The letter frequency effect is an effect of letter frequency, according to which the frequency with which the letter is encountered influences the recognition time of a letter. Letters of high frequency show a significant advantage over letters of low frequency in letter naming,[1] same-different matching,[2] and visual search.[3] Letters of high frequency are recognized faster than letters of low frequency.[4] Appelman and Mayzner (1981) in their re-analysis of the studies concerning letter frequency effect have found that in 3 out of 6 studies using reaction times (RTs) as a dependent variable the letter frequency correlated significantly with RTs.[5]
Majority of studies on letter frequency effect failed to find a significant letter frequency effect.[6] These studies, however, used the same-different matching task[6] in which the participants see two letters and are to respond if these letters are same or different.[6] Therefore, the absence of letter frequency effect in these studies may be due to the participants using the visual form of a letter instead of a letter itself to match the letters.[6]