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Five main findings provide evidence for the phonological loop:

1. The effect of phonological similarity:
   Lists of words that sound similar are more difficult to remember than words that sound different. Semantic similarity (similarity of meaning) has comparatively little effect, supporting the assumption that verbal information is coded largely phonologically in working memory.
2. The effect of articulatory suppression:
   Memory for verbal material is impaired when people are asked to say something irrelevant aloud. This is assumed to block the articulatory rehearsal process, thereby leaving memory traces in the phonological loop to decay.
3. Transfer of information between codes:
   With visually presented items, adults usually name and sub-vocally rehearse them, so the information is transferred from a visual to an auditory code. Articulatory suppression prevents this transfer, and in that case the above mentioned effect of phonological similarity is erased for visually presented items.
4. Neuropsychological evidence:
   A defective phonological store explains the behaviour of patients with a specific deficit in phonological short-term memory. Aphasic patients with dyspraxia are unable to set up the speech motor codes necessary for articulation, caused by a deficiency of the articulatory rehearsal process.
5. On the other hand, patients with dysarthia, whose speech problems are secondary, show a normal capacity for rehearsal. This suggests that it is the subvocal rehearsing that is crucial.