Mental rotation is the ability to rotate mental representations of two-dimensional and three-dimensional objects as it is related to the visual representation of such rotation within the human mind. There is a relationship between areas of the brain associated with perception and mental rotation. There could also be a relationship between the cognitive rate of spatial processing, general intelligence and mental rotation.
Mental rotation can be described as the brain moving objects in order to help understand what they are and where they belong. Mental rotation has been studied to try to figure out how the mind recognizes objects in their environment. Researchers generally call such objects stimuli. Mental rotation is one cognitive function for the person to figure out what the altered object is.
Mental rotation can be separated into the following cognitive stages: Create a mental image of an object from all directions (imagining where it continues straight vs. turns). Rotate the object mentally until a comparison can be made (orientating the stimulus to other figure). Make the comparison. Decide if the objects are the same or not. Report the decision (reaction time is recorded when a lever is pulled or a button is pressed).
Assessment Originally developed in 1978 by Vandenberg and KuseVandenberg, S., & Kuse, A. (1978). Mental Rotation, a Group Test of Three-Dimensional Spatial Visualization. Perceptual and Motor Skills, 47, 599-604. based on the research by Shepard and Metzler (1971), a Mental Rotation Test (MRT) consists of a participant comparing two 3D objects (or letters), often rotated in some axis, and states if they are the same or if they are mirror images (enantiomorphs). Commonly, the test will have pairs of images each rotated a specific number of degrees (e.g. 0°, 60°, 120° or 180°). A set number of pairs will be split between being the same image rotated, while others are mirrored. The researcher judges the participant on how accurately and rapidly they can distinguish between the mirrored and non-mirrored pairs.
Notable research
Shepard and Metzler (1971)
Roger Shepard and Jacqueline Metzler (1971) were some of the first to research the phenomenon.Shepard, R. N., & Metzler, J., "Mental rotation: Effects of Dimensionality of Objects and Type of Task", Journal of Experimental Psychology: Human Perception and Performance, Vol 14, Feb 1988, pp. 3-11. Their experiment specifically tested mental rotation on three-dimensional objects. Each subject was presented with multiple pairs of three-dimensional, asymmetrical lined or cubed objects. The experiment was designed to measure how long it would take each subject to determine whether the pair of objects were indeed the same object or two different objects. Their research showed that the reaction time for participants to decide if the pair of items matched or not was linearly proportional to the angle of rotation from the original position. That is, the more an object has been rotated from the original, the longer it takes an individual to determine if the two images are of the same object or enantiomorphs.
Vandenberg and Kuse (1978)
In 1978, Steven G. Vandenberg and Allan R. Kuse developed the Mental Rotations Test (MRT) to assess mental rotation abilities that was based on Shepard and Metzler's (1971) original study. The Mental Rotations Test was constructed using India ink drawings. Each stimulus was a two-dimensional image of a three-dimensional object drawn by a computer. The image was then displayed on an oscilloscope. Each image was then shown at different orientations rotated around the vertical axis. The original test contained 20 items, demanding the comparison of four figures with a criterion figure, with two of them being correct. Following the basic ideas of Shepard and Metzler's experiment, this study found a significant difference in the mental rotation scores between men and women, with men performing better. Correlations with other measures showed strong association with tests of spatial visualization and no association with verbal ability.
Neuropsychology In 2000, a study was conducted to find out which part of the brain is activated during mental rotation. Seven volunteers (four males and three females) between the ages of twenty-nine to sixty-six participated in this experiment. For the study, the subjects were shown eight characters 4 times each (twice in normal orientation and twice reversed) and the subjects had to decide if the character was in its normal configuration or if it was the mirror image. During this task, a PET scan was performed and revealed activation in the right posterior parietal lobe.
Functional magnetic resonance imaging (fMRI) studies of brain activation during mental rotation reveal consistent increased activation of the parietal lobe, specifically the inter-parietal sulcus, that is dependent on the difficulty of the task. In general, the larger the angle of rotation, the more brain activity associated with the task. This increased brain activation is accompanied by longer times to complete the rotation task and higher error rates. Researchers have argued that the increased brain activation, increased time, and increased error rates indicate that task difficulty is proportional to the angle of rotation.
A 2006 study observed the following brain areas to be activated during mental rotation as compared to baseline: bilateral medial temporal gyrus, left medial occipital gyrus, bilateral superior occipital gyrus, bilateral superior parietal lobe, and left inferior occipital gyrus during the rotation task.Halari, R., Sharma, T., Hines, M., Andrew, C., Simmons, A., & Kumari, V. (2006). Comparable fMRI activity with differential behavioural performance on mental rotation and overt verbal fluency tasks in healthy men and women. Experimental Brain Research, 169(1), 1–14.
Development Gloria Marmor was the first to study mental rotation abilities in children. These and a number of subsequent studies suggested that children can solve mental rotation task that require a forced choice by the age of about 3.5 to 5 years, although at a slower speed than adults, and that mental rotation performance is linked to motor activity. In contrast, research measuring infants' looking times has shown that they can already track and anticipate the orientation of objects in the first year of life, and discriminate mirrored objects that differ in orientation.
A study from 2008 further suggested that sex differences may occur early during development. The experiment was done on 3- to 4-month-old infants using a 2D mental rotation task. They used a preference apparatus that consists of observing during how much time the infant is looking at the stimulus. They started by familiarizing the participants with the number "1" and its rotations. Then they showed them a picture of a "1" rotated and its mirror image. It appears that gendered differences may appear early in development, as the study showed that males are more responsive to the mirror image. According to the study, this may mean that males and females process mental rotation differently even as infants. However, other infant studies did not find any sex differences. Supporting the presence of sex differences early in development, other studies have found that gendered differences in mental rotation tests were visible in all age groups, including young children. Interestingly, these differences emerged much later for other categories of spatial tests.
In 2020, Advances in Child Development and Behavior published a review that examined mental rotation abilities during very early development.Moore, D. S. & Johnson, S. P. (2020). The development of mental rotation ability across the first year after birth. In Advances in Child Development and Behavior (Vol. 58, pp. 1–33). essay, Science Direct. The authors concluded that an ability to mentally rotate objects can be detected in infants as young as 3 months of age. Also, MR processes in infancy likely remain stable over time into adulthood. Additional variables that appeared to influence infants' MR performance include motor activity, stimulus complexity, hormone levels, and parental attitudes
Factors that affect performance
Color Physical objects that people imagine rotating in everyday life have many properties, such as textures, shapes, and colors. A study at the University of California Santa Barbara was conducted to specifically test the extent to which visual information, such as color, is represented during mental rotation. This study used several methods such as reaction time studies, verbal protocol analysis, and eye tracking. In the initial reaction time experiments, those with poor rotational ability were affected by the colors of the image, whereas those with good rotational ability were not. Overall, those with poor ability were faster and more accurate identifying images that were consistently colored. The verbal protocol analysis showed that the subjects with low spatial ability mentioned color in their mental rotation tasks more often than participants with high spatial ability. One thing that can be shown through this experiment is that those with higher rotational ability will be less likely to represent color in their mental rotation. Poor rotators will be more likely to represent color in their mental rotation using piecemeal strategies (Khooshabeh & Hegarty, 2008).
Athletic, musical, and artistic skills Research on how athleticism and artistic ability affect mental rotation has been conducted. Pietsch, S., & Jansen, P. (2012) showed that people who were athletes or musicians had faster reaction times than people who were not. They tested this by splitting people from the age of 18 and higher into three groups. The groups consisted of music students, sports students, and education students. It was found that students who were focused on sports or music did much better than those who were education majors. Also, it was found that the male athletes and education majors in the experiment were faster than the respective females, but male and female musicians showed no significant difference in reaction time.
A 2007 study supported the results that musicians perform better on mental rotation tasks than non-musicians. In particular, orchestral musicians' MRT task performance exhibited aptitude levels significantly higher than the population baseline.Sluming, V., Brooks, J., Howard, M., Downes, J. J., & Roberts, N. (2007). Broca's area supports enhanced visuospatial cognition in orchestral musicians. The Journal of Neuroscience, 27(14), 3799–3806.
Moreau, D., Clerc, et al. (2012) also investigated if athletes were more spatially aware than non-athletes. This experiment took undergraduate college students and tested them with the mental rotation test before any sport training, and then again afterward. The participants were trained in two different sports to see if this would help their spatial awareness. It was found that the participants did better on the mental rotation test after they had trained in the sports, than they did before the training. This experiment brought to the research that if people could find ways to train their mental rotation skills they could perform better in high context activities with greater ease.
Researchers studied the difference in mental rotation ability between gymnasts, handball, and soccer players with both in-depth and in-plane rotations. Results suggested that athletes were better at performing mental rotation tasks that were more closely related to their sport of expertise.
There is a correlation in mental rotation and motor ability in children, and this connection is especially strong in boys ages 7–8. The study showed that there is considerable overlap between spatial reasoning and athletic ability, even among young children.