Someone once said to me, the person's memory, in fact, is the most easy to forget the sad things, let us quietly back suddenly back, remember, is mostly happy memories.

曾有人对我说过，人的记忆中，其实对伤心难过的事情是最容易遗忘的，让我们悄然回蓦往事，记住的，大多是些开心快乐的往事。

youdao

When something interrupts the memory-storage process–like a hard knock to the head–newly formed memories aren't stored for the long run and you can't remember things that just happened.

当记忆储存的过程被打断——就像头被狠狠的敲击。新形成的记忆就不会持续很久，所以就不能记住刚刚发生的事情。这叫作顺行性遗忘症。

youdao

The study found that the recounted memories are almost always positive, that people remember particular episodes very vividly - sounds, smells and sights of the memory were often recounted.

BBC: Beatles' tunes aid memory recall