College of Science and Health Theses and Dissertations

Date of Award

Summer 8-23-2015

Degree Type


Degree Name

Master of Science (MS)



First Advisor

Pablo Gomez, PhD

Second Advisor

Kimberley Quinn, PhD


This thesis examines the effects of Turkish vowel harmony in visual word recognition. Turkish is among a few languages with vowel harmony, which is a process in which words contain vowels only from one specific vowel category. These categories are defined by the vowel’s phonological qualities (i.e., similar mouth and lip movement in pronunciation). In Turkish, categories depend on the vowel’s roundness/flatness, backness/frontness and whether the vowel’s pitch. Vowel harmony occurs naturally in language and is not taught formally. Instead, it is believed to occur due to decreased effort of words with vowel harmony in speech production (Khalilzadeh, 2010). Vowel harmony is very common in Turkish, with over half of all Turkish words (root words and affixes), containing vowel harmony (Güngör, 2003). Turkish is particularly interesting because it contains two types of vowel harmony: primary and secondary vowel harmony. Primary vowel harmony depends on the frontness and backness in vowels and secondary vowel harmony depends on whether a vowel is high or low pitch, in addition to the roundness and flatness. Although vowel harmony is very common, disharmony exists among some native Turkish words, foreign loanwords and compounds. Vowel harmony was explored in this thesis within the context of reading, with a focus on primary vowel harmony. There were two studies, including three experiments. The first study consisted of the development of a database of words in Turkish. The database includes all words from an obtained Turkish lexicon, the number of vowels in each word, the word length, whether the word has primary or secondary vowel harmony, word frequency and the syllabified version of each word. The second study consisted of three separate lexical decision task experiments, with each having 30 Turkish speaking participants. Experiment 1 consisted of a straight lexical decision task, with a 3 (Target harmony type: front harmony, back harmony, no harmony) x 2 (Target type: word, nonword) design. Experiments 2 and 3 were masked priming studies with word (Experiment 2) and nonword (Experiment 3) primes, in a 3 (Prime harmony type: front harmony, back harmony, no harmony) x 3 (Target harmony type: front harmony, back harmony, no harmony) x 2 (Target type: word, nonword) design. As predicted for Experiment 1, words with vowel harmony had faster and more accurate responses than words without vowel harmony. Nonwords with back vowel harmony had slower and less accurate responses than nonwords without harmony, which was also in line with the prediction. For Experiments 2 and 3, it was predicted that matching harmony types (i.e., front vowel harmony prime - front vowel harmony target) would have faster and more accurate responses. Results of Experiment 2 did not support the prediction in both latency and accuracy. Results of Experiment 3 supported the predicted results in both latency and accuracy. Overall, the results these experiments suggest that primary vowel harmony facilitates word recognition. This is believed to occur due to the usage of phonemic cues in word recognition. Past research has shown that both phonology and orthography is involved in word recognition, especially in languages with shallow orthography such as Turkish (Frost, 1998; Katz & Frost, 1992). In addition, it has been shown that words with harmony are easier to pronounce (Walker, 2005). Word recognition could have been facilitated since vowel harmony is a phonological category of words that are easier to pronounce.

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