# 49. Manipulation of bias and heuristics in decision making ## 49.5. Methodology/Refinements/Sub-species ### 49.5.14. Contrast effect This is the enhancement or diminution of a weight or other measurement when compared with a recently observed contrasting object. So, asking someone to estimate the weight of a chair by comparing it with that of a feather or a car will illicit firm comparisons. Asking a victim for a weight estimate of two similar chairs will illicit uncertain responses. Here, weight is a synonym for any form of measurement, like time, distance, difficulty, beauty even. People living in countries where the citizens tend to be tall, find their fellows to be of normal height, and everyone of more average height is seen as "short". This is because "tall" is normal for them. The manipulator can use the recent quantitative experiences of a victim to prejudice their judgment of their present experience.