Sequential processing in hemispheric word recognition

The impact of initial letter discriminability on the OUP naming effect

Annukka K. Lindell*, Michael E R Nicholls, Peter J. Kwantes, Anne Castles

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Citations (Scopus)


The cerebral hemispheres have been proposed to engage different word recognition strategies: the left hemisphere implementing a parallel, and the right hemisphere, a sequential, analysis. To investigate this notion, we asked participants to name words with an early or late orthographic uniqueness point (OUP), presented horizontally to their left (LVF), right (RVF), or both fields of vision (BVF). Consistent with past foveal research, Experiment 1 produced a robust facilitatory effect of early OUP for RVF/BVF presentations, indicating the presence of sequential processes in lexical retrieval. The effect was absent for LVF trials, which we argue results from the disadvantaged position of initial letters of words presented in the LVF. To test this proposition, Experiment 2 assessed the discriminability of various letter positions in the visual fields using a bar-probe task. The obtained error functions highlighted the poor discriminability of initial letters in the LVF and latter letters in the RVF. To confirm that this asymmetry in initial letter acuity was responsible for the absent OUP effect for LVF presentations, Experiment 3 replicated Experiment 1 using vertical stimulus presentations. Results indicated a marked facilitatory effect of early OUP across visual fields, supporting our contention that the lack of OUP effect for LVF presentations in Experiment 1 resulted from poor discriminability of the initial letters. These findings confirm the presence of sequential processes in both left and right hemisphere word recognition, casting doubt on parallel models of word processing.

Original languageEnglish
Pages (from-to)160-172
Number of pages13
JournalBrain and Language
Issue number2
Publication statusPublished - May 2005



  • Barprobe
  • Horizontal
  • Left hemisphere
  • Right hemisphere
  • Serial
  • Vertical
  • Visual field

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