Introduction
It was Roger Shepard and Jacqueline Metzler (1971) who first presented the concept of mental rotation in cognitive science. This has gained popularity and become one of the renowned studies in the field of cognitive science. Mental rotation is defined as the capability of a person to rotate or turn around mental images that are a resemblance of objects, scenes, or places but are not really present to the senses.
These mental images may be two-dimensional and three-dimensional. It is believed that this activity of mental rotation generally happens in the right cerebral hemisphere. According to several pieces of research, the right cerebral hemisphere functions mainly in perception and recognition of sounds, analysis and interpretation of space that is geometric and visual, body senses or somesthesis, stereognosis, creation of dreams during sleep, and also the perception of music.
The activity of mental rotation is divided into five cognitive stages, namely creating a mental picture of entities, mentally rotating these entities until a correlation can be made, analyzing the comparison, deciding if the entities are identical or not, and lastly is making the decision (Shepard and Metzler, 1971).
Assessment of Mental Rotation Capability
The findings of the research made by Shepard & Metzler (1971) appeared to directly disprove the Behaviorist theory, which holds on the principle that thought processing rely completely upon language by indicating that analogous representations have a considerable role in the thinking process. The ability to mentally rotate an entity is assessed by asking the subject or participant to compare two three-dimensional objects or letters and affirm if they are identical images or if they are enantiomorphs or also known as mirror images (Johnson 1990).
Generally, the test consists of pairs of pictures, each of which is rotated at a certain amount of degrees. There will be pair of images that are identical, but the corresponding pair may be rotated while some pairs will be mirrored. The subject will be given a set of image pairs. The test will judge the accuracy and speed of the subject in comparing and distinguishing paired images that are mirrored and non-mirrored (Johnson, 1990).
In the traditional research of Shepard & Metzler (1971), they showed the participants some pairs of pictures of the three-dimensional, nonsymmetrical collection of cubes. The goal of the experiment was to state immediately whether the pair of images was the same regardless of rotation or as mirror images. The participants answer by pressing a button. Shepard hypothesized that this task would be processed by constructing a three-dimensional mental picture of one of the presented images, and then picturing this image using the imagination and rotating the whole image and visualizing if it could be rotating this whole image, in the imagination, to see whether it could be brought into resemblance with the other image.
The test results supported this hypothesis due to the fact that, for each participant, the time it took for the participants to decide whether the pair of objects is the same increased directly proportional to the difference of the angle of their rotation. After the experiment, participants were given questions on how did they analyze the images, and most of them affirmed that this was how they had processed mentally the objects presented.
In later research in 1982, Shepard and Lynn Cooper illustrated mental rotation in various experimental designs mainly designed to obstruct different analyses of the results that might avoid the postulation of rotating imagery. These experiments did not present two visible images, therefore no scale for Just & Carpenter’s eye movement. Some of these related researches include presenting a rotated alphabet and asking these participants to decide if the letter was a normal or mirror image.
Similarly, the response time increases the further the image is rotated. This would imply that the participants rotate their letters of the non-upright letter in its normal upright position so as to compare it to how the normal letter looks as was stored in their memory. This mental imagery, sometimes termed visualizing, is similar to a perception of the event. However, it occurs without the appropriate external stimuli. Mental imagery is the one responsible for mentally rotating visual objects. Furthermore, it was believed that the axis on which an object is rotated does not count, but rather, it is the angle of rotation that bears the most considerable effect on response time.
So, rotations within the depth plane of two-dimensional objects and rotations in the depth of three-dimensional images behave similarly. Therefore, the matching involves more time as the quantity of depth rotation becomes greater, and similarly for the depth plane (Shepard and Lynn Cooper, 1982). On the other hand, Cooper (1982) also experimented on mental rotation using asymmetrical polygons. He used explicit imagery wherein the experimental result proved a relationship between the reaction time and the degree of rotation, suggesting a regular rotation of an image.
Influence of practice on mental rotation
Studies are also conducted to know whether the practice can influence the response time of a subject in mental rotation. In research on “The influence of long-term practice on mental rotation of 3-D objects” by Leone et al. (1993), the main outcome of the experimental study regarding the effect of long-term practice on mental rotation processing reveals that the speed in mental rotation rate from one session to the next did not rely on either the picture of objects or the imaging ability of the participant.
The initial disparity in the performance of the subjects because of either dissimilarity in the catalogs or deviation in imaging ability continued to be constant over the experimental period. The training on a simpler catalog is more likely to speed up the gaining of mental rotation ability. Furthermore, under the given experimental circumstances with a big set of stimuli and long-term practice, the performance did not result in the loss of process in mental rotation (Leone et al., 1993).
A study by Kail and Park (1990) has a proposition for the general performance which occurs with the practice of mental rotation. For the first test, only a small number of representations are available; therefore, the response times more probably match up to the presentation of the mental rotation algorithm. When practiced, the response time to a stimulus or presented image is recovered straight from memory. Thus, the identification tasks of analyzing the images include both the process of mental rotation and memory retrieval. Moreover, practice affects the process of mental rotation and the acquiring of considerable features as well.
These two factors are engaged concurrently, but the major process, that is, the mental rotation and memory retrieval, as explained by the response times, relies upon the degree of storage of the stimuli. However, the limitation of the theory presumes that mental rotation would vanish with practice. Eventually, the orientation of objects would be stored and then directly recovered from memory. This proposition is hypothetical but gives a rationalization for the independence of response time from Kaushall and Parsons’s (1981) study, which may be accredited to the process of memorization, the Bethell-Fox and Shepard’s (1988) research study that influence one to compensate for the complication.
The result may be due to the presence of recent features, although the algorithm of fairness conclusion is not yet resolved. Generally, the participants rotate objects mentally as a whole. The internal demonstration of some parts of the image belongs to a so-called principal level and not the whole representation of the image. The image of the cubes will be processed separately. Therefore, it can be deduced the as the number of cubes increases, the more features or characteristics one has to maneuver and also to require a greater time amount to implement the mental rotation process (Kail and Park, 1990).
Also, this theory can clarify the outcome of the research study of Yuille and Steiger (1982), which states that the twisted images are processed more gradually than those images that are not twisted. This is due to the fact that for the twisted images, the number of images from the picture’s principal plane was higher when compared to the case of non-twisted images. Therefore, this is the explanation why the speed of processing of mental rotation of these twisted images is more gradual than the speed of the mental rotation process for images that are not twisted.
This experimental study reveals that the participants still use the approach of mental rotation over the long-term practice with a proper quantity of stimuli. The consequence of practice on the process of mental rotation of three-dimensional images effects primarily in an enhancement of rapidity of mental rotation.
To add, the initial deviation in mental rotation processing performances from spatial capabilities of participants or difficulty or degree of complication of three-dimensional images used do not disappear over the experimental period. As predicted, a previous spatial knowledge and practice factor was likely to affect the process of mental rotation where the subjects with great spatial experience acquired higher performance both for precision and rapidity than when compared with those who were not exposed to practice (Yuille and Steiger, 1982).
Moreover, R. Kail (1987) studied the effect of practice on the speed of mental rotation involving children with ages ranging from 9, 13, and 20 years old. They were tested on 3840 tests of a mental rotation processing wherein they had to decide if the presented pairs of images, which are in different rotations, were the same or just mirror objects. It was found out that response time rises linearly as a function of the disparity in the orientation of the object, and the angularity of this function was applied to approximate the speed of mental rotation. The study revealed that at all ages included in the experiment, mental rotation became faster over trials.
Age differences in the rate of mental rotation were eliminated after approximately 1500 trials. At all ages, the influence of practice was well characterized by hyperbolic and power functions. Furthermore, children’s and adolescents’ data were well fit by hyperbolic and power functions in which most of the parameters of those functions were constrained to adults’ values. These results are discussed in terms of possible mechanisms underlying the impact of practice (Kail, R. 1987).
A related study by R. Kail and Y. S. Park (1990) on the effect of practice on the speed of mental rotation included a test involving 11- and 20-year-old children and adolescents on 3360 tests of a mental rotation performance wherein they determined whether the letters presented in different degree of rotations are identical or mirror images. The study showed that children’s and adults’ mental processing times decreased significantly over the practice.
These changes were well defined by hyperbolic and power functions wherein, for the most part of the parameters of those functions were bound to adults’ values. Presentation on two transfer tests, mental rotation of letter-like images and memory exploration for numbers, demonstrated that the practiced skill or ability did not simplify to other concerns of domains (R. Kail and Y. S. Park, 1990).
Training spatial skills
According to a study performed by Wright, R. et al. (2008), spatial alteration abilities are an important characteristic of cognitive capacity. These abilities can be enhanced by practice, though these practices are specific to tests and stimuli.
The experiment tested whether thorough long-term practice effects of changing that surpass stimulus and test circumstances. Thirty-one subjects were tested on three cognitive trials: a version of the Shepard-Metzler (1971) using computers: a mental rotation test, a mental paper-folding test, and a verbal analogies test. Each participant attends the daily practice for 21 days. Post practice correlation manifested of practice gains to stimuli for the practiced test and transferred to the other no practiced test, as well. Therefore, practice results were based on process, not based on occurrence (Wright, R. et al., 2008).
Conclusion
The study of Roger Shepard and Jacqueline Metzler (1971) revealed that the reaction time for subject participants to conclude if the pair of items are identical or not was linearly proportional to the degree of rotation from the image’s original position or arrangement. That means that the more the image is rotated, the longer the subject can determine whether the pair of images presented are the same or just mirror images.
However, despite the facts gathered in this experimental research, some researchers doubted the role of mental rotation. For instance, the works of Just and Carpenter argued that response time does not come from the mental rotation of the object but from the eye movements made between the two images while comparing these objects (Shepard and Metzler, 1971). Furthermore, based on the proposed theory of Kail and park (1990), practice heightens the strength and the number of representations of a given image that is saved in memory (Kail and Park, 1990).
References
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Johnson A.M. (1990). Speed of mental rotation as a function of problem solving strategies. Perceptual and Motor Skills, 71, 803-806.
Kail, R. (1987). “The impact of extended practice on rate of mental rotation” Journal of experimental child psychology. 198701; 42(3):378-91. ISSN: 0022-0965.
Kail, R. and Park, Y.S., (1990). Impact of practice on speed of mental rotation,.I. Exp. Child Psychol., 49 227-244.
Kaushall, P. and Parsons, L.M., (1981). Optical information and practice in the discrimination of 3D mirror-reflected objects, Perception, 10 545-562.
Leone, G. et al, (1993). “The influence of long term practice on mental rotation of 3-D objects.”
Shepard, R and Metzler. J. (1971). “Mental rotation of three dimensional objects.” Science. 171(972):701-3.
Shepard, R and Cooper, L. (1982). “Mental images and their transformations.” Cambridge, MA: MIT Press.
Wright, R. et al (2008). “Training generalized spatial skills.” Psychon Bull Rev. 15(4):763-71.
Yuille, J.C. and Steiger, J.H., (1982). Nonholistic processing in mental rotation: some suggestive evidence, Percept. Psychophys., 31 201-209.