Subject differences in exponents of psychophysical power functions for inferred, remembered, and perceived area

Abstract

Data are presented from two magnitude estimation experiments in which the geographical areas of Brazilian states were judged. In Experiment 1 observers estimated the areas of the states in three conditions: in the presence of a map (perceived area), using memory following study of a map (remembered area), and using only general knowledge of Brazilian geography (inferred area). The results showed that the psychophysical power law describes well the inferred, remembered, and perceived magnitude estimates of areas of states. As had been found previously for areas of states, the remembered exponent approximated the square of the perceived exponent. Experiment 2 examined the correlations of the power functions exponents for observers who estimated areas of states on two sessions separated by an interval of 1 month. As in Experiment 1, observers estimated the areas from inference, from memory following study of a map, or in the presence of a map. Again, comparison of remembered and perceived psychophysical functions showed that for both sessions the remembered exponent was equal to the square of the perceived exponent. Since the correlations between Sessions 1 and 2 were fairly high and positive, the results also showed that all modes of judgments manifest temporal stability for an interval of at least 1 month between sessions. Stable individual differences can be shown for the exponent of the psychophysical power function for magnitude estimates of inferred, remembered, and perceived area. Although the exponent varies from one individual to another, the power function accurately describes the data of all observers in all conditions.