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Project Summary

Difficulty	6
Time required	Very Short (a day or less)
Prerequisites	None
Material Availability	Readily available
Cost	Very Low (under $20)
Safety	No issues

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Objective

In this experiment you will test if changing the number of distracters will affect the ability of an observer to find the target during a visual search.

Introduction

Have you ever looked and looked desperately for something? It is so frustrating! The classic example is when I lose my keys. You would think that by now (knowing that I am the kind of person who often loses my keys) I would have a huge, bright red key chain with a blinking strobe light that plays a ring tone every time I lose them. But of course, I still have them on a plain-old key ring. Hence the frustration.

But I can turn this story from lemons into lemonade. It turns out that this frustrating situation is the perfect example of performing what cognitive psychologists call a visual search. During a visual search, an observer (me) looks for a target (my keys) in the midst of distracters (all of the other stuff in my messy house). By making my key chain easier to see, I could have improved upon my visual search, and made my search more successful.

What properties are important for performing a successful visual search? Try this quick activity to help you think about the variables. In which of the two images below can you find the red letter "T" the fastest?

Which side has the easier task? (Busey, date unknown)

It was probably the image on the left. The image on the right has more complex distracters than the image on the left, making finding the target (the red letter "T") more difficult. In this experiment you will use an online program to design your own visual search experiments to test whether changing the number of distracters will affect your visual search. Will increasing the number of distracters make your search more difficult?

Terms, Concepts and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the Internet, or take you to your local library to find out more!

• Visual Search
• Observer
• Target
• Distracter

• What variables affect a visual search?
• How can a visual search be made more successful for the observer?
• How will changing the number of distracters affect the success of finding the target during a visual search?

Bibliography

• This experiment uses an online Visual Search test written by Dr. Tom Busey at the University of Indiana, Bloomington:
  Busey, T., date unknown. "Visual Search Experiment," Department of Psychology, Indiana University, Bloomington. [accessed September 6, 2007] http://cognitrn.psych.indiana.edu/CogsciSoftware/VisualSearch/
• Another version of this project can be found at the CogLab online lesson "Visual Search" from Wadsworth Publishing (password required to use their java application):
  CogLab, 2007. "Visual Search," CogLab 2.0 Online Laboratory, Wadsworth Publishing. [accessed September 6, 2007] http://coglab.wadsworth.com/experiments/VisualSearch.shtml
• Here is background reading about visual search from Wikipedia:
  Wikipedia contributors, date unknown. "Visual search," Wikipedia, The Free Encyclopedia. [accessed September 6, 2007] http://en.wikipedia.org/w/index.php?title=Visual_search&oldid=153930412
• Two classic children's book series that are based upon the Visual Search Principle are the "Where's Waldo" and the "I Spy" books. Here is the original book from each series for you to check out:
  • Handford, M., 1987. Where's Waldo? , New York, NY: Little Brown & Co.
  • Marzollo, J., 1992. I Spy: A Book of Picture Riddles, New York, NY: Scholastic.

Materials and Equipment

• Computer with Internet connection

Experimental Procedure

1. In your web browser, go to the Coginitive Science Visual Search page developed by Dr. Tom Busey.
2. Depending upon what Internet browser you have and whether the necessary Java is enabled on your computer, you will either need to run the Java applet directly from the webpage or download the software on your computer before using it.
   1. To use the Java applet simply select the "Run Applet" button.
   2. Or to download the software, click on the movie link and follow the instructions to download the software to your desktop. After you have downloaded and copied the necessary files, start the Visual Search Experiment by clicking on the Visual Search icon on your desktop.
3. Select the "Targets" tab at the top of the webpage. Be sure that only one target display box is checked. Your page should look like this:

4. In the "Targets" tab there is a drop-down menu to change the target object to anything you like. I am going to select the hotdog as my target:

5. Once you select the new target, you should see it in the box for "Target 1". (You can ignore the other Targets 2–4 because they are unchecked and will not show up in your display):

6. Now click on the "Distracters" tab at the top of the webpage. Again, be sure that only one target display box is checked. Just like with the target page, you can click on the drop-down menu to select a new Distracter. I have chosen a hamburger as my distracter. Once you select the new distracter, you will see it in the "Distracter 1" box:

7. Next click on the "Do Experiment" tab and be sure the "Use Circular Display" box is UN-CHECKED! Then click on the "Start Experiment" button and follow the instructions.

8. When you are done, it will instruct you to click on the button below to quit and view your results, which will show up on the "Do Experiment" screen. Now the screen will have your results. Pay attention to the "Percent Correct over all trials" box in the lower right-hand corner:

9. Write down your "Percent Correct over all trials" result in a data table:

   Number of Distracters	Type of Distracter	Percent Correct (over all trials)
   1	hamburger
   2	pizza
   3	etc.
   4	etc.

10. Now go back to the "Distracters" tab and add another distracter. To add Distracter #2, you need to check the "Display Distracter 2" box, and then select a distracter from the drop-down menu. I added pizza!

11. Repeat the experiment and write the "Percent Correct over all trials" result in your data table
12. Repeat adding a third, and then a fourth distracter to your experiment, writing the "Percent Correct over all trials" result in your data table each time.
13. Repeat this procedure on at least four more people, and record the results of each volunteer in a data table.
14. When you are done, you will need to calculate the "Average Percent Correct over all trials" for each number of distractors in your tests. Do this calculation by adding together the scores of all five test subjects (including yourself) with one distractor present and dividing your answer by five. Repeat this calculation for scores with 2 distractors, 3 distractors, and 4 distractors present.
15. Make a graph of your data. Make a scale of the "Average Percent Correct over all trials" on the left side of the graph (y-axis) from 0–100. Make a scale of the "Number of Distracters" on the bottom of the graph (x-axis) from 1–4. Draw a bar for each result up to the corresponding "Average Percent Correct over all trials" number.
16. What happened to the "Average Percent Correct over all trials" as you added more distracters? What do you think this means?

Variations

• You can change other variables as well, here are some ideas to try:
  • Change the number of targets instead of distracters
  • Measure response time instead of the percent correct
  • Change the number of images by changing the number of rows and columns
  • Use different symbols, like letters or numbers
  • Change the colors of the target and distracters
• Can you think of real world applications for this cognitive test? See if you can investigate the use of visual search properties in any of these areas:
  • Designing logos and brand names to be noticed
  • Designing webpages that are easy to navigate
  • Finding points of interest on a map
  • Displaying data in a way that shows what is important
  • Any other application that you can imagine—just think of a way to test it!

• For more science project ideas in this area of science, see Human Behavior Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2007-09-18 22:00:00

Career Focus

If you like this project, you might want to think about career opportunities in Human Behavior.

Why people take certain actions can often feel like a mystery. Psychologists help solve these mysteries by investigating the physical, cognitive, emotional, or social aspects of human behavior and the human mind. Some psychologists also apply these findings in order to design better products or to help people change their behaviors. Learn more about this career: Psychologist.