The Development of Visual Word Recognition

Tuesday, April 6, 2010

Accessibility:  Intermediate-Advanced

We’ve looked at brain regions and development during word related tasks (word generation, reading and repeating), but we haven’t yet looked at a straight up study of word recognition and development.



What’s the best task to use to study visual word recognition? You can have people read out loud, but that involves processes like speech generation. Likewise, reading sentences or paragraphs requires the reader to process meaning and grammar in addition to the words on the page.

One segment of the field has gravitated towards tasks of single word processing that don’t require reading at all. In this particular study, Turkeltaub and colleagues use a tall letter detection task. The subjects press a button if the word has a tall letter (like d or l). As a control condition, subjects perform the same task on false fonts. Even though you can do this task without reading the words, the assumption is that reading, being highly automatic, will occur anyways. This approach, focusing on the automatic, bottom up process, allows for a more tightly controlled study. However, it also limits the findings to that very thin slice of the reading process.

Turkeltaub and colleagues tested forty one subjects ranging from 8 to 20 years old. In the whole group, the words > symbols contrast gives activation in the left posterior temporal, left inferior frontal, and right inferior parietal regions.

The authors also looked at correlations between activation and reading ability. The trend here seems to be increasing lateralization (more reliance on left hemisphere regions and less reliance on right hemisphere regions), with reading skill.*   Interesting.  I wonder how this relates to lateralization of spoken language.

Finally, the authors looked for regions that correlated with other behavioral measures, including phonetic working memory (left intraparietal sulcus and left and right middle frontal gyri), phonological awareness (left hemisphere network, incluing posterior STS and ventral inferior frontal), and phonological naming (bilateral network, including right posterior superior temporal, right middle tempral, and left ventral inferior frontal.) Surprisingly (to me at least) there is almost no overlap between the regions for the three measures. This could either mean that these measures involve very different cognitive and neural processes, or that the automatic task used in this experiment was not suited for accurately tapping into these abilities.

*Reading ability correlated positively with activation left hemisphere frontal and temporal cortical areas, and negatively with right hemisphere posterior regions. There was no correlation in the left fusiform (visual word form area), but there is a negative correlation in right posterior fusiform. 

Turkeltaub, P., Gareau, L., Flowers, D., Zeffiro, T., & Eden, G. (2003). Development of neural mechanisms for reading Nature Neuroscience, 6 (7), 767-773 DOI: 10.1038/nn1065

3 comments:

Liz Ditz April 7, 2010 at 11:14 AM  

Livia, I was looking for something else and stumbled across this, which might interest you:

Dehaene reports on an experiment using an artificial orthography in Reading in the Brain, p. 225-228. Yoncheva, Blau, Maurer & McCandliss (2006) Strategic focus during learning impacts the neural basis of expertise in reading, Poster presented at the Association for Psychological Science Convention, New York, May 25-28.

I couldn't find anything more on the poster presentation so I went to McCandliss's faculty page, in which he reports on

Maurer, U., Blau, V.C., Yoncheva, Y.N., McCandliss, B.D. (in press). Development of visual expertise for reading: rapid emergence of visual familiarity for an artificial script. Developmental Neuropsychology

It looks like they did some EEG research as part of the research, too.

A specific component of the EEG waveform is called the N170 (since it is negative, and occurs at 170 ms). McCandliss and colleagues have several papers in press with N170 in the title:

Maurer, U., Blau, V. C., Yoncheva, Y. N., & McCandliss, B. D. (in press). N170 in learning to read a novel script: early visual familiarity enhances right lateralization. Developmental Neuropsychology.

Yoncheva, Y. N., Blau, V. C., Maurer, U., & McCandliss, B. D. (in press). N170 in learning to read a novel script: the impact of attending to phonology on lateralization. Developmental Neuropsychology.

I couldn't find any pre-pub PDFs but your access might be better.

Livia April 7, 2010 at 1:25 PM  

Thanks Liz, I'll be on the lookout for those when they come out.

Bruce McCanliss May 26, 2010 at 4:04 PM  

I've just learned that the two in press papers are finally being published next month. If you write to me in a week I can send you pre-prints. These were delayed nearly a year in the publication process after being declared accepted (don't ask me who to blame...ugh).

--Bruce McCandliss

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