The paper investigates the issue of motivation of a subcategory of nouns called by Quirk et al. (1985: 303) and Huddleston & Pullum (2002: 345), respectively, unmarked plural nouns and uninflected plural-only nouns. These are nouns with untypical, from the perspective of the majority of English nouns, properties: their form, despite the plural designation, is singular. Adopting the general cognitive perspective on motivation in language (e.g. Lakoff 1987; Heine 1997; Radden, Panther 2004; Gibbs 2005; Panther, Radden 2011, etc.), the paper analyses whether such irregular properties of uninflected plural-only nouns can be motivated by one of the factors shaping visual experience – Gestalt principles of perception (e.g. Koffka 1936; Pomerantz 1981; Rock & Palmer S. 1990; Palmer S. 1999).