Experiment Description: Mental Rotation
The study of mental rotation began with the classic work of Shepard
& Metzler (1971) and is described in detail in the first part of
Chapter 7 in Matlin (2005). Demonstration 7.2 involves the actual
three-dimensional stimuli that were used in Shepard and Metzler's
(1971) original mental rotation task. In their study, participants
were shown two shapes and asked to decide whether they were the same
shape or mirror images. As the figure in Demonstration 6.1 indicates,
the second shape was created by rotating the original object (or a
mirror image of the object) around a central axis (depth or picture
plane). Participants reported that to complete the task, they mentally
rotated one of the shapes to bring it into alignment with the
other. Consistent with their participants' reports, Shepard and
Metzler (1971) found that the greater the angle of rotation between
the two objects, the longer the decision (see Figure 7.1, p. 213). In
other words, just as it takes longer to physically rotate an object a
greater distance, the mental rotation of an imagined object follows
that same principle.
In this experiment, a normal letter or a reversed letter will be presented
in different angles of orientation and you will be required to indicate
whether the letter is normal or reversed as quickly as possible. There will
be eight different conditions that represent different angles of rotation.
You will test whether your reaction time to make your decision (i.e. the
dependent variable) is systematically related to the angle of rotation
(i.e. the independent variable). You will examine this relation between
rotation angle and response time for both positive responses (i.e. the letter
is normal) and negative responses (i.e. the letter is reverse).
Participant Instructions: Mental Rotation
On each trial in this experiment, a plus sign will appear briefly in
the center of the screen for 500 milliseconds followed by large
upper-case 'F'. The letter F will be presented at one of eight
orientations, and will either be a normal 'F' or a
reverse/mirror-image of an 'F'. Your task is to determine whether the
symbol is a normal or a reversed 'F', and to respond as quickly as
possible by pushing the "Z" key if the symbol is reversed, or the "/"
key if the symbol is normal. The computer key assignments will be
displayed at the top of the screen but you may also want to tape the
terms 'normal' and 'reversed' to the appropriate computer keys to help
you keep track of the computer key assignments.
If the response is correct, the next trial will begin in 1500 milliseconds.
If the response is not made within 5 seconds, or if the response was incorrect,
or if an invalid key was pressed, a brief tone will be presented and the next
trial will begin in 1500 milliseconds. The stimulus is equally likely to be
normal or reversed at each of the eight orientations.
There are 3 trials at each of the 8 orientations for each symbol
(reversed or normal) for a total of 48 trials per block. There are 5 blocks
of 48 trials but the first block is a practice block and will not be used
in the calculation of the summary data. Nevertheless, the practice trials
are important for you to focus on the task and practice making your
decision as quickly and as accurately as possible. You will have an
opportunity to take a short break between lists.
The raw data from the experiment (192 responses) will be placed in a file
called DROT.DAT on your computer and can be examined by using the View
Raw Data button.
To summarize this data, click on the Analyze Raw Data button to compute
the mean and standard deviation of the reaction times for correct responses
in each of the eight orientations for each type of response (reverse image
vs. normal image). This button will also calculate the number of valid trials
for each condition or the number of trials where a correct response was
The summarized data will be placed in a file called AROT.ANL on your
computer. To view the results, click on the View Summarized Data button. This
summary data is important and will be necessary to prepare an APA style figure
to include with your paper. AROT.ANL is a simple text file and can be read
and printed with any word processor. Please note that although the summary
data appear in tabular form, the format is not in APA style.
There should be 16 sets of data that will look like the following.
|Orientation = 0 Response Type = 1|
The first line specifies the condition by describing the Orientation and Response Type
using the legend below. The second line provides the actual reaction
time in milliseconds, standard deviation, and the number of valid trials. In the
example above, the average response time for the condition where the target was
a normal F in the vertical orientation was 1087.33 ms with a standard deviation of
182.33 based on 12 trials. As indicated earlier, there are eight different orientations
and two response types that produce 16 separate conditions.
|0 = 0°or vertical|
|1 = 45° clockwise from vertical|
|2 = 90° clockwise from vertical|
|3 = 135° clockwise from vertical|
|4 = 180° clockwise from vertical|
|5 = 225° clockwise from vertical|
|6 = 270° clockwise from vertical|
|7 = 315° clockwise from vertical|
|1 = Normal F|
|2 = Reversed F|
In your graph, plot the orientation variable on the abscissa (X axis)
with reaction time on the ordinate (Y axis). The abscissa should have 8 marks,
one for each angle of orientation. Use separate lines for the
normal and reversed figure responses.
To view the results of previous participants, click on the Display Group Data
button. This button will display the average reaction time for the three
conditions. You can use this information to compare with your own performance.
If you have successfully installed Java Web Start but you are still
being taken to the Java installation page, please click on this direct link to the experiment installer.