While popcorn has been synonymous with the cinema for decades, many people finish their snacks well before films have even started. With fifteen-twenty minutes worth of ads commonplace, it can be extremely tempting to finish your snacks before the opening titles appear on screen. However, a Journal of Consumer Psychology study entitled 'Popcorn in the cinema: Oral interference sabotages advertising effects' explains how one major source of revenue for cinema operators might actually cancel another one out.

Authors Sascha Topolinski, Sandy Lindner and Anna Freudenberg ran an experiment where they showed three different groups a series of advertisements. They allowed one group to eat popcorn during the ads, another to chew gum and a final set of control participants to consume a single cube of sugar before the ads (ensuring their sweet tooth was satisfied).

The researchers then examined the different groups' consumer activities the following week. The control group were found to have spent more money and had more pronounced "psychological responses" to the advertisements than those who had been 'distracted' by the snacks. The study concludes "advertising might be futile under ecological situations involving oral interference, such as snacking or talking, which ironically is often the case".

The teams goes as far as suggesting "in the future, when promoting a novel brand, advertising clients might consider trying to prevent candy being sold before the main movie". It's unlikely the cinemas themselves would agree to such an arrangement: while pre-film advertisements can serve as a valuable source of additional income, the high mark-up on cheaply produced snacks such as popcorn allows the theaters to earn a significantly higher profit than they do on the film tickets themselves.