An impeller pump with thermostatically adjustable guide vanes is suitable for use as an automotive coolant pump. A judgment standard storage section stores a plurality of judgment standards according to the number of occurrences of the specific event-related potential. The billiard ball holder includes an opening to the elongated central space such that billiard balls can be inserted into the central space through the opening. A penalty may be assessed if the first plurality of products does not correspond to the second plurality of products. At least one polarization means is provided in the illumination beam path andor in the imaging beam path, by which at least one polarization means the light of the respective beam path can be converted into a predeterminable polarization state.