Effect of Two Trigram-Words Displayed at Different Visual Angles on Word Recognition Accuracy and Reaction Time


  • Aung Soe Moe
  • Chailerd Pichitpornchai
  • Kittipun Arunphalungsanti


Correct rate, orthographic processing, reaction time, trigram, visual angle, visual span


The objectives of this study were to study visual recognition accuracy (correct rate – CR) of reading and reaction time (RT) responses when two trigram-words presented at different visual angles. Thirty graduate students were recruited. Each pair of trigram-words were shown at 1, 2, and 3 degrees of arc from the center
of the fovea (horizontal visual angles of 2, 4, and 6 degrees), in three experimental blocks. Each block used a total 180 pairs of trigram-words comprising Type 1 (two identical trigram-words, e.g. “pan-pan”), Type 2 (two completely different trigram-words, e.g. “pan-box”), and Type 3 (different only the middle letter of
trigram-words, e.g. “pan-pin”) stimuli. The participants were instructed to press button “1” if the two-words shown were identical, and press button “2” if they were different, as quickly as possible. CRs and RTs were recorded. The results showed that CR of Type 1 stimuli was highest at 2 degree apart when compared with those at 4 and 6 degrees apart, indicating that two identical words could be identified best at the foveal edge (at the edge of 2 degrees in diameter). At 6 degree, CR of Type 2 stimuli was highest, followed by Type 3 and Type 1 stimuli, respectively, indicating that at peripheral vision, completely different words could be easiest identified. Moreover, RTs of Type 2 stimuli were shortest, and CRs of Type 2 stimuli were highest in every visual angle. These findings were the first to show that completely different words recognitions were not affected by wider visual angles, possibly caused by orthographic processing of different word shapes. These data can be used for further developing reading training software for improving visual span.


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Author Biographies

Aung Soe Moe

Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.

Clinical Laboratory Department, No. (5) Military Hospital, 300-bedded, Mawlamyaing Township, Mon State, Myanmar 12012.

Chailerd Pichitpornchai

Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.

Kittipun Arunphalungsanti

Department of Physical Therapy, Faculty of Health Science, Christian University, Nakornpathom, 73000, Thailand.






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