Three letter rule poets such as John Milton alternated between short and long forms for function words, depending on whether they occurred on or off the meter. For instance: While many function words have more than two letters ("and", "she", "were", "therefore", etc.), the exceptions to the rule are rather two-letter content words. Only a few of these occur commonly in most texts: the words "go" (which also has a functional usage in the idiom "going to do something"), "ox" and, especially in American texts, "ax". English grammar is relatively flexible about converting words of one class to another, allowing verbal uses such
Missing letter effect circle a target letter every time they come across it while reading a short passage. The missing letter effect is more likely to appear when reading words that are part of a normal sequence, than when words are embedded in a mixed-up sequence (e.g. readers asked to read backwards). Two primary hypotheses tried to explain the missing letter effect: Healy (1994) emphasized identification processes playing a crucial role, almost entirely focusing on word frequency. However, Koriat & Greenberg (1994) viewed the structural role of the word within a sentence (i.e. function words vs. content words) to be crucial. Both accounts