"This study compares threeforms of instruction provided to English-speaking adults learning to read Hangul Korean. Instruction provided an initial focus on either small grain units (letters), medium grain units (syllables), or large grainunits (words)."

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Note added at 1 hr (2019-08-22 16:15:55 GMT)
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5098455/
"Thirty-seven monolingual, literate English-speaking adults were trained on a novel artificial orthography given initial instruction that directed attention to either large or small grain size units (i.e., words or letters). We examined how initial instruction influenced processing speed (i.e., reaction time (RT)) and sensitivity to different orthographic grain sizes (i.e., rimes and letters). Directing attention to large grain size units during initial instruction resulted in higher accuracy for rimes, whereas directing attention to smaller grain size units resulted in slower RTs across all measures. Additionally, phonological awareness skill modulated early learning effects, compensating for the limitations of the initial instruction provided. Collectively, these findings suggest that when adults are learning to read a second orthography, consideration should be given to how initial instruction directs attention to different grain sizes and inherent phonological awareness ability."