Specs for OCCLUDE1 Program

 

 

 

 

OVERVIEW

 

Subjects will see 6 pictures (jpeg images), each for 30 seconds.  They are trying to “memorize” the pictures.  At the end, they will be tested by attempting to draw what they saw.  This test won’t involve the computer.

 

There are two presentation conditions.

 

Constant Condition:  Here the picture comes up for 30 seconds and stays up, then disappears.

 

Toggle Condition.  Basically, the subject’s view of the picture keeps getting partially obscured, allowing them to mentally try to recreate what that portion of the picture looks like.    First, the picture comes up for four seconds.  Then 1/6 of the picture is obscured by a square as shown below.  Randomly select a zone and put up a black rectangle over it.  This stays up until the subject “toggles” (presses the space bar) at which point the whole picture comes into full view again.  After 4 more seconds or when the subject presses the space bar (whichever comes first), a different zone gets obscured.  This square stays up until the subject “toggles” … and so on.  Never repeat zones with a spacing of less than 3.  I.e., keep randomly choosing a zone until you have one that differs from the previous zone, the one before that, and the one before that.  So you could have this sequence: 1 4 2 3 1 6…

but not 1 4 2 1 6…

 

So the subject views the picture with one zone obscured until he presses the space bar.  He never sees the entire picture for more than four seconds (he can choose to see it for less).

 

 

Here’s an example of a picture with Zone 2 obscured.

 

Text Box: ZONE3

 

 

 

 

INSTRUCTIONS TO THE SUBJECT.

 

This is an experiment on memorizing pictures.  You will see six pictures, viewing each one for 30 seconds.  Your job is to try to memorize the contents of the pictures.  At the end, we will ask you to sketch very roughly what you saw in each of the six pictures.  The two people who do the best job of memorizing the contents of the pictures (as judged by our research assistants) will receive a $20 prize after the conclusion of the experiment.

 

Some of the pictures will remain on the screen for 30 seconds of continuous viewing.   For the other pictures, however, the computer will hide part of the picture by putting a black rectangle over a large portion of the picture.  Whenever this happens, you should “test” yourself by trying to visualize what is in the portion of the picture that is obscured.  When you are ready to continue, press the space bar.  Then the whole picture will come into view.  After four seconds (or whenever you press the space bar again), a different part of the picture will be hidden, and so it will continue.  To give you a sense of how this hiding/unhiding works, let’s try a sample picture.  This will NOT be one of the pictures you are tested on.  CLICK TO TRY SAMPLE PICTURE.

 

If you have any questions, please ask the research assistant now.  CLICK TO BEGIN EXPERIMENT.

 

Before you put up each picture, pause, and say “The next picture will be exposed continuously for 30 seconds” or “The next picture will be hidden/unhidden.”

 

DESIGN.

 

First ask the experimenter to type in an Order Condition Number.

 

The design is extremely simple.  I will give you six pictures, all the same size, labeled picture1.jpg, …, picture6.jpg.  You will show every subject these six pictures in this order!  However, whether the picture is continually exposed or hidden/unhidden will depend on the order condition in this way:

 

 

PICTURE                    COND FOR SUBJECT                      COND FOR SUBJECT

                                    IN ORDER CONDITION 1                  IN ORDER CONDITION 2

 

1                                  Continuous                                          Hidden/Unhidden

 

2                                  Hidden/Unhidden                                 Continuous

 

3                                  Continuous                                          Hidden/Unhidden

 

4                                  Hidden/Unhidden                                 Continuous

 

5                                  Continuous                                          Hidden/Unhidden

 

6                                  Hidden/Unhidden                                 Continuous

 

 Data Storage  The only thing you have to save is subject’s initials, subject number, order condition, and what pictures were presented and whether they were hidden or unhidden (yeah I know, the last part is all inferable from the order condition, but it’s nice to have internal checks of everything).

 

At the end of the study say “Thank you very much for participating – Please call your experimenter for your memory test.”