It was, for years, an aphorism of adult contemporary and hot AC radio: "Adults know what they like. And they like what they know." It was the rallying cry for AC's move away from unproven music and, in some cases, from any current music at all. 

Through those years, you could count on most songs to follow a certain trajectory: edgy and young at the outset, then softened by time during the course of many years. Songs transitioned from top 40 to hot AC to AC because they no longer sounded so aggressive and/or because the audience that knew those songs aged into AC's target demos and brought those songs with them.

The recent adult success of top 40 and the strength of the mother/daughter coalition changed that. Billy Ocean's "Caribbean Queen (No More Love on the Run)" spent years on its journey from funky-at-the-time R&B crossover to the kind of song that you would only hear on mainstream AC. Fellow British R&B artist Taio Cruz's "Dynamite" was prompting adult sing-alongs at their kids' birthday parties within months of its release. 

For AC radio, that change has manifested itself in two ways.

First, it's no longer unusual to see an AC music test dominated by recent music. That would have been unthinkable in the past when only an inescapable hit of "I Will Always Love You" magnitude could count on quick traction. It's not the case across the board, but just seeing it happen at all is noteworthy.

Less obviously, it's no longer the case that being older means being more entrenched, and thus being bigger with adults. If songs were still taking hold the traditional way, Rihanna's "Umbrella" would be a bigger, safer adult record than "Only Girl (In the World)." That song would be bigger than "We Found Love." And "Diamonds" would be barely a blip on an adult listener's radar. That has changed, too.

For the first time in nearly 30 years, being new and exciting seems to mean something to moms, not just daughters. Or, expressed slightly differently, adults are becoming as fickle as their kids.

Some of that is just a function of hearing the songs more. The two top 40s in New York are around 108 weekly spins on powers. WKTU, which is more recurrent-driven, is in the 80s. The two hot ACs are in the 50s and 60s. Even the relatively gentle 24 spins a week that WLTW (Lite FM) gives its most-played song is about twice the prevailing wisdom for the format even five years ago. And that’s before you factor in all the ways in which adults hear songs beyond the radio. 

Top 40's Portable People Meter-driven tighter playlists mean that a relatively small handful of songs are aggressively taught to the audience in a short amount of time. For the first time, I now find myself unable to listen to many of the hits by the time they reach No. 1. I don't think that's typical of the rest of the audience, but it does reinforce that if adults like what they know, they know it a lot sooner.

Consider also the motivation for being a 38-year-old top 40 listener in the first place. If you are trying to keep pace with your kids, there's no benefit in being able to discuss the songs they liked six months or four years ago with them. So Usher's "Yeah," although it’s an entrenched adult record, is not necessarily better or safer than David Guetta & Usher's "Without You," not that there are any "cool parent" points available to you for that song either.

At the very least, this should have implications for how adult stations expose new music and the incubation time for records to make it from top 40 to hot AC to AC. It seems inevitable that we'll be hearing Rihanna's "Stay" and Justin Timberlake's "Suit & Tie" on mainstream AC for years to come. But this week, "Stay" has fewer than 100 AC spins. "Suit & Tie," perhaps because it would require editing out a rap, is barely registering at AC, even during a week when Timberlake is again the most prominent recording artist in the world. In all of this, there is likely a new way to be an adult radio station—and we're only beginning to figure it out.