Hacker News Reader

Comment by DoctorOetker | Hacker News Reader

Is there a difference between vertically and horizontally written languages, given that the left field of view of each eye are processed in the same half of the brain, and the right half of FOV processed in the other half of the brain?

For horizontal languages like say english, the most relevant words are to the left and right of the current word, so left context and right context are initially in different halves of the brain.

For vertical languages relevant symbols are above and below the currently observed symbol, so if there is overlap of right and left FOV then both halves have the full context, if no overlap then both halves get the full context but only partially each symbol...

View on HN

Does this matter in practice? We have binocular vision--when I read, I focus on a word with both eyes. The occasions where I'm reading with just one eye or another are fairly rare.

The structural and functional division isn't between the eyes; it is present in both eyes.

https://en.wikipedia.org/wiki/Divided_visual_field_paradigm

So if we are reading horizontally, the not-yet seen text is in a portion of the field of vision of both eyes that is routed to one brain hemisphere; the text already scanned is in the opposite field of vision going to the other hemisphere.

The field of vision split is right down the middle of each eye. One side of the brain gets the two left-halves, the other the right. FWIW. Oliver Sacks' The Man Who Mistook His Wife For A Hat has a chapter on hemispatial neglect which is an interesting read.

(The entire book is fascinating.)

https://en.wikipedia.org/wiki/The_Man_Who_Mistook_His_Wife_f...

Try as I might, I can't find details about the field of vision split. Like how perfectly vertical and straight is the division? What is the microscopic structure like: how crisp is the line at the cellular level? Is there some messiness at the boundary with regard to which hemisphere the cones and rods are routed to? Does the division run precisely through the middle of the fovea?

This paper should help. :)

https://www.ncbi.nlm.nih.gov/books/NBK10944/

Empirically, when running tests where you wanted a clear hemisphere separation, we always used between one and two degrees off the centerline axis. This was undergrad cog sci in the 90's, so take it for what you will.

Thanks. I see from the side bar have been hitting this site. Let's see, recently viewed items:

"Poppy seeds: differences in morphine and codeine content and variation ..."

"Spectrum of human tails: A report of six cases ..."

"Spontaneous knotting of an agitated string ..."

Light is detected at each retina separately, and undegoes some processing in the retina. The optic nerve transmits that information to the thalamus (lateral geniculate nucleus). The lateral geniculate nucleus of the thalamus (LGN) is organized by visual field; the left thalamus receives information from both eyes about the right half of the visual field. Some cats died at the hands of Hubel and Wiesel to give you this information; AFAIK it was not studied by the national socialists in their grusome human experiments.

On the original question, neglect dyslexia can be caused by disturbance in one cortical hemisphere.

Interesting. I wonder if readers of vertically written languages are less (or maybe more) prone to dyslexia?

my recollection from cognitive linguistics, years ago, was that the dyslexia rate is affected by the complexity of mapping symbols to sounds. italian speakers had a lower rate than english speakers, for instance.

i haven't read this in its entirety, but it discusses things a bit and has a sizable bibliography: https://dyslexiaida.org/the-myths-and-truths-of-dyslexia/

"What researchers have learned so far is that writing systems vary extensively not only in their visual appearance (e.g., alphabetic vs. logographic and visual complexity) but also in many other factors such as orthographic depth and morphological complexity (the latter not discussed in the current article). Prevalence rates of dyslexia may vary somewhat across writing systems, perhaps influenced by these differences. It is important to note, however, that prevalence rate is highly sensitive to the criteria used to define dyslexia; some research groups have found essentially identical prevalence rates regardless of orthographic depth, depending on the criteria used. We have also learned that, despite these more ‘superficial’ differences, there seems to be a fundamental universal principle that dictates reading networks in different writing systems that is consistent with the goal of reading (i.e., to convey meaning). Finally, in terms of dyslexia, there appears to be a core dysfunction present across writing systems that reflects the phonological deficit hypothesis and may be driven by more subtle sensory processing deficits (Goswami, 2015). This would also make sense given the high heritability estimates of the disorder (Grigorenko, 2004)."

"The Myths and Truths of Dyslexia in Different Writing Systems"

https://dyslexiaida.org/the-myths-and-truths-of-dyslexia/

Reply on news.ycombinator.com