That being said, we should also note the emotional connection we have with music. As humans, we have the tendency to form associations in our memory with different songs. As a result of these associations, songs becomes stimuli that have the ability set off internal triggers within ourselves, whether it be a sense of joy from the memory of a night out with friends after hearing a song played that night or a sense of depression after listening to a song that reminded you of a deceased relative.
At times we want to relive those moments. We dig up these events from our memory through associated songs, providing a sense of nostalgia and experiencing those emotions again. This is where the familiarity heuristic comes into play.
Understood to be a cognitive "rule of thumb", the familiarity heuristic is our tendency to form decisions favoring what we know (the "familiar") instead of what we don't. We understand what songs impact our moods and in what ways. There are songs that cheers us up, chill us out, and so on. Being that we have a massive selection of music to choose from on music streaming platforms, we can feel overwhelmed with the vast catalogue available. Unless you're specifically searching for new music to listen to, as music consumers we rely on the familiarity heuristic to help us decide what we end up listening to.
When it comes to our consumption, we rely on those associated emotions to help us make that decision. Once we make a song selection, Spotify's recommended-songs feature kicks in and plays a suggested track based on the original one. In using context- and content-based data to make their suggestion, Spotify is pretty accurate in pinning down your mood and, as a result, will keep the songs aligned with your mood.
Spotify clearly has a deep understanding of not only the psychology of their consumers and the link between music and emotion (which could be one of the many reasons why Mood Playlists were made available on the Spotify platform), but also an awareness of our mobile phone usage. With users spending increasingly more time within the Spotify app, Spotify's doing something right in terms of keeping consumers engaged within the app. Instead of potentially irritating people with push notifications from another mobile phone app, Spotify's usage of machine learning is undoubtedly a strategic way to implement nudge theory on a media platform like their own.