The part-whole proportion illusion in printing

Abstract

A survey of 400 books revealed that the median book devoted 52.8% of the page to print. The most frequent estimate given by 928 college students was 75%. This illusion was investigated experimentally by using a series of cards of three sizes in which the margins were white and the center merely black, or vice versa, with no printed text at all. Three groups of 100 college students each estimated the proportion of the cards occupied by the centers. These groups also over-estimated the proportion of the center to the whole by about 18%. (PsycInfo Database Record (c) 2025 APA, all rights reserved)