Most people report seeing columns, but it is really just a collection of dots. The perception of columns comes from the fact that the dots are closer to each other vertically than they are horizontally. This finding is just one of the interesting features about perception that was discovered and systematized by the Gestalt psychologists early in the 20th century into what is known as the Gestalt Laws of perception. We group together disconnected bits of a scene into a more complete perception. This is quite useful in the real world because one object often overlaps part of another object, so we need to be able to group these unconnected parts of objects together.
One classic illusion -- the Kanizsa Illusory Contours -- is shown below.
Most people see a triangle overlapping three circles. Of course, there is no triangle, just slices out of the three circles. These circles are often called Pac-Man figures because of their similarity to the character in the classic video game of the same name. The current experiment will examine how this illusion arises.
References:
Kanizsa, G. (1979). Organization in Vision: Essays on Gestalt Perception. New York: Praeger.
1.2Experiment Setup
Figure 1.3
1.3Instructions
Instructions
You will need to press the space bar to begin the experiment. At the beginning of each trial, a fixation mark will appear. Keep your eyes positioned on this mark as much as possible. A figure will flash around the fixation mark. This is called the prime stimulus. Then, following a brief blank period, when just the fixation mark is present, two shapes will be presented. One shape will be on either side of the fixation mark. The shapes will be either squares or triangles. Your task is to determine if the figures are the same or different. You may respond by using the buttons below the images or the keyboard.
Keyboard Responses:
Key
What Response Means
F
Same
J
Different
1.4Experiment
Begin Experiment
Start Experiment
Figure 1.4
1.5Results
Results
Figure 1.5
1.6Quiz
Quiz
Question
1.1
One independent variable for this experiment is:
A.
B.
C.
D.
1
Incorrect.
Correct.
The independent variable is the value that is changed by the experimenter. In this experiment, one independent variable is the type of prime presented, whether no prime, an illusory triangle, or an illusory square.
Question
1.2
The primary dependent variable in this experiment is:
A.
B.
C.
D.
1
Correct.
Incorrect.
The dependent variable is the value the experimenter collects to indicate how you performed in the experiment. In this case, we measured the time it took you to determine if the two shapes are the same or different, so this is reaction time.
Question
1.3
What is illusory about the illusory triangle or square used in this experiment?
A.
B.
C.
D.
1
Correct.
Incorrect.
What makes these triangles and squares illusory is that there are no edges or brightness changes only corners and yet we see edges and clear triangles and squares.
Question
1.4
What are the typical findings in this experiment?
A.
B.
C.
D.
1
Correct.
Incorrect.
The correct answer is that having a prime of the same shape as the target leads us to respond faster.
Question
1.5
The use of perceiving disconnected corners as part of a whole figure is a clear example of the _______ approach to understanding perception.
A.
B.
C.
D.
1
Correct.
Incorrect.
These illusory figures are a classic example of a Gestalt approach to perception.