When the Dorsal Stream is Shallow


Dorsal Stream ShallowWe’re not referring to the type of stream you fish in.  Perhaps a bit closer to the concepts behind video streaming.

Streaming Video

Streams of VisionHere’s a nice depiction of the two streams hypothesis of the visual system from a talented artist on the autistic spectrum, with the cat’s eyes representing the visual cortex.  In fact, the way this autistic artist operates through picture thinking is represented very well, as you can see here: http://autisticandawesome.wordpress.com/2012/08/05/the-visual-system-part-2/

Look at the painful description this person gives of reading text: “I hate learning that way, from big blocks of text with few pictures, the text separate from the pictures that the text describes. I hate textbooks. I hate their text, and I hate their pictures. Their text is long and boring, and their pictures are ugly and cluttered. It is hard for me to learn anything that I don’t already know from the text and pictures of a textbook.”

visual-impairment-in-children-due-to-damage-to-the-brain-clinics-in-developmental-medicineFollow this stream of consciousness back to the textbook I quoted extensively from in the previous post – and you’ll get a clue that our autistic artist has difficulty integrating the dorsal and ventral streams.  More specifically, our artist’s self-description sounds like Dorsal Stream Dysfunction (DSD).  Chapter 7 by Dutton et al explains why reading may be difficult due to crowding of the text, or complexity of the visual scene.  Hence our artist’s whimsical and liberally spaced renditions.  Dutton et al note that plus spectacle lenses which would normally not be prescribed based on acuity needs can help DSD patients with problems accessing text on the basis of crowding or clutter.

television07There’s a question that parents ask that’s been around as long as the TV itself: Why does my child insist on getting so close to the television?  In some instances it’s due to uncompensated refractive issues, but in some cases it is due to a shallow dorsal stream.  As Dutton et al note regarding DSD: “Seeing objects in the distance is difficult, as the further away things are, the more visual information there is in the scene.  For this reason, children with dorsal stream dysfunction like to get very close to the television, presumably so that they can give visuial and auditory attention to the individual elements of a moving scene.”

You can read a great overview of Dorsal Stream Dysfunction and the DSD tree at this website:

http://www.ssc.education.ed.ac.uk/courses/vi&multi/vdec082iii.html

DSD Tree

 

2 thoughts on “When the Dorsal Stream is Shallow

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s