In this experiment every trial will be more or less the same: You will see 2 columns of dots. Dots in one of the columns will be changing size continuously. Your task is to choose which column that is.

Please note that in some trials, dots in all two columns will be moving, while in other trials, they will both be stationary. This is not important as far as your task is concerned. You just need to choose which column has dots that are changing size.

When doing the experiment, please keep your fingers on the numbers 1 and 2 keys. The dots on the screen will be side by side. 1 refers to the left column, 2 refers to the right column. The boxes will be labeled with numbers to remind you. Your job: press the appropriate 1 or 2 key on the keyboard as fast as you can to indicate which column has dots that are changinge size. If possible, please maintain a viewing distance of approximately 57 cm (around 22.4 inches). That's about the distance of a fully outstretched arm touching the screen from where you are seated.

After you have made your choice, you will be invited to move on to the next trial. Before each trial begins please fixate the square in the center of the screen.

Click 'start training' when you are ready to see the training trials.

Training is now complete. The experiment is about to start. The experiemnt will take around 7 mintues.

Click 'start experiment' when you are ready. Remember, your job is to press 1 or 2 key on the keyboard as fast as possible to indicate which column contains dots that are changing size.

Click 'next' to continue.

The experiment is finished. Please clikc 'submit' to submit your data. Thank you.