ID	Identical, if the present stimulus is identical to the previous stimulus.
SM	Same magnitude, if it has the same magnitude, but not the same probability, as the previous stimulus.
SP	Same probability, if it has the same probability, but not the same magnitude, as the previous stimulus.
SV	Similar value, if both the magnitude and the probability differ from the previous stimulus but the expected value (their product) is close to the previous one (difference <0.31 drops and =0.2 on average).
DV	Different value, if both dimensions differ from the previous stimulus and the expected value is not close (>0.31 drops and =1.5 on average).