This experimental investigation deals with the functioning of human attention. It is based on a replica of the well-known “Stroop Effect” carried out in 1935 by John Ridley Stroop. The purpose of this experiment was to demonstrate how difficult it is for a person to divide attention into several tasks, by having participants read a series of three stimuli which consisted of: 1) color words in black ink, 2) color words in color of the actual font, and 3) coloring the words with different ink, where the participant reads the font instead of the present word. The research hypothesis assumed that selective attention was easy to perform both visually and auditorily. The controlled variable of the experiment was the black ink color words, while the second stimulus was considered the experimental variable. There were two independent variables: the colored words corresponding to their color and the number of errors each participant made in each category. The dependent variable was the third stimulus, in which the participant read its character rather than the presented word. The experiment was completed with a group of sixteen participants aged 13 to 16 (eight girls and eight boys in total). The average time and errors in each variable were as follows: 9.28 seconds with no errors, 9.53 seconds with one error, and 25.53 seconds with an average of two errors. In conclusion, the observations were that it took much longer on the last stimulus, which was the one that divided attention into two tasks. The implications results would correspond to the minimum number of participants in the experiment. The aim of the experiment was to discover the implications that attention has when used in two different tasks. This winter... middle of the paper... my day at almost the same time. They too were tested one at a time, while the others remained in the classroom without being exposed to what they would do when it was their turn. If the words were provided in the participant's native language, there would be greater reliability of the results as it was their most proficient language. Two of the participants conducted the experiment later in another environment. Works Cited "BACKGROUND ON THE STROOP EFFECT". Rochester Institute of Technology. Network. 16 February 2010. ."BDoughertyAmSchool - IB Information - Grade 11." BDoughertyAmSchool - home. Network. 16 February 2010. "Selection of participants -." Participapedia. Network. February 16. 2010..