I am now finding some research to provide the argument below "Comparing to Realistic icon, Simple icon can speed up user’s recognition of the icon "

I am now finding some research to proof the argument below

"Comparing to Realistic icon, Simple icon can speed up user's recognition of the icon "

i found some argument with same point of view in NN/ Group article- Icon Usability

Keep the design simple and schematic. Reduce the amount of graphic details by focusing on the basic characteristics of the object rather than creating a highly realistic image in order to speed up recognition. (Intricate details are difficult to distinguish at smaller sizes.)

However, i can't find any strong research evidence behind this article, is there any strong research evidence could proof this argument?