Comment by est31

Humans also constantly make mistakes that are due to proximity in their internal representation. "Could of"/"Should of" comes to mind: the letters "of" have a large edit distance from "'ve", but their pronunciation is very similar.

Especially native speakers are prone to the mistake as they grew up learning english as illiterate children, from sounds only, compared to how most people learning english as second language do it, together with the textual representation.

Psychologists use this trick as well to figure out internal representations, for example the rorschach test.

And probably, if you asked random people in the street how many p's there is in "Philippines", you'd also get lots of wrong answers. It's tricky due to the double p and the initial p being part of an f sound. The demonym uses "F" as the first letter, and in many languages, say Spanish, also the country name uses an F.