Both...it depends
From the book "ABC of Common Grammatical Errors" by Nigel D. Turton
Case #1
None of the food were fit for human consumption. [incorrect]
None of the food was fit for human consumption. [correct]
Explanation: When
none of is followed by an uncountable noun ("food"), the verb is singular.
Case #2
None of these murders have been solved yet. [depends]
None of these murders has been solved yet. [correct]
Explanation: When
none of is followed by a plural count noun ("murders"), the verb may be either singular or plural. When we mean "not a single one", the verb is singular: "None of these essays is worthy of a distinction."
When we mean "all...not", the verb is plural: "None of the shops are open today."
In formal styles, careful users generally prefer a single verb.
--------------------------------------------------------------------
My take? Let's look at the original example questioned by
commonpeople:
commonpeople said:
"None of the images are believed to be real at this time"
Shouldn't that be "None of the images is believed to be real at this time"?
I believe, based on the reference and explanation I quoted, that he/she is correct here. "None of the images" more likely means "not one of the images" because we would consider each image as a separate case (i.e. a submission, attachment, or link) rather than consider the whole collection of images. (See the "essay" example above.)
I suppose in the end, it depends on your interpretation and what you personally feel comfortable with. In my last 10 years teaching English at the university level, I've realized how pointless these arguments can sometimes be. Typically, my default response to questions of this sort is, "It depends." That keeps me out of trouble.
I hope this helps.
-Squire
<edit> The post above by
joe adk is excellent. I highly recommend that great little book:
The Elements of Style.