For many feelings, the linear measure is often ineffective, we can grant that to the author to highlight this fact. In my experience (read: not a specialist, a

For many feelings, the linear measure is often ineffective, we can grant that to the author to highlight this fact. In my experience (read: not a specialist, anecdotal data point), I relate to the 2-scale described here and more: the lack. Typically, the lack of [feeling] or its opposite is as much a sign as its abundance. To exemplify, being (un)happy is what one might call a positive action: you DO feel (un)happy. In that sense, not feeling any hapiness or unhappiness is putting yourself in an emotional void, which calls for action in a much different way that treating happiness VS unhappiness. --- Edit: to conclude: Hence, the scale I'd like to propose is, for some definition of happiness and probably many other feelings: * measure of lack, presence, abundance of effective emotions * measure of wanted feeling * measure of unwanted feeling