HOW DOES EXPECTATION CHANGE PERCEPTION? : A SIMULATION MODEL OF EXPECTATION EFFECT
Editor: Christian Weber, Stephan Husung, Gaetano Cascini, Marco CantaMESsa, Dorian Marjanovic, Monica Bordegoni
Author: Yanagisawa, Hideyoshi; Mikami, Natsu
Institution: University of Tokyo, Japan
Section: User-Centred Design, Design of Socio-Technical Systems
Prior expectation affects posterior perception of physical variables, such as weight of a product. This psychological effect is called expectation effect. Two different patterns of expectation effect, contrast and assimilation, were observed. In this paper, we propose a simulation model of the expectation effect that explains the conditions of contrast and assimilation. We assume that perceived variable is estimated using a Bayes’ inference of prior prediction and likelihood based on sensory stimuli. We formalize the expectation effect as a function of three factors: expectation error, prediction uncertainty, and external noise. We conducted computer simulations with the model and obtained a hypothesis of the conditions of assimilation and contrast. To validate the hypothesis, we conducted an experiment with participants using the size-weight illusion as a case of the expectation effect. Both the results of the simulation and the experiment revealed that 1) the pattern of expectation effect shifted from assimilation to contrast as the prediction error increased, 2) uncertainty decreased the extent of the expectation effect, 3) and external noise increased the assimilation.