I think you nailed it in your previous post. It's called motivated reasoning, which Harrison addresses at length.

Harry Marks wrote: The difference is surely going to involve both the difficulty of "looking more closely" as we would for a tiger, and some process which makes us **want** to continue seeing Jesus in the grilled cheese sandwich, or whatever it is.

So when we think a stick on the ground is a snake and jump back, we immediately see our error and laugh it off. I've done this numerous times.

But seeing Jesus in a grilled cheese sandwich is motivated from the start. It's pretty obvious I think why people want to believe in Jesus and look for him in the real world. The face on Mars is a similar situation. We see a pattern—a face—and should immediately realize it's just a random geographical feature. But a few people love the idea of intelligent life in the cosmos and see the face as evidence of a long-lost civilization or whatever.