The spread σ in the final settings of repeated adjustment processes is often taken equal to (or at any rate proportional to) the difference limendas found by a method of forced choice. A detailed investigation into the adjustment process shows that this is not necessarily correct. In principle,σ = (ξd)12, where ξ is the (average) move length in the adjustment process. This implies that σ is proportional to the square root of the difference limen if σ is constant. Normally, however, the subject intuitively chooses ξ roughly equal to13d, so that σ∼dholds in most practical cases. These ideas are applied to binaural frequency discrimination of sinusoids, the duration of which is variable.