A study presented at last week's MI6 game marketing conference indicates that games promoted by advance trailers sold better than those prefaced by playable demos, MTV Multiplayer reports.

The study, conducted by the Electronic Entertainment Design and Research Group, found that a majority of the highest selling titles on Xbox 360 and the PlayStation 3 were promoted by trailers alone. Games accompanied with trailers as well as playable demos sold significantly less on average.

The findings of the study are consistent across both platforms with one exception: games without trailers or demos available sold better on PlayStation 3 than Xbox 360, indicating that games on Microsoft's console are better off with some sort of promotional material on Xbox Live.

In light of the research, EEDAR heads Gregory Short and Geoffery Zatkin recommended that publishers make playable demos available only after release of a game.