LENGTH OVERESTIMATION BIAS AS A PRODUCT OF NORMATIVE PRESSURE ARISINGFROM ANTHROPOCENTRIC VS. GEOCENTRIC REPRESENTATIONS OF LENGTH

Three exploratory studies examine adjustment of the cognitive system t o the change or innovation introduced by the metric system. These stud ies begin from the supposition that two norms of reference may coexist when non-experts have to estimate the length of a line: The anthropoc entric, the more ancient and natural norm, and the geocentric metrical system, the more modem and external to the subject. The fine discrimi nation provided by the decimal metric system is often unnecessary in d aily life, and anthropomorphic measures (the finger, the span, the ste p) may be sufficient to estimate the length of objects. The newer deci mal metric system has not yet displaced the ancient anthropomorphic sy stem, and the coexistence of these two systems, according to circumsta nces, can be an important source of cognitive bias. The research hypot hesis is that, compared to units in the anthropomorphic system, the mm and the cm embody the normative property of being ''smaller'', a prop erty that may result in a tendency to overestimation in absolute estim ations of length. it is also anticipated that the higher the probabili ty of error in a task (e.g., the more mm or cm a line has, or the less precise are the available perceptual cues), the greater the bias towa rds length overestimation.