When I was a quiet and passive four- or five-year-old child, my family would frequently drive the 30 miles to Duluth for my brother to see an eye doctor. We would go to this mysterious building called the Medical Arts Building. But before we could go down the hall to the doctor's office, the five of us in our family, and sometimes a few strangers, would enter this small room. The door would close, the room would shake, the door would open, and then we were allowed to walk down the hall to see the doctor. It seemed clear to me why we did this: I knew what the word "medical" meant, and I knew there were these bad things called germs which had something to do with things medical. So I assumed we went into the room to have the germs shaken off of us. I did not know why we did it on the way out. Did we pick up more germs in the doctor's office?
Now I submit that this was a reasonable inference for a five-year-old who had never heard of elevators. The result of this on my life is threefold: 1) I still think of travel in 30 mile units. 2) When I hear the world "elevator" I picture the Medical Arts Building. 3) I am no longer quiet and passive, to the regret of all who know me, and am willing to ask questions, except for directions.
When I was about twelve, without explaining why, my father told me to put the garden hose in the back of the pickup. He walked off do something else. After I had done the task, he came back and told me that he had changed his mind; that I should mow the lawn instead. Not knowing what "instead" referred to, I got out the mower. He drove up the rough track to our upper meadow, where we also had a potato field. I was wondering why he wanted the garden hose up there, where there was no source of water. Then I saw the problem. In a few minutes the pickup came bouncing down the track, much faster than it should. My father was a man of quick and hot temper. He got out of the pickup and snapped at me that I should pay attention. He had told me clearly to put the garden hoes in the pickup and I had put the garden hose in the pickup instead. Then it dawned on him. He stopped, stared at me for a bit. Then he went and got his hoe and drove slowly back up the track.
It was as close as he ever came to apologizing to me until I was an adult.
When my granddaughter was three, she was afraid of my mother, who was missing a leg and confined to a wheelchair in a nursing home in Sioux Falls. One day her parents were driving to South Dakota to visit her other grandparents, who live near Sioux Falls. They told Lily that they were also going to go see great-grandma. Lily promised she was not going to be afraid of her this time. When they arrived at the other grandparents, they found a note on the door to meet them at a restaurant and that great-aunt Edith was there too. When they told Lily that she was going to meet great-aunt Edith, Lily asked, "Is she all there?"
It seemed a reasonable guess apparently that "great" meant you are missing a body part.
Have you ever been tripped up by a faulty inference?
Edited to add: