Memory and Cognition

The design of the experiment was “with-in subjects” as all subjects were exposed to the same tasks and same set of stimuli. The two manipulated (or independent) variables were the orientation (normal or reversed) and rotation (0o, 60o, 120o, 180o, 240o, 300o) compared to normal (360o was considered as 0o). The measured (or dependant) variable was the reaction time for each of the stimulus orientations and rotations, and was recorded by the computer in milliseconds.

All subjects were initially given a brief verbal introduction to the concept of Mental Rotation, and instructed in the procedure they were about to undergo. They were then told to sit in front of a computer and log on to the Psychology Department LAN, this automatically started the Mental Rotation program. The program was designed to immediately bring up an instruction page on how the stimuli would be presented and how to respond when the stimulus was displayed. The participants’ objective was to respond as quickly and accurately as possible to the stimulus as explained above.

Once the subject was comfortable with the instructions, they were asked to complete 6 practice trials. This allowed the participants the opportunity to familiarise themselves with the experiment, and also meant that fewer data items would be lost to error during the experiment. At the end of the practice trials the subject began the experiment proper. The actual experiment consisted of 144 trials, and was random presentation of all 36 stimuli four times.

Each trial ended when the subject responded to the stimuli (either correctly or incorrectly), or after a delay of 3 seconds. Any mistakes or no response was classed as an error and ignored. The reaction time for each different orientation was recorded in milliseconds, and averaged over the entire experiment, giving 12 values. On completion of subject participation, all data was collected and collated via the LAN. Averages and standard deviations of reaction time were calculated for all participants.


The measured variable for the Mental Rotation experiment was the average reaction time in milliseconds for each orientation (forward or reversed), and rotation (0o, 60o, 120o, 180o, 240o, 300o) for each subject. All subject results were collected and averages were calculated to give the final results. It can be seen in the graphed results that the slope of the plot for the normally presented stimuli is a non-linear function, which supports the hypothesis. However because the plot point at 120o for reversed orientation was faster than expected (926 msec), the resulting plot was not a perfect linear function.

In work done by Koriat and Norman (1985), it can be seen that at the same plot point in their study there was also an anomaly, the point was approximately 50 msec faster than the plot point for 240o, (54o difference in the present experiment). They argued, with the use of significance testing, that this random point was not significant and therefore, the function was linear. Without significance testing it is hard to state whether the point can be ignored in the current example or not. Considering the results achieved by Koriat and Norman (1985), it is tentatively suggested that the function is linear and therefore the hypothesis is supported.

The plot for the normally presented letters followed a clear quadratic function, and compared favourably to Koriat and Norman’s experiment 1., whose data ranged from approximately 500msec at 0o, to approximately 1300msec at 180o (present range 616msec to 1048msec). The reversed data was also similar, but once again, the data in the present testing was within a tighter range (approx. 800msec – 1300msec, compared to 798msec – 1087msec).

The wide range of data for the subjects, as suggested by the high standard deviations indicate that some of the subjects were a lot quicker and some a lot slower than the average reaction time suggests. It is not certain whether this variability had an effect on the results.

To get a more consistent, and therefore accurate set of results, it would be necessary to not only increase the number of subjects, but also increase the number of trials that each subject sat. As there is a strong practise effect associated with the mental rotation task, to keep the subjects from learning the stimuli, it would be important to have more sessions but stagger the testing into smaller blocks of fewer tests, with longer breaks between sessions. Another solution would be to have a novel set of stimuli each time.

There are limited everyday applications for information regarding how humans mentally rotate an object, however mental rotation techniques are used daily, whether it be reading upside down, or doing a jigsaw puzzle. Being able to identify an object in space and rotating it mentally so it can be recognised is critically necessary to human existence. Seldom is an item placed in front of a person in exactly the orientation that they can match it to a mentally stored image. An example would be an apple in a fruit bowl lying on its side. With out being able to rotate a mental projection of the apple to what is regarded as normal orientation, it may never be recognised for what it is and therefore not eaten.

The aim of this experiment was to provide support for previous research into mental rotation, and in particular, the findings of Koriat and Norman (1985). With such strong resemblance between the present experiment and that of Koriat and Norman, not only was the mental rotation phenomenon demonstrated, but also evidence was found to support their broad tuning hypothesis. With regards to the current hypothesis, normal letters did provide a non-linear function, and reversed letters suggested a linear function, which supports with the hypothesis.


Cooper, L. A., & Shepard, R. N. (1973a). The time required to prepare for a rotated stimulus. Memory and Cognition, 1, 246-250

Koriat, A., & Norman, J. (1985). Mental rotation and visual familiarity. Perception & Psychophysics, 37, 429-439

Cohen, D., J.; Blair, C. (1998). Mental rotation and temporal contingencies. Journal of the Experimental Analysis of Behavior. 70 (2), 203-214

Rose, D. J., (1997). A Multilevel Approach to the Study of Motor Control and Learning. Boston: Allyn and Bacon.

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