Abstract
Mental rotation is a spatial task that involves the ability to mentally retain an object and rotate it in space. The purpose of this experiment was to replicate that of previously published studies like that of Shaperd and colleague to obtain the typical mental rotation effect. The independent variable in this experiment was the degree of rotation and the dependent variable was the response time. Participants were 14 male and 22 female undergraduate students who attended Douglas College, who were recruited from a 2nd year introductory cognitive psychology course. The task was to determine, as quickly as possible, whether two shapes, one of which was rotated to a certain degree relative to the orientation of the other shape, were the same or different. There was a minimum of 70 trials. For each pair of "same" and "different" stimuli, five trials were presented for each rotation angle. Only response times for which the participants were correct were used. The curve for the same shape stimuli is nearly a straight line except for the final degree of rotation. The curve for different shapes varied consistently with changes in rotation. The results of this study demonstrated the hypothesis that reaction time will increase as the angle of rotation increases. It demonstrates that people can mentally rotate images and it takes more time to react when the degrees of rotation increase.

Mental Rotation Effect Mental rotation is a spatial task that involves the ability to mentally retain an object and rotate it in space. This ability is important for academic achievement given its supposed ability to predict success in topics such as geometry, mathematics, chemistry and physics; and for everyday spatial activities, such as orientation in unfamiliar places or finding a route on a map (Moe, 2008). Mental rotation usually takes place in the right cerebral hemisphere, in the areas where perception also occurs. It is associated with the rate of spatial processing and intelligence Roger Shepard and his colleagues (1971) designed one of the most often-used tasks. The Mental Rotation Task. In this task subjects were shown two novel visual stimuli and were asked to determine whether the stimuli had the same shape or different (mirror image) shapes. The shapes (random block shapes) were rotated around the vertical axis. Subjects reported that they mentally rotated a shape in their head until the two stimuli were oriented the same way, and then made their judgement. The results of the experiment confirmed the original hypothesis. The time it took for each subject to identify if two objects were identical was directly proportional to the angular rotational difference between them. The greater the angular rotational difference, the greater the time it took to identify the similarity (Shepard & Metzler, 1971). What was important about this experiment was that it was one of the first to apply quantitative methods to the study of imagery and to suggest that imagery and perception may share the same mechanisms. Mental imagery is a quasi-perceptual experience in the absence of sensory input whereas visual imagery is actually "seeing" in the absence of a visual stimuli. (Prime, 2014). Sex is another variable to consider in an analysis. Prior research has revealed that rotation times are faster for men than for women (Heil & Jansen-Osmann, 2008). Gender differences in the Mental Rotations Test are larger than in virtually all other spatial tests and have been highly robust over decades. Several possible explanations for this phenomenon have been proposed. The research done by Glück and Fabrizii (2010) tests the hypothesis that the gender differences are partly due to the response format of the MRT. This format, in combination with the high time pressure of the MRT, may be particularly conducive to the performance of highly confident (i.e., frequently male) participants who use “quick-and-dirty” response strategies. In study of 288 students, a new MRT version was used in which a variable number of 0 to 4 alternatives per item were correct. Gender differences were significantly smaller than in the standard MRT. In particular, the performance of highly confident male participants was markedly lower than in the standard MRT. Although practice leads to improved rotation performance for both men and women, practice does not eliminate the sex difference in rotation speed (Terlicki, Newcombe, & Little, 2007). In addition, based on the idea that attention is drawn to a novel object, Moore and Johnson (2008) used a habituation technique to gather evidence supporting inferences about sex differences in mental rotation among infants as young as 5 months; boys were more capable of distinguishing between objects and their mirror images than were girls.
Method
Participants Participants were 14 male and 22 female undergraduate students who attended Douglas College. Six participants were left handed and 30 participants were right handed.
Procedure
Participants for this experiment were students who were recruited from a 2nd year introductory cognitive psychology course. 36 students participated in this experiment. This experiment replicated that of Shepard and his colleagues (1971) who designed the mental rotation task. Students sat at monitors and logged on to their Coglab account to access the experiment. The viewing distance, distance from eye to fixation point on monitor, was approximately 85 centimeters. The angular size of stimuli was approximately seven degrees of visual angle. For the location of stimuli, each shape was centered approximately 10 degrees to the left or right of the fixation. Once students logged on they saw a rectangle on their screen were the trials were taken place. On each trial, a fixation point was shown and than disappeared. Then, two 3-D block shapes appeared on the screen, one to the left and one to the right. Each block shape was within a circle. The two shapes were either identical, or different (one was a mirror image of the other). One shape was also rotated around the vertical axis. The rotation was 0, 20, 40, 60, 80, 100, or 120 degrees relative to the orientation of the other shape. The task was to determine, as quickly as possible, whether the two shapes were the same or different. There was a minimum of 70 trials. Feedback was given after every trial on whether their response was correct. For each pair of "same" and "different" stimuli, five trials were presented for each rotation angle. If a mistake was made (e.g. say the stimuli were different when they were actually the same), the trial was repeated (with different stimuli) later in the experiment. This way only response times for which the participants were correct were used. Participants were instructed that if they found themselves often making mistakes, to try slowing down on their response or to try harder. Participants used a computer during this experiment and pressed the n-key to start the trial, then moved their right index finger over to the m-key. When the two 3D block shapes were the same, participants pressed the z-key with their left index finger as fast as they could. If they thought the two 3D block shapes were different, they pressed the m-key with their right index finger as fast as they could. The independent variable in this experiment was the degree of rotation. The dependent variable was the response time.
Results
This experiment allowed us to participate in the mental rotation task showing that the reaction time will increase as the angle of rotation increases. Mean Response Times for each condition were calculated by first calculating the mean across trials for each subject and then averaging these means across subjects. As expected, participants response time increased as the amount of rotation also increased (see Appendix). For a zero degree rotation angle, mean RT was 1743ms for same shape objects and 2840ms for different shape objects. For a 20 degree rotation angle, mean RT was 2050ms for same shape objects and 2946ms for different shape objects. For a 40 degree rotation angle, mean RT was 2414ms for the same shape objects and 2858ms for different shape objects. For a 60 degree rotation angle, mean RT was 2578ms for same shape objects and 2940ms for different shape objects. For an 80 degree rotation angle, the mean RT was 2872ms for same shape objects and 2926ms for different shape objects. For a 100 degree rotation angle, the mean RT was 2914ms for same shape objects and 2834ms for different shape objects. For a 120 degree rotation angle, the mean reaction time was 2808ms for same shape objects and 2963ms for different shape objects. The curve for the same shape stimuli is nearly a straight line except for the final degree of rotation. The curve for different shapes varied consistently with changes in rotation.
Discussion
The results of this study demonstrated the hypothesis that reaction time will increase as the angle of rotation increases. It demonstrates that people can mentally rotate images. It takes more time to react when the degrees of rotation increase. When Shepard and Metzler measured participants reaction time to decide whether pairs of objects were the same or different, they obtained the results like those in Figure 1 (See Appendix). When two shapes were separated by an orientation of 40 degrees, it took two seconds to decide that a pair was the same shape, but for a difference of 140 degrees, it took four seconds. Showing that reaction times were longer for greater differences in orientation (Goldstein, 2011). Shepard allows that the time may depend on the familiarity of the shape. He found that when two identical threedimensional shapes in different orientations are projected in succession on the eye, the observer unwillingly sees a continuous rotation of the shape from one orientation to the other, and that the time for rotation through a unit angle is much less than when a mental image of a shape is knowingly rotated. Shepard found also that complexity does not affect rotation time. Although the hypothesis in the study was supported there are some methodology problems in this experiment design. First, the block-shape 3D images are hard to identify even one at a time for some people and the test only takes correct answer into consideration. The repetition of the tests may cause fatigue to some subjects and the correct answers can be generated by random clicking of images. Second, the block-shape objects are not something that we can encounter in the real life so the subjects may have to take extra effort to analyze the images. Finally, the correct answer can be derived by ways other than mental rotation. For example, you can simply just find a starting point of the block-shape images and ‘walk through’ the images to see if the two images have the same route. Recent research (e.g., Cherney, 2008) has provided additional evidence that playing computer games, particularly with massed practice, can improve mental rotation skills, with improvements in women's scores being most notable after practice with a computer game that involved a race within a 3-D environment. Beyond rotation skills, mental representations of physical objects can facilitate problem solving. For example, Hegarty (2004) demonstrated that people manipulate mental representations to make inferences about mechanical problems, such as how gears or pulleys operate. Similarly, Schwartz and Black (1999) found that engaging in mental simulations of actions such as pouring water enhances people's ability to answer questions about the amount of tilt required for containers of different heights and widths. The curve for the same shape stimuli in our results is nearly a straight line except for the final degree of rotation. The curve for different shapes varied consistently with changes in rotation. In conclusion studies have found rotation times are faster for men than for women but with practice, one can improve their mental rotation skills. Although practice leads to improved rotation performance for both men and women, practice does not eliminate the sex difference in rotation speed. Shepard concluded that imagery and perception may share the same mechanisms and that the time differences may depend on the familiarity of the shape. The results from our experiment similarly match those done by Shepard and colleagues finding that reaction time will increase as the angle of rotation increases. It demonstrates that people can mentally rotate images showing that reaction times were longer for greater differences in orientation.

References
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Glück, J., Fabrizii, C. (2010). Gender differences in the mental rotations test are partly explained by response format. Individual Differences, 31(2), 106-109. doi: 10.1027/1614- 0001/a000019

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Heil, M., & Jansen-Osmann, P. (2008). Sex differences in mental rotation with polygons of different complexity: Do men utilize holistic processes whereas women prefer piecemeal ones? The Quarterly Journal of Experimental Psychology, 61, 683-689. Moe, A. (2008). Are Males better then Females in Mental Rotation. Science Direct, 19, 21-27. Reteived from: www.elsevier.com/locate/lindif

Prime, D. J., (2014). Lab 2: Imagery: Mental Rotation [PowerPoint Slides]. Retrieved from https://learn.douglas.bc.ca/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=%2 Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id%3D_205

Prime, D.J., (2014). Lecture 10: Visual Imagery [PowerPoint Slides]. Retrieved from https://learn.douglas.bc.ca/webapps/portal/frameset.jsp?tab_tab_group_id=_2_1&url=%2 Fwebapps%2Fblackboard%2Fexecute%2Flauncher%3Ftype%3DCourse%26id%3D_205

Shepard, R. N., Metzler, J. (1971). Mental Rotation of Three-Dimensional Objects. Science, New Series, 171(3972), 701-703. Retrieved from: http://www.jstor.org/stable/1731476

Schwartz, D. L., & Black, T. (1999). Inferences through imagined actions: Knowing by simulated doing. Journal of Experimental Psychology: Learning, Memory, & Cognition, 25, 116-136.

Terlecki, M. S., Newcombe, N. S., & Little, M. (2008). Durable and generalized effects of spatial experience on mental rotation: Gender differences in growth patterns. Applied Cognitive Psychology, 22, 996-1013.

Appendix

Mental Rotation Experiment

Figure 1. Mean response times to same shape and different shape rotated objects.