Tie strength and media use in friendships across the course of a year: Testing media multiplexity theory's third proposition

Although central to media multiplexity theory's logic, the proposition that tie strength and media multiplexity mutually cause each other has received limited empirical test. This study evaluated this proposition via survey data collected from friends in Spring 2020 and Spring 2021, examining their friendship across the first year of the COVID-19 pandemic. When examining retrospective reports of the relationship pre-pandemic, results supported the claim that media multiplexity predicts tie strength; in contrast, longitudinal results between Spring 2020 and Spring 2021 supported the claim that tie strength predicts media multiplexity. These findings may indicate a need for clearer boundary conditions for the theory, as well as more thorough consideration of the explanatory mechanisms that underlie the link between multiplexity and tie strength.