The Great Vowel Shift occurred in the twelfth century until the eighteenth century, but had its main effect in the fifteenth and early sixteenth centuries, the sounds of the long stressed vowels in English changed their places of articulation or how sounds are made. Old and Middle English were written in the Latin alphabet. After the shift, many thought that the pronunciation of English had changed dramatically from its visual representation and a new alphabet was needed. Therefore, in the sixteenth century, the first attempts to reform the English spellings occured.