An imageless choice is one in which the paraphenalia (“tools” [note quotes, which indicate a figure of speech in this case]) involved in choosing are not manifest.  This means, for example, that, in effect, a blank mind can communicate both plans of choosing and options.  In street language:

It is possible for a blank mind to communicate both plans of choosing and options.

In fifth grade language:

A person can consciously choose even though their mind is blank.