In fact, it has been shown that older and younger adults' performances were equal when none of them were allowed to subvocally
rehearse the digits (Gerhand, 1994; cited in Phillips & Hamilton, 2001).
In this work, a sample of 9 adults performed a working-memory task (in which they had to remember 1 or 6 visually presented letters) and a motor rehearsal task (they read subvocally
1 or 6 letters).
The authors posited the slow rate provided students enough time to subvocally
read the words before or after the word was presented, but the fast rate condition did not allow for opportunities to respond.
That is, he was encouraged to pronounce the word to be spelled either vocally or subvocally
, to segment it into phonemes, and to mark each phoneme with the corresponding letter.
There were very few omissions and no overt evidence of painstaking attempts to sound the items out, although a couple of the less-skilled readers were very slow and may have been doing this subvocally
In contrast, children of average and above-average IQ showed virtually no performance gain after instructions to name the stimuli aloud, presumably because they were already naming them spontaneously, but subvocally
, prior to the instruction (34; see also 52, 55, 56, 67, 78, 93).