either instrument goalkeepers with a light - weight Carl Zeiss Cinemizer Plus head - mounted display ( HMD ) .
We either instrument use a projection screen for the visual stimulus presentation , i.e. , no additional hardware equipment restricts the goalkeepers ' freedom of movement .
We either instrument goalkeepers with a light - weight Carl Zeiss Cinemizer Plus head - mounted display ( HMD ) or use a projection screen for the visual stimulus presentation , i.e. , no additional hardware equipment restricts the goalkeepers ' freedom of movement .