Note 442 — Chapter XIII · (continued 2)

The judgment becomes easier if the two couples of terms have one member in common, if a—b and b—c, for example, are compared. This, as Stumpf says (Tonpsychologie, i, 131), is probably because the introduction of the fourth term brings involuntary cross-comparisons with it, a and b with d, b with c, etc., which confuses us by withdrawing our attention from the relations we ought alone to be estimating.