Chapter 5~ You Know My Name, Look Up the Number

   Daniel J. Levitin poses the question of why can music trigger memories in humans that seem to be lost. Memories are encoded in groups of neurons and with the right cue, it will cause the memory to be retrieved. The more a memory is accessed, the easier it is to retrieve that memory later on. A song can be a cue that accesses memories, thus making the music move the person listening in a certain way because humans' memory systems are closely linked to the humans' emotional systems. Tune recognition involves neural computations interacting with memory. The brain extracts features that remain constant from each listening of a particular piece of music to perform these computations. When trying to remember a memory, the brain undergoes a process similar to perceptual completion in which it fills in the missing information. For example, if someone is recounting a dream, they will not remember each detail, so they begin fabricating information to finish the story. This activity takes place in the left side of the brain. There are two views on how humans preserve memories. The constructivist view is that the function of a memory is to ignore irrelevant details, while preserve the gist. The record-keeping view is that a memory is like a video camera that records each and every detail accurately.  There is evidence that supports both views, but according to Daniel J. Levitin neither one is correct and there is no theory that is correct at the moment.

   Humans have categories for all things whether they be living or inanimate. Music is categorized into different genres based on the musical structure of a piece. Some songs have elements of different genres, but they are still categorized under a certain genre. For example, a song might have elements of heavy metal like guitar riffs, but it is categorized as pop because the song resembles a pop song overall. Songs are categorized into genres based on the prototypical songs for musical categories. Daniel J. Levitin gives the example of choosing colors. When someone asks to choose the color red out of various shades of the color, one would choose the best example of red. There are three scenarios that organisms must deal with that are based on categorization. The first is that objects that appear similar are different. Objects may create similar or identical patterns of stimulation on humans' eardrums, retinas, taste buds, or touch sensors that cause humans to think the objects are the same. For example, an apple on a tree is different than an apple in someone's hand, but the two are different. The second scenario is that objects are identical though they might appear different. Looking at an object from different viewpoints might make the object appear as two different objects. The human brain has to extract information from the different viewpoints to create a unified representation of the object. The third scenario is that though objects are different, they are from the same category. For example, a red apple is different from a green apple, but both are apples. These three scenarios use the sensory surfaces to gather information for analysis to which adaptive behavior is dependent on. The concept of categorization allows listeners, composers, and performers to know the elements of a genre that a song of that genre should have. This gives the human brain expectations of what should happen in the music. When the music deviates from the expectation, it moves people and causes them to feel different emotions.

   How do songs get stuck in people's heads? Neural mechanisms that underlie perception of music and memory for music called ear worms. The neural circuits that represent a song get stuck in "playback mode" or plays back over and over again. Small pieces of songs get stuck rather than whole songs. Simple songs and commercial jingles are more likely to get stuck rather than complex songs. The fragment of a song that gets stuck is usually fifteen to thirty seconds. Songs that suit a person musical preference are also more likely to get stuck in their head. People with obsessive-compulsive disorder are often troubled with ear worms and have to take medication. When people sing the songs that get stuck in their heads, they usually sing the songs with accurate pitch and tempo, according to Daniel J. Levitin's studies. Songs have an overall sound with specific pitches and rhythms. Human memory remembers the overall soundscape of a song that allows humans to sing the song with accurate pitch and tempo.