Monday, 31 July 2023
Visualization and mental imagery
The process of mental imagery was first demonstrated in experiments such as those by Shepard and Metzler , in the early 1970s, in which the subjects had to decide whether 3D images of arrangements of cubes matched a physical model. To complicate this task, the images in question had been rotated in space. The researchers soon realized that the more the images had been rotated, the longer it took for the subjects to determine whether or not they matched the model, which meant that the subjects were turning the cubes “in their heads” to see whether there was a match.
The results of these experiments in mental chronometry disproved the then prevailing belief that our mental representations eventually become completely independent of the sensory modalities from which we derived them. Subsequently, it was demonstrated that similarly, our mental representations of actions produce brain-activation patterns very similar to the ones produced when we are actually preparing to take the same actions in the physical world.
One of the first indications that mental imagery might potentially be used to train people in performing motor sequences came from an experiment conducted by Australian psychologist Alan Richardson in the 1960s. He divided his subjects randomly into three groups, had them take 100 shots on a basketball net, and assessed their performance. Then he asked one of these groups to practice shooting baskets for 20 minutes per day, another to do nothing at all, and the third to simply visualize taking successful shots for 20 minutes per day while also imagining the weight of the ball, the sound that it would make when they dribbled before shooting it, and so on. Three weeks later, he had each group shoot baskets and assessed their performance again. Not surprisingly, the group that had done nothing showed no improvement at all. But quite surprisingly, the group that had performed the visualization task had improved almost as much as the group that had actually practiced shooting baskets for 20 minutes per day. These results show that simply activating the brain’s sensorimotor networks “offline” improves their connectivity, so that later on, when someone performs the action in question for real, their motor control will be more precise and their movements more effective. More recent studies not only have confirmed that we can in fact refine our movements without moving, but have also shown that combining real training with mental visualization provides an even greater benefit.
Placing all of these studies in the context of the broader history of cognitive science, and in particular of the studies by Lawrence Barsalou in the 1990s, we can say that scientists’ explanation of mental simulation has evolved from one that is highly representational to one that is more sensorimotor. From the 1960s through the 1990s, our mental categories and concepts were thought to come from abstract representations involving arbitrary symbols such as words that, once learned, no longer engaged the sensory areas of the brain, which were seen as separate modules. But subsequently, this idea of what Barsalou called amodal representations (high-level symbolic activations in the brain, completely separate from its sensorimotor areas) had been superceded by a far more “modal” vision of how things work, in which the slightest mental simulation activates the primary and secondary cortexes of the various sensory modalities. And after numerous fMRI experiments, it has now become commonly accepted that mental imagery requires the activation of sensorimotor areas associated with the object being simulated mentally. For example, when you imagine a cup, the activation of the neurons in the premotor areas for your hand increases, because you hold a cup with your hand. Similarly, for obvious regions, if you imagine a soccer ball, the increased activation will occur in the motor areas associated with your legs and feet.
Body Movement and the Brain, From Thought to Language | Comments Closed
