What phenomenon is sometimes cited as the likely mechanism by which the human brain perceived the indistinct Martian markings as straight lines?

Answer

pareidolia

Many features Lowell mapped were likely optical illusions created by the eye imposing order, such as straight lines, onto ambiguous or shadowy visual stimuli, a concept known as pareidolia.

What phenomenon is sometimes cited as the likely mechanism by which the human brain perceived the indistinct Martian markings as straight lines?
MarsastronomyobservationplanetCanal