Caveat lector: This post presents more questions than it does answers. It may also be appropriate to ignore all this theorizing and file this separately under 'Kids say the darnedest things.'
A colleague asked me to review one of her cases because the child was presenting with some peculiarities. This four year old child's main difficulties are that he is 'overly sensitive,' as well as having some functional problems with attending skills and fine motor coordination. The parent perceives the child as 'different.' This could be underscored by the child's recent statement of "Do you hear my eyes blinking?" and reporting that watching his father's eyes blink sounded differently than the sound of his own eyes blinking.
I am aware of the concept of synesthesia - and believe that most of what I have read is more related to color perception of words and other odd cross modal perceptions. I had not heard of auditory perceptions based on visual flicker but came across some work by Melissa Saenz and Christof Koch. They have an online test for this phenomenon at http://www.klab.caltech.edu/~saenz/hearing-motion.html
Now I don't know if this child has visual-auditory synesthesia but I thought that the child's statements were interesting. It might be pertinent to this child's development because the process of attending involves 'learning' which environmental stimuli are most pertinent and salient. In other words, we 'learn' that the teacher's voice is to be given more sensory 'weight' than the whirring of the ventilation fans in the classroom. So, if synesthesia is an actual neurological phenomenon - do synesthetes have any greater risk of developmental attentional difficulties? Presumably, they would have 'extra' cross modal information to sift through while determining which sensory input was most important.
In an interesting online interview, Dr. Simon Baron-Cohen talks about linkages between autism and synesthesia. All of this relates to his other discussions relating to central coherence and Theory of Mind - the idea here being that someone who can't choose salient stimuli for attending obviously can't form correct perceptions, or form contextually appropriate perceptions.
As autistic spectrum disorders occur on a spectrum of severity, could my colleague be working with a child who has mild synesthesia that is causing sensory misperception and confusion, which in turn is causing some developmental attending difficulty?
Or is it just cute that he can hear people blinking?
I experience the very same type of synesthesia as this child.
My childhood was full of teachers recognizing me as "different" yet gifted but unable to pay attention. I was tested for ADD and I had no deficit, but they failed to discover my synesthesia. Had Dr. Saenz's research been available at the time, things might have been different.