How do Gregor Samsa’s parents and sister come to the conclusion that he is the arthropod?

I believe that if I were to see a giant bug emerge from my brother’s room, I would assume that it had invaded his room from the outside, and I would worry that it had hurt my brother in some way. This seems to me a much more natural conclusion than the story’s correct one, and yet the Samsas never look around for any trace of the possibly injured or devoured Gregor (e.g. shredded clothes, blood)…because they somehow know that he has transformed into the creature.

I believe that if I were to see a giant bug in my house, I would immediately focus all efforts on exterminating it, enlisting the help of neighbors or professionals. Yet the Samsas shepherd the bug into his room, keep him secret as far as possible, and start feeding him, because they somehow recognize the bug as him.

He is unable to communicate to them in any understandable way. For them to come to the conclusion of Gregor’s metamorphosis into a many-legged vermin violates all common sense and all reason, which means that the family’s unanimous conclusion is the result of that instantaneous, emotionally tinged, and seemingly infallible faculty—recognition.

The concept of recognition is a fascinating one, especially when you consider that the human brain has a processing area set aside for recognizing faces. In youth I had a mild phobia of developing prosopagnosia (the inability to recognize familiar faces) even before I knew that this was a real neurological condition: the ability to recognize is so powerful and so mysterious that it captured my imagination.

In Kafka’s story, the recognition functions like religious faith (another fascinating concept?): the Kierkegaardian leap is taken, bolstered by its collective nature, but at the end of the story the irrational belief falls away. It is only under duress, after months of belief that have borne no fruit and only misery, that the family even entertains the thoughts “I don’t want to call this monster my brother…I can’t endure it any more” and “How can that be Gregor?”—but once they decide to reverse their recognition, it is enough to kill Gregor without their touching him.