Mental rotation: how does our mind manage to rotate objects?

The human mind is a very mysterious thingFor 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 tried 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 deal with it. we manage to process and interpret images that are presented to us inverted or rotated and still see them as what we are. Roger Shepard and Jacqueline Metzler considered this in 1971, and they approached it experimentally, conceiving the concept of mental rotation..

Let's see what this idea is all about, and how these researchers delved into it through experimentation in the lab.

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What is mental rotation?

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 if the two figures presented in each trial were identical or if they were the mirror image of each other.

As a result of this experiment, it was seen that there was a positive relationship in terms of the angle in which the figures were presented and the time it took the subjects to answer. The greater the degree of inclination these images presented, 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 more tilt the object has, the longer it will take to mentally rotate it.

Shepard and Metzler, based on all these findings, surmised that the turnover 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.

Legacy and subsequent experimentation

Shepard and Metzler, by means of their already famous experiment, started experiments on mental rotation 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 neural level. In the last two decades, using the evoked brain potential technique, it has been possible to record the brain responses of participants while performing this type of task. It has been observed that mental rotation tasks increase the activity of the parietal regions, which are involved in spatial positioning.

This experiment has been replicated using rotated and inverted letters, hands, numbers, and other symbols to see to what extent subjects they took longer to answer and how knowing the symbol presented influenced the speed at which they answered satisfactorily in the essays.

individual differences

Other investigations have tried to see if there are relationships between gender, age group, race or even sexual orientation and how efficiently mental imagery tasks are performed.

In the 1990s, researchers investigated whether there were differences between men and women in this type of task, given that better visuospatial performance has traditionally been associated with the male gender. It was observed that if explicit instructions were given on how to perform the mental rotation, men had better scores than women, although these differences disappeared if explicit instructions were not given, both genders having the same performance.

Regarding whether there were differences depending on the age group, it was seen that young people presented 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 precision of both age groups did not appear to be very different.

Based on the studies carried out during these years, it is known that the fact of presenting the mirror or identical image also influences the time it takes to respond. The time it takes to decide if the image presented is identical or, on the contrary, if it is the mirror image of the other, is longer when the figure is actually specular.

This is so because, first of all, the person has to rotate it to put it at a proper angle. Then you have to rotate it in the plane to see whether or not it is a mirror image of the other image presented to you. It is this last step that adds time, as long as the images are not the same.

Criticism of Shepard and Metzler

After performing his famous experiment, these two researchers received some criticism regarding the results of their experiment.

In the first place, 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 images could be used mental, and considerable prominence was given to the idea that thought was, almost without exception, the product of language.

Despite this type of criticism, it should be noted that in the original experiment the subjects were not told that they imagined the figure explicitly, they simply resorted to this strategy on their own alone.

Other authors asserted that the fact that it took longer to respond to figures with a higher degree of turnover was not necessarily due to that fact, simply that more saccadic movements were made to make sure they answered correctly.