something that a person can see, smell, touch, taste, or hear

an electric shock

a memory

a message from the brain that produces hormones

Your brain produces a hormone that tells you to run when you see a bear.

Marcel Proust ate a madeleine and recalled a large portion of his childhood.

You automatically move your foot away from a sharp object after stepping on that object.

You can remember what your mother's face looks like.

writing a novel and remembering things from a long time ago

moving away from something that causes you pain automatically

feeling scared when you see something dangerous

a former soldier hearing a plane overhead and automatically producing adrenaline