There's an interesting phenomena where the brains of people with arachnophobia will enlarge the perceived size of spiders. People with an irrational fear of spiders literally perceive spiders to be bigger than other people.

The sample size wasn't exactly huge (https://www.sciencedirect.com/science/article/pii/S088761851...) but the science seems to resonate with other research in the field.

All of this is to say that it's possible that someone may perceive a spider to be much bigger than it really is, through no fault of their own.

That's really curious, do you know where else this is the case? Other phobias?

I'm no doctor, nor am I a psychologist, so I can't easily pick out good sources for this topic. All I remember is this particular story hitting the news and really resonating with me (mostly because I have an irrational reaction to spiders myself, though "fear" may not be the right term).

There are 83 works on Google Scholar citing the paper I linked above: https://scholar.google.com/scholar?cites=1525421616690417423...

I'm not qualified to judge these papers nor their journals, but some of them may serve as a jumping off point for your own research if you're interested! Some papers seem to revolve around general state-of-mind biases ("Human safety and risk management"), while others focus on more concrete links such as biases in perception of "interpersonal distance".