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Objective: In our daily lives we attend to very different stimuli in our environment and yet we have the ability to selectively attend to some. In this study we tried to understand the effect of secondary distractor stimulus on the selective attentional performance and how it is influenced by the physical properties of the stimuli. Methods: 90 participants (age Mean±STD=19.26±1.95) joined a computer-based visual attention task in which they were asked to attend and respond to a simple visual stimulus appearing from different locations, while they are interrupted by a secondary stimulus of different color, location and for different times. The task was written in JAVA programming language and the analysis was made by SPSS. Results: A secondary stimulus presented during a primary attention task had differential effects, based on its color and location. Red stimulus was shown to decrease the response time upon a primary stimulus specifically in the location it was presented (p<.003) (without any significant change in the accuracy of the response (p<.154)). We saw a similar effect for a secondary blue stimulus, but it took a longer time to exert its effect compared to red (response time: p<.043; accuracy: p<.784). In addition to the color, these effects of distractors significantly varried upon its location in the visual area as well as its duration. Some of the visual areas were more sensitive to the distractors compared to others and the increased duration of each distractor enhances its effect (1s vs. 1 ms exposure, Δresponse times: 175.19 ms vs.156.52 ms). Conclusion: The results indicate that a secondary stimulus exerts its effect on attentional response to a primary stimulus, based on where it is presented and for how long. It also has differential effects when presented in different colors, which supports that our visual attention system has differential sensitivity for stimulus of different physical properties. [ABSTRACT FROM AUTHOR]