Anchor Effects and the Estimation of Graduated Circles and Squares

An experiment was conducted to evaluate the relative effectiveness of apparent value scaling and the use of several legend symbols in eliminating the underestimation of symbol size ratios. It was hypothesized that estimates of symbol size are based on a neutral reference point, called adaptation level (AL), and that legend symbols act as anchoring stimuli by pulling the AL in the direction of the legend symbol, a process called assimilation. When the AL is shifted, so is the entire judgment scale. Thus, a small legend symbol tends to yield underestimations and a large legend symbol, overestimations. When several legend symbols are used, the AL shifts with each symbol allowing more accurate estimates. The results of the experiment indicate that apparent value scaling does not compensate for the anchor effects of assimilation and that anchor effects occur with both circles and squares. In the case of both circles and squares the role of AL in explaining the anchor effects was supported. The use of several l...