The brain is a seemingly endless library, whose shelves house our most precious memories. To allow new memories to form, old information is sometimes pushed out of the brain.

    Previous studies have shown that learning new information can lead to {#blank#}1{#/blank#}. But in a new study, researchers showed for the first time how this effect {#blank#}2{#/blank#} in the brain.

    In daily life, forgetting actually has clear {#blank#}3{#/blank#}. Imagine, for instance, that you lost your bank card. The new card you receive will come with a new personal identification number (PIN). Each time you remember the new PIN, you gradually forget the old one. This process improves access to {#blank#}4{#/blank#} information, without old memories interfering.

    And most of us may sometimes feel {#blank#}5{#/blank#} when old memories interfere with new, relevant memories. Consider trying to remember where you parked your car in the same car park you were at a week earlier. This type of memory is particularly interfering.

    When we get new information, the brain automatically tries to combine it with existing information by {#blank#}6{#/blank#} associations. And when we retrieve（检索）information, both the desired and {#blank#}7{#/blank#} but irrelevant information is recalled.

    The majority of previous research has focused on how we learn and remember new information. But current studies are beginning to put greater {#blank#}8{#/blank#} on the conditions under which we forget, as its importance begins to be more appreciated.

    A very small number of people are able to remember almost every detail of their life. Though it may sound like an advantage to many, people with this rare condition often find their {#blank#}9{#/blank#} ability troublesome. In a sense, normal forgetting may help to ensure our brain doesn't become too full.