Mental Rotation: How Does Our Mind Rotate Objects?
The human mind is a very mysterious thing, for this reason an attempt has been made to discover the mechanisms involved behind its operation. Cognitive psychology has carried out several experiments in which they have sought to elucidate the unknowns behind our thinking.
One of the questions that this branch of psychology has tried to resolve has been how human beings manage to process and interpret images that are presented to us inverted or rotated and still see them for what they are. Roger Shepard and Jacqueline Metzler considered this in 1971, and approached it experimentally, conceiving the concept of mental rotation
Let’s see what this idea is about, and how these researchers delved into it through experimentation in the laboratory.
In 1971, at Stanford University, Shepard and Metzler They carried out an experiment that would catapult them to fame within the field of cognitive sciences In this experiment, participants were presented with pairs of three-dimensional figures with different orientations. The task that the participants had to do was to indicate whether the two figures presented in each trial were identical or if they were mirror images of each other.
As a result of this experiment, it was seen that there was a positive relationship in terms of the angle at which the figures were presented and the time it took the subjects to answer. The greater the degree of inclination of these images, the more difficult it was for them to indicate whether or not the figures were identical.
Based on these results, it was hypothesized that, when images are presented whose angle is not the one usually shown (90º, 120º, 180º…), What we do mentally is rotate the figure until we reach a degree of inclination that is “normal” for us Based on this, the greater the inclination of the object, the longer it will take to mentally rotate it.
Shepard and Metzler, from all these findings, assumed that the rotation process involved going through a series of steps. First, the mental image of the object in question was created. After that, this object was rotated until reaching the inclination that allowed the subsequent comparison and, finally, it was decided whether or not they were two identical objects or not.
Legacy and subsequent experimentation
Shepard and Metzler, through their now famous experiment, initiated mental rotation experiments by investigating different variables. During the 1980s, a new concept arose from the experimentation of these two researchers, the idea of mental imagery This term refers to the ability to mentally manipulate the position of objects, after having made a representation of them in our mind.
Thanks to modern neuroimaging techniques, it has been possible to see how object rotation tasks are affected at the neuronal level. In the last two decades, using the evoked brain potential technique, it has been possible to record the brain responses of participants while they performed this type of tasks. It has been observed that in mental rotation tasks, the activity of the parietal regions, which are involved in spatial positioning, increases.
This experiment has been replicated using rotated and inverted letters, hands, numbers and other symbols to see to what extent the subjects took longer to answer and how knowing the symbol presented influenced the speed at which they responded satisfactorily in the trials.
Individual differences
Other research has tried to see if there are relationships between gender, age group, race or even sexual orientation and how efficiently one performs mental imagery tasks.
In the 90s, it was investigated whether there were differences between men and women in this type of tasks, given that traditionally better visuospatial performance has been associated with the male gender. It was observed that if explicit instructions were given on how to perform mental rotation, men had better scores than women although these differences disappeared if explicit instructions were not given, with both genders having the same performance.
Regarding whether there were differences depending on the age group, It was seen that young people had fewer difficulties than older people when performing this type of task, as long as it was indicated that there was a time limit. In the absence of this limit, the accuracy of both age groups did not appear to be very different.
Based on studies carried out over the years, it is known that presenting the mirror or identical image also influences the time it takes to respond. The time it takes to decide whether the image presented is identical or, on the contrary, if it is the mirror image of the other, is longer when the figure is effectively specular.
This is because, first of all, the person has to rotate it to put it at a proper angle. Then, he has to rotate it in the plane to see whether or not it is a mirror image of the other image presented to him. It is this last step that adds time, as long as the images are not the same.
Criticisms of Shepard and Metzler
After carrying out his famous experiment, These two researchers received some criticism regarding the results of their experiment
Firstly, some authors of the time assured that it was not necessarily necessary to resort to mental images to carry out this type of task. It should be said that in that decade there was some opposition to the idea that mental images could be used, and considerable prominence was given to the idea that thought was, almost without exception, a product of language.
Despite this type of criticism, it should be noted that in the original experiment the subjects were not told to imagine the figure explicitly, they simply resorted to this strategy on their own.
Other authors assured that the fact that it took longer to respond to figures with a greater degree of rotation was not necessarily due to that fact, simply that more saccades were made to make sure they answered correctly
