PSY 321:  Cognitive Processes
Mental Rotation

In this experiment you will see a pair of objects such as these:

The objects can be either identical to each other, except that one is rotated relative to the other, or they can be mirror images of each other with one object rotated relative to the other.  The above objects are identical to each other.  The objects below are also identical to each other, except that the object on the right has been rotated 90° relative to the object on the left.  That is, if you rotate one of the objects 90° then the objects will be identical.

The following pair of objects are mirror images of each other.  You cannot rotate one object to make it identical to the other:

The last pair of objects are mirror images of each other as well.  However, the object on the right has been rotated 90° relative to the object on the left.  You cannot rotate one object to make it identical to the other.

You will see 64 pairs of objects like those above.  Thirty two of the pairs of object will consist of identical (same) objects except for rotation and thirty two of the pairs of objects will be mirror images of each other (different) with rotation.  There will be four pairs of identical (same) and four pairs of mirror image (different) objects at each of eight angles of rotation: 0°, 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, and 157.5°.  The 64 pairs of objects will be presented in a different random order for each participant.

Your task is to look at the pair of objects and say whether they are identical (same), except for rotation, or mirror images (different) except for rotation.  If you believe that they are the same, you are to press the "S" key on your keyboard; if you believe that they are different, you are to press the "D" key on your keyboard.  You are to maintain a high level of accuracy -- at least 90% accurate is desirable; if you are less than 75% accurate in the task, your data will not be saved and you will have to try again.  Within the constraint of being highly accurate, you are to respond as quickly as you can while maintaining a high level of accuracy.  After responding, the screen will be cleared for 1 second and the next pair of objects will then be displayed.

Once you have finished viewing and responding to the 64 pairs of objects, your speed and accuracy results for each angle of rotation and for the same vs. different images will be displayed.  You should then submit your data to the web server so that it can be stored with the rest of the data from your classmates.