Shouting to Be Heard in Advertising

Advertising competes for scarce consumer attention, so more profitable advertisers send more messages to break through the others' clutter. Multiple equilibria can arise: more messages in aggregate induce more "shouting to be heard", dissipating profit. Equilibria can involve a small range of loud shouters or large range of quiet whisperers. All advertisers prefer there to be less shouting. There is the largest diversity in message levels for a middling width of advertiser types: both a very wide or very narrow width have only one message per advertiser. The number of advertisers at each message level decreases with the level if the profit distribution is log-convex. Increasing the cost of sending messages can make all advertisers better off. A new technique is given for describing multiple equilibria, by determining how much examination is consistent with a given marginal advertiser.