For psychologists the ‘cocktail party effect’ or phenomenon is our impressive and under-appreciated ability to tune our attention to just one voice from a multitude.
At a party, when bored with our current conversational partner — and for the compulsive eavesdropper — allowing the aural attention to wander around the room is a handy trick.
Perhaps only the most recidivist eavesdroppers are aware how special the cocktail party effect is.
But even they might be surprised — and worried — by just how much we can miss in the voices we decide to tune out.
The cocktail party effect in psychology
The cocktail party effect or phenomenon — our ability to separate one conversation from another — is beautifully demonstrated in a classic study carried out by Colin Cherry (Cherry, 1953).
Cherry used the simple method of playing back two different messages at the same time to people, under a variety of conditions.
In doing so he discovered just how good we are at filtering what we hear, which is how we overcome the cocktail party problem.
To accomplish this task, Cherry reports, participants had to close their eyes and concentrate hard.
In the first set of experiments on the cocktail party effect he played back two different messages voiced by the same person through both ears of a pair of headphones and asked participants to ‘shadow’ one of the two messages they were hearing by speaking it out loud, and later by writing it down.
When doing this they could, with effort, and while hearing the clips over and over again, separate one of the messages from the other.
With the two voice presented together, as though the same person were standing in front of you saying two completely different things at the same time, this task appears to be very hard, but still possible.
Pushing participants further Cherry found he could confuse listeners, but only by having both messages consist entirely of nonsensical platitudes.
Only then were participants unable to pick apart one message from the other.
This is not a wholly satisfying demonstration of the cocktail party effect.
How the cocktail party effect works
The real surprise, though, came in the second set of experiments on the cocktail party effect or phenomenon.
For these Cherry fed one message to the left ear and one to the right ear — and once again both messages were voiced by the same speaker.
Suddenly participants found the task incredibly easy.
Indeed many were surprised how easily and accurately they could tune in to either one of the messages, and even shift their attention back and forth between the two.
No longer did they have to close their eyes and furrow their brows – this was much easier.
What participants were experiencing here seems much closer to most people’s experience of the cocktail party phenomenon.
At a party people are arrayed all around us and their conversations come from various different directions.
We seem to be able to use this information, which is key to the cocktail party effect, to reject all but the one in which we are interested.
Ignoring rejected speech
Although we are fantastically good at tuning in to one conversation over all the others, we seem to absorb very little information from the conversations we reject.
This is the flipside of the cocktail party effect and where it can get embarrassing.
Cherry’s experiments on the cocktail party effect revealed that people picked up surprisingly little information presented to the other, ‘rejected ear’, often failing to notice blatant changes to the unattended message.
When asked afterwards, participants:
- could not identify a single phrase from the speech presented to the rejected ear.
- weren’t sure the language in the rejected ear was even English.
- failed to notice when it changed to German.
- mostly didn’t notice when the speech to the rejected ear was being played backwards (though some did report that it sounded a bit strange).
Across all the different conditions in these cocktail party effect studies, there were only two aspects of the speech to the rejected ear the participants could reliably identify.
The first was that it was speech compared to a tone, the second was when the speaker suddenly changed from male to female.
Missed your own name
This research on the cocktail party effect doesn’t bode at all well for people with a habit of tuning out of conversations when they lose interest (you know who you are!).
If you really are listening to someone else it’s likely you won’t hear a word of what’s being said to you directly.
One study has found that two-thirds of people don’t even notice when their own name is slipped into the unattended speech, while those who do notice are likely to be of the extremely distractable variety (Conway et al., 2001).
That demonstrates the power of the cocktail party effect.