Prediction proportion judgment cyclic power models as used in Hollands and Dyre and Barth and Paladino . a) 1-cycle model, with no central reference point; b) 2-cycle model, with one central reference point. In both a) and b) β is the exponent in the power function describing the relationship of psychological to physical magnitude. Legend: Green β = 0.1, Aqua β = 0.3, Blue β = 0.5, Red β = 0.7, Black β = 1.0. NB. When β = 1, the function is linear.