It only takes your brain a fraction of a second to recognize a familiar song, new research reports.

Researchers at the UCL Ear Institute, perhaps taking inspiration from game shows such as ‘Name That Tune’, wanted to find out just how fast our brains can respond to familiar music. It’s pretty fast.

As fast as sound

The team worked with an experimental group consisting of five men and five women. Each of them had provided the team with a list of five songs that were familiar to them. The team then picked one of these songs, matched it to a tune that was similar in terms of tempo, melody, harmony, vocals, and instrumentation (but which was unfamiliar to the participant).

Each participant was then asked to listen to 100 snippets, each lasting less than a second, of the familiar and the unfamiliar song in random order. The researchers monitored each participant using electro-encephalography (EEG) imaging, which records electrical activity in the brain, and pupillometry, a technique that measures pupil diameter as a measure of arousal.

The team explains that familiarity is a multifaceted concept and that, for their study, they instructed participants explicitly to select songs that evoke positive feelings and memories. This means that part of what the team studied here is recognisability, and partly emotional engagement and affect.

It took participants’ brains about 100 milliseconds (0.1 seconds) to recognize a familiar song after first hearing it; the average recognition time was between 100ms and 300ms, the team explains. Recognition of a song was judged based on rapid pupil dilation (likely caused by increased arousal associated with the familiar sound) and cortical activation related to memory retrieval.

A control group consisting of international students — who were unfamiliar with all the songs — used in the trial didn’t show either of these signs of recognition.

“Our results demonstrate that recognition of familiar music happens remarkably quickly,” says Professor Maria Chait, senior author of the study.

“These findings point to very fast temporal circuitry and are consistent with the deep hold that highly familiar pieces of music have on our memory.”

Most of us see music as art, entertainment, a hobby, and not much beyond that. However, the team says that understanding how our brains recognize familiar tunes can help us devise therapeutic interventions for patients that may otherwise be beyond our help. For example, dementia patients seem to have well-preserved memories of music, even if their memory is otherwise faulty — understanding what makes music different in this case can help us pinpoint the causes of dementia.

Some limitations of the study include this bleed-through between recognizability and emotional engagement, manual selection of the songs due to technological limitations, and the use of a single ‘familiar’ song per subject; this latter one likely limited the demands on the memory processes studied, they explain.

The paper “Rapid Brain Responses to Familiar vs. Unfamiliar Music – an EEG and Pupillometry study” has been published in the journal Scientific Reports.