In 1972, two psychologists split a bunch of guinea pigs, I mean students, into separate groups and played one of two audio tapes for them.
Both tapes contained the audio of a regular 30 min TV show. Squeezed in between were commercials for cigarettes and chewing gum and mouthwash and a headache pill.
At the end of the show, the students were asked a barrage of questions. Including a few about the commercials.
“Can you recall the type of product in the commercials? What about the brand name?”
The psychologists also followed up. Two days later. A week later.
“Can you still recall the type of product in the commercials? What about the brand name?”
The results:
One group of guinea pigs did as you might expect. They remembered the commercials pretty well right after the show… but less so two days later… and much less so a week later.
The second group was more interesting though, at least if you’re in the business of persuading.
This second group could remember the commercials better than group one right after the show… and the recall stayed at that same high level. Two days later. A week later. No drop off.
So what was the difference between the two groups?
Simple.
Group one heard the commercials in their original, unedited form.
Group two heard the same commercials, but with the last 5-6 seconds cut off.
You might recognize this as an example of the Ziegarnik effect.
In a nutshell, there’s a part of our brain that’s in charge of alertly waiting for the other shoe to drop. When the other shoe does drop, that part of the brain relaxes, and its alert attention slips away. But if the other shoe never drops…
By the way, the above study is not the only confirmation of the power of the Ziegarnik effect. That has been replicated in various settings in hundreds of different studies. The conclusion is clear:
“Waiting for the other shoe to drop” increases attention, improves memory, and raises active participation.
You might be wondering what I’m getting at. After all, direct response copywriters aren’t in the business of boosting recall, not two days later, not a week later.