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.

The danger of trial-by-trial knowledge of results in perceptual averaging studies

“…However, areal stimuli (filled or unfilled circles) are typically used in perceptual averaging experiments (e.g., Ariely, 2001;Chong et al, 2008;Chong & Treisman, 2003, 2005a, 2005bDe Fockert & Marchant, 2008;. It is well known that if observers are asked to react to the "size" as opposed to the area of circles or spots, the representation is not linear with the physical area and follows a compressive power function with an exponent (according to Stevens's power law) on the order of 0.70 to 0.80 (e.g., Algom, Wolf, & Bergman, 1985;Chang, 1977;Crawford, 1971;da Silva, Marques, & Ruiz, 1987;Ekman, 1958;Flannery, 1971;Griffen, 1985;Hubbard, 1994;Kemp, 1988;Krider, Raghubir, & Krishna, 2001;Mashhour & Hosman, 1968;Rule, Curtis, & Markley, 1970;Stevens & Galanter, 1957;Stevens & strategies that satisfy the criteria by which the positive and negative feedback are computed. These strategies could be direct (such as computation of a value based on sampling a small number of items) or indirect anchor and adjust strategies, as suggested in the present data with the harmonic mean or RMS feedback.…”

Recalling Taste Intensities in Sweetened and Salted Liquids

“…Stevens' power function exponents that are based on memory are generally smaller than those .based on perception (Kerst and Howard, 1978;Algom et aL, 1985;Da Silva et aL, 1987). Based on the findings of Moyer et al (1978Moyer et al ( , 1982, this results from overestimation of memorial intensities at low stimulus strengths; the perceptual and memorial power functions intersect only at very high stimulus intensities.…”

Acerca da métrica da percepção do espaço visual

“…A diferença está na ênfase, com distância egocêntrica sendo associada a um único e simples alvo, e distância em grande escala sendo associada com uma cena ou cenário inteiro. A questão central resume-se em entender no que se baseia o observador para perceber a diferença entre uma cena visual complexa e cópias da cena variando apenas em termos de escala como, por exemplo, configurando uma cena num espaço pictórico-fotográfico, num espaço virtual, ou em pequenas escalas construídas em aléias visuais em laboratórios, ou mesmo usando representações cognitivas de grandes espaços, como mapas (20,(36)(37) . Em particular, perguntamos que tipo de processamento perceptual e cognitivo está envolvido quando uma pessoa constata a imensidão no ambiente visível.…”