### Demo A demonstration of the task, exactly as subjects would experience it but without data collection, is available [here.][1] ### Subjects We will recruit subjects expecting to exclude approximately 50% of our data. In order to end up with 100 subjects per exposure time per onset type (6 conditions), we will recruit 1200 subjects total. In order to accept the HIT, subjects will have to be based in the US, have a HIT approval rating of 95% or higher, and have completed at least 100 HITs. Subjects also must not have done a previous experiment in the lab; we will screen for this using TurkGate. ### Materials and Procedure The tracking task, stimuli, unexpected object appearance, and post-trial survey are identical to those used [in Experiment 1.][2] The only change is to the onset and movement behavior of the unexpected objects. #### Unexpected objects Unlike in Experiment 1, in which unexpected objects crossed a span of the display that was centered around fixation, the unexpected objects in Experiment 2 cross a span that is flush with the edge of the display. In this experiment, they remain vertically centered at 300 pixels from the top of the display. There are three possible durations an unexpected object can be on screen: 1.5 seconds, corresponding to a distance of 140 pixels (20% of the total horizontal distance of the display); 2.67 seconds, corresponding to a distance of 280 pixels (40% of the total display width); and 5 seconds, corresponding to a distance of 560 pixels (80% of the total display width). In addition, there are two possible ways an unexpected object can move through the display. The unexpected object can either onset from the edge of the display and offset by disappearing behind an invisible occluder in the middle of the display, or it can onset by appearing from behind an invisible occluder in the middle of the display and offsetting at the edge of the display. In the 1.5s and 2.67s condition, the object does not pass behind the fixation point at all. See the figure below for a schematic of the possible paths the unexpected object can take: ![enter image description here][3] As in the previous experiment, the unexpected object will always exit the screen when 2 seconds remain in the trial. [1]: http://simonslab.com/mot/temporal_mot_nc_demo.html [2]: https://osf.io/nwkch/wiki/home/ [3]: https://mfr.osf.io/export?url=https://osf.io/h45ka/?action=download&mode=render&direct&public_file=False&initialWidth=684&childId=mfrIframe&parentTitle=OSF%20%7C%20ex2_ux.jpeg&parentUrl=https://osf.io/h45ka/&format=2400x2400.jpeg