Does self-directed speech help or hurt a blind subject's auditory recognition? Recently, it was found that self-directed speech was helpful to sighted subjects engaging in a visual search task:


  Participants searched for common objects, while being sometimes [sic] asked to speak the target’s name aloud. Speaking facilitated search, particularly when there was a strong association between the name and the visual target. As the discrepancy between the name and the target increased, speaking began to impair performance. Together, these results speak to the power of words to modulate ongoing visual processing.


So, if the subject were to be looking for a chair in a picture, saying the word "chair" aloud would lead to a more effective search.  Since the two modalities (vision and hearing) are separate, one set of information can compliment the other set and "constructively interferes," if you will, in the scenario above.  

In trying to establish whether a similar "constructive interference" would occur in the auditory domain, so I'm wondering whether an experiment wherein a subject who is blind (since birth) repeating a word to themselves would show an difference in that subject's ability to discriminate muffled or otherwise disguised words that they were asked to listen to and identify as part of a task.  

Would the degree to which repeating a word was helpful or harmful still depend on the similarity between the word spoken out loud and the word to be discriminated?  Or would there be a "destructive interference" effect under any circumstances, due to the same modality of hearing being used for the both discrimination of the information and the perception of the self-directed speech?


  Lupyan, G., Swingley, D. (2011).  Self-directed speech affects visual search performance.  The Quarterly Journal of Experimental Psychology, iFirst, 1-18.  DOI
It seems apparent that generating and hearing self-directed speech during discriminatory listening would inhibit said discrimination. This is because auditory processing of self-directed speech and audio processing in discriminatory listening would have to compete for resources in decoding auditory information, leading to poorer decoding of the already low-quality muffled audio. 

If on the other hand the self-directed speech is performed only in-between the trials of discriminatory listening, then this competition for auditory-decoding resources no longer occurs.  In this case, I expect that the self-directed speech would effectively prime cognitive resources that are involved in discriminating the source of the muffled speech. This, then, would result in improved discriminatory performance. At least that would be my initial hypothesis.