Cognition Laboratory Experiments

John H. Krantz, Hanover College, krantzj@hanover.edu

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Hanover College
Psychology Department

Instructions for the
Partial Report Experiment

 

When you click on the link below, you will be presented with the experiment setup screen.  On this screen will be the variables you can set to define your condition.  Here is a list of the variables and their settings

Variable Settings
Number of Trials The number of trials in the conditions from 10 to 100
Font Size Size of the font from 12 point to 64 point
Separation Distance from one character to the next both vertically and horizontally.  In multiples of character heights.  From 0.5 to 25. Be careful, this might cause some characters to go off the screen.
Wait Time Time from beginning of trial to the presentation of the letters (0 to 5000 msec).
Duration of Letter Flash The time the letters are on the screen (20 to 5000 msec)
Time between flash and arrow Time after the letters are removed before the arrow indicating the row to recall is placed on the screen (0 to 5000 msec)
Number of Items in each row The number of items that are to be recalled (2 to 20 letters). 
Number of Rows The number of rows in the array (1 to 10 rows).  The total number of letters that can be displayed must not exceed 20.
Use Masking Stimulus Indicates if the stimulus should be masked after the end of the experiment.  There are two types of masks possible, both a random visual noise and a mask made up of random letters in the same font and font size as the array.
Location of Array Is the array aligned so that it centers on the fixation or the left edge or the right edge aligns with the fixation.
Report what?  Based on You can have people respond to rows, like the original Sperling (1960) experiment, or in columns.  If you use one row, this would be like the Averbach and Coriell (1961) version of partial report.  It is also possible to have the colors randomly back by either red, green or blue backgrounds.  Then the subject is presented with a one of these colors in a square centered on the screen and the participant is to report those letters with that color.

After you have finished making your settings, press the Done button at the bottom of the screen.  The Partial Report experiment screen will then be presented. 

Press the space bar to begin the experiment.  A fixation mark will appear for the indicated time.  Then the array of letters will be flashed.  After the array has been removed, the screen will be blank.  After this blank period, an arrow will show up indicating one of the rows to recall.  Type the letters that you remember in the correct order.  If you do not remember on of the first letters, type a guess so that letters you recall will occur in the proper order.  The letters you type will be shown at the bottom of the screen.  You may use the backspace to clear letters you have typed.  When you are done, you will press the spacebar to go to the next trial.

At the end of the experiment, your results will be presented.  The results will be the proportion of correct responses.  A 1.0 is a perfect performance.  You can also get your trial by trial results.  Closing your results window(s) will take you back to the setup window so you can run another experiment.

A note on what is correct.  If the subject is to respond to either rows or columns, a correct letter has to be in the correct row or column and in the correct position.  For the colored background, the order of the letters does not matter.  To be counted correct, the letter must only be in on the proper background.

Click here to start the experiment.

References:

Averbach, E., & Coriell, A. S. (1961, January). Short-term memory in vision.  Bell System Technical Journal, 40, 309-328.

Sperling, G. (1960).  The information available in brief visual presentations.  Psychological Monographs, 74(11), 1-29.

Acknowledgements:

The idea to have responses possible both vertically and horizontally are from Amber Adkins, Matt Moore, and Dana Newton.

The idea for the letter mask is from Dwayne Guenther, Sarah Pollom, and Alexis Rose.

The idea to index letters by the color of the background is by Angela DiGernimo, Becky Nixon, and Cole Wyatt.