Are you particularly good in a blind test? Are you one of those people who can recognize a song from hearing just the first few notes? Researchers decided to precisely quantify this ability. Using electroencephalography and pupillometry, the scientists wanted to understand how quickly the brain could identify excerpts from a familiar and well-liked song from a selection of unknown excerpts, as well as identify the “neural signatures” of this recognition.

As a preamble to their research, the scientists from the Ear Institute (University College London) point out that research has shown that the concept of musical familiarity is based largely on traces of long-term memory (mental auditory imagery), and that it is also linked to autobiographical memory (certain songs illicit emotions linked to positive memories).

In order to measure how fast the brain can discriminate a familiar song from an unknown song, the research team created two independent groups: a main group, consisting of 10 people (average age = 23.56; 5 women) and a control group of 12 people (average age 23.08; 9 women). Each member of the first group created a list of five songs that they listened to often, associated with positive emotions, and to which they attributed a personal connection. One song was then chosen for each participant and associated with a control song (an unfamiliar song, but with a similar melody, instruments, and voice). In the end, 10 dyads were created (one per person), each containing a familiar song and an unknown song. The songs chosen included Chuck Berry (You never can tell), Muse (Dead inside) and Barbra Streisand (The way we were). Note that the musical correspondences were checked with the control group (consisting of foreign students who did not know all the songs used in the protocol). Each song was divided into 750 millisecond extracts, of which 100 were randomly selected.

These very short musical samples were then used in two tasks: a passive listening and an active categorization exercise. In the first exercise, the participants were asked to carefully listen to the excerpts from each dyad randomly, while their brain activity was recorded using the EEG, and their pupil diameter was measured using a pupillometer. While members of the control group listened to the 10 dyads, those in the experimental group only listened to those containing their familiar song. For the active categorization task, participants had to indicate whether the extracts they were hearing came from the same song or not (20 categorizations).

100 milliseconds! This was the shortest amount of time it took participants’ brains to recognize a familiar song. In this study, pupillometry indicates average recognition times ranged from 100 ms to 300 ms (rapid pupil dilation is likely caused by increased excitation associated with the familiar piece of music). EEG data showed a differentiation between familiar and unfamiliar songs from 350 ms. In contrast, the control group showed none of these signs of recognition (ocular or cerebral). According to study co-author Maria Chait: “Our results demonstrate that recognition of familiar music happens remarkably quickly […] 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.”

Despite significant limitations (including cohort size), the authors believe that the results of this study shed light on how our brain recognizes familiar pieces of music, something which may be useful, “to break through to dementia patients for whom memory of music appears well preserved despite an otherwise systemic failure of memory systems.”