Can parafoveal-on-foveal effects be obtained when reading an unspaced alphasyllabic script (Thai)?

One controversial question in the field of eye movements and reading is whether there is evidence of parafoveal-on-foveal effects. This is an important issue because some models of eye movements in reading make quite different predictions in this respect (e.g., E-Z Reader vs. SWIFT models). The aim of the current study was to investigate if parafoveal-on-foveal effects occur when reading Thai, an unspaced, alphasyllabic orthography. Word frequency (high and low) of the word to the right of the currently fixated word was manipulated to examine if it would influence processing of the fixated word. Thirty-six participants read single sentences while having their eye movements monitored. There was no evidence of the effect of word frequency of the parafoveal word on fixation duration measures of the foveal word, as assessed by p(H₀∣D) values—except for a marginal effect in the skipping rates. Thus, the present data are in line with previous studies using spaced Indo-European languages which have found small/null results for parafoveal effects of word frequency during one-line sentence reading.