Between 1983 and 1987 thousands of people in new york saw a ufo in the sky. it was estimated to be between 200 and 1000 feet long and had multicolored blinking lights. the ufo sighting turned out to be a hoax. rather than an actual ufo sighting, what viewers actually saw was a group of small planes with multicolored lights attached. the pilots would fly in formation that gave the impression of a ufo. they were even able to make it appear as though the ufo disappeared by turning off their lights simultaneously. the interpretation of the sighting was influenced by the viewers' perceptual

I believe the answer is: Perceptual set

Perceptual set is human tendency to focus on a certain data that we feel as 'important' and completely ignore the other existing data beside that.

In acquiring new information, perceptual set will make us have an extreme bias in analyzing the new information. We will only seek the data that confirm our pre-existing belief while ignoring other data that might challenge our view. (such as the believer of UFO that choose to ignore all contradicting evidence)

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.