Term of Award

Summer 2014

Degree Name

Master of Science in Experimental Psychology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Psychology

Committee Chair

Bradley R. Sturz

Committee Member 1

Ty W. Boyer

Committee Member 2

Lawrence Locker, Jr.


The Stroop task, in which participants identify the font color of a word which names an incongruent color, has long been used to investigate attentional processes; however, there is still debate concerning the source of the effects produced by the task. The semantic competition hypothesis posits that interference results from competing semantic processes associated with the word and color dimensions of the stimulus prior to response selection. The response competition hypothesis posits that interference results from competing responses for articulating the word versus the color dimension at the time of response execution. Sturz, Green, Locker, and Boyer (2013) designed a Delayed Match-to-Sample Stroop task to differentiate between semantic and response based effects. Though the results supported a semantic competition hypothesis, it is still unclear whether the results globally supported semantic interference as the source of the Stroop effect or whether the effect was contextually driven by the DMTS task. In Experiment 1, a sequentially presented MTS task with no retention interval was implemented and the results replicated the findings of Sturz et al. Experiment 2 consisted of a simultaneously presented MTS task, where sample and response options onset concurrently for the duration of the trial. RT’s on incongruent Stroop stimulus trials were significantly longer than neutral or congruent Stroop stimulus trials. Accuracy data indicated asynchronous interference of words on color matching and no interference of color on word matching. Together, these results provide converging evidence consistent with a semantic competition account and inconsistent with a response competition account.