On more pointed testing Sanders and I, along with the National Hospital psychologist Elizabeth K. Warrington, discovered to our amazement that Daniel's "blind" field was not blind at all in the usual sense. . . . When objects were placed in his blind field, he made virtually no errors locating them, though he could not tell us what they were. . . . "I couldn't see anything, not a darn thing," Daniel told us. All he would allow was a "feeling" about an object in some, but not all, [of] the tests. We named the extraordinary phenomenon blindsight.
Source: wiktionary