**Subjects** <br> We will aim for usable data from 100 subjects per condition, for a total of 600 subjects after exclusions. Results from a previous study suggest that we can expect to exclude approximately 40% of all data collected; as such, we will recruit 1000 subjects. Subjects will be recruited through Amazon's Mechanical Turk service and will receive $0.10 in exchange for completing the experiment. Subjects must have a 95% HIT approval rate to be able to access the study. **Stimuli** <br> The stimuli consist of eight objects presented against a light blue (#58ACFA) background measuring 666 x 546 pixels. These objects consist of two triangles (53 pixel base x 53 pixel height), squares (44 x 44 pixels), diamonds (53 x 53 pixels), and circles (radius 20 pixels). One of each shape is white (#FFFFFF), and the other shapes are randomly assigned to be purple (#800080), red (#FF0000), or yellow (#FFFF00) on each trial. The sequence in which these colors appear is randomly assigned, but all possible sequences are presented. A blue (#0000FF) fixation square measuring 11 x 11 pixels is positioned in the center of the display. The unexpected object is a random shape (triangle, square, diamond, or circle), and can be either red, yellow, purple, green (#008000) depending on the condition. In the "current color" condition, the unexpected object will be the same color as the other nonwhite shapes on the critical trial. In the "previous color" condition, the unexpected object will be the same color as the nonwhite shapes in the first or second non-critical trials; the selection is counterbalanced so that each color will be selected equally often, and selected equally often from the first and second trials. In the "new color" condition, the unexpected object will be green, a color unique to the current and all past displays. **Condition Assignment** <br> Subjects can be asked to attend either to the white or nonwhite shapes. The unexpected object can be white, a random color from the nonwhite shapes, or green (nonwhite, but a color not present in nonwhite set). This yields six possible conditions resulting from the combinations of attended set (2) x unexpected object (3). Upon starting the experiment, the script counts how many subjects have completed the study so far and takes that number modulo 6. Each number 0-5 corresponds to one of the attended object x unexpected object color combinations. An additional random number, 0-5, is drawn to select the color sequence for the subject. **Procedure** <br> A demonstration of the task may be viewed [here][1]. After accepting the HIT on Amazon's website and having their worker ID confirmed as new by TurkGate [(Gideon & Goldin, 2013)][2], subjects will be redirected to an external website running the experiment in Javascript. _Instructions._ Subjects are instructed that they will see a set of objects move and bounce around, and that they will be asked to track one group of these objects and count how many times they bounce off the sides of the display window. <br> _Noncritical Trials._ Two trials. Subjects are told which set of objects, white or nonwhite, they should monitor; they are also instructed to keep their eyes fixed on the blue square in the center. Then the trial begins, and the objects bounce (roughly 5-8 times per object) around the display at randomly varying velocities for 17 seconds. Objects always pass behind the fixation square. Subjects are asked to enter the number of bounces they counted after each trial into a text box which only accepts integer inputs. <br> _Critical Trial._ The critical trial proceeds just like the noncritical trials. After 5 seconds, the unexpected object appears and travels across the experiment window from right to left, passing behind the fixation square. It remains on screen for 6750 ms. The trial terminates after 17 seconds total. Subjects are asked to report their count, and then are asked whether they saw something that had not been present on the previous trials. Then they are asked to select the shape and color of the object from a set of pre-determined options, or to guess if they did not notice anything. <br> _Demographic Questions._ Subjects are asked to select their age range, gender, country of residence, whether their vision needs correction and if they were wearing it during the experiment, the status of their color vision, the number contained in Ishihara Plate 9, whether they experienced any problems with playback, and whether they had prior experience with a similar inattentional blindness task. After submitting their final response, subjects are presented with a completion code and told to return to Mechanical Turk to enter the code and receive payment. [1]: http://simonslab.com/mot/color_demo.html [2]: https://github.com/gideongoldin/TurkGate/wiki/Installation