Our ability to move while perceiving the environment has always been crucial to individual success and our survival as a species
Born to run
Movement is crucial for the survival of all mammals – typically involved in getting to food and escaping from potential danger.
Indeed, according to evolutionary biologists **Dennis Bramble** and **Daniel Lieberman**, our human ancestors evolved to travel long distances by running as long as 2 million years ago, and it “may have been instrumental in the evolution of the human form.”
In fact, **humans perform remarkably well at movement over distance thanks to a diverse set of evolved physiological and psychological adaptations** that may have been key to the survival of the individual, group, and, ultimately, our species.
After all, before the arrival of projectile weapons such as spears, running our prey to exhaustion and collapse, known as **’persistence running,**’ may have been our only reliable way of obtaining a consistent supply of the calories needed to fuel our power-hungry brain.
Being good at movement was not a ‘nice to have’ but a necessity facilitated by body and brain.
Moving through our environments
While a great deal of research has been performed on perception where both subject and object are stationary, the real world is typically one of movement. **Perception does not exist in a context-free, static lab but in complex, noisy environments that change over time** – often very quickly.
Therefore, **research must consider how we process and ultimately respond to a visual environment in constant flux**. After all, we are exceptionally adept at moving successfully within our visual environment and predicting when moving objects will reach us.
Just think of a child’s ability to catch a ball or an adult jumping off a moving escalator, dodging crowds, and rushing to get a train.
And yet, to do so involves several complex concepts, including how we act on the environment and make sense of moving objects – especially people. To do so, we must detect changes occurring in our visual environment over time.
Perceiving the environment
Psychologist and philosopher **James Gibson’s ‘ecological theory of perception’**, described in his book in 1979, was at odds with current views of the time. Rather than simply a process for recognizing objects in the world around us, he argued that **perception was primarily for “keeping in touch with the environment**.”
His theory of ‘**direct perception**’ rejected the idea of mediators, such as mental pictures, getting in the way of ‘information pickup.’
Instead, when creating training films for pilots during the Second World War, he spoke of ‘**optic flow**’ and the changing parts of the visual environment, and the ‘**focus of expansion**,’ where the point to which we move is static while everything else appears to expand away from it.
More recently, research has confirmed that **our attention is drawn to the focus of expansion** as we move forward in a stationary environment, highlighting its psychological importance and value for future research.
Attributing meaning to perception
We may perceive a chair, but what does it take for us to understand its significance? Gibson suggested that **objects have potential, or what he called ‘affordances.’** The chair’s capacity to ‘afford’ sitting is directly perceivable – not causing behavior but making it possible.
Subsequent research tested and appeared to confirm his theory using objects presented so briefly that were not consciously perceived. For example, tool-like images were flashed up, such as a hammer, producing motor priming, while graspable objects, including a razor, reduced reaction time for reaching.
Other theorists have taken on board **Gibson’s ‘ecological’ approach to perception**, recognizing that even mentioning the word ‘hammer’ can begin the activation of motor processes. Yet, we can take it further. **Top-down processing is particularly vital when visual information is limited** and while considering the many other sources of information we use to reach our goals.
And it’s worth noting that Gibson’s idea of ‘affordances’ has been co-opted by interaction designers to refer to the things software and computer systems can allow users to do.
Planning and control
**Any action involves some degree of cognition**. Reaching for a pen, shutting the door, or taking the hand of a loved one all require both planning and control.
**Planning is what mostly happens before the action**. Depending on our goals and the environment, we select the target, decide on the timing, and choose how we should grasp it. The information is then combined with environmental information in the part of the brain known as the ‘**inferior parietal lobe**.’
The control system then kicks in to ensure the movement is performed, constantly adjusting with feedback from our senses – this includes ‘**proprioception**,’ or the awareness of our body position.
Research into patients with brain trauma appears to confirm the independence of the planning and control systems. Indeed, a patient referred with ‘**optic ataxia**’, which is a difficulty in reaching and moving through 3D environments, could reach out to grasp objects. However, **they could not readjust when it was moved during the ‘grasp,’** suggesting damage only to the control system.
Perceiving human motion
Research asking observers to track dots of light on animations of animals moving showed that we are better at detecting and judging ‘human’ motion than of any other species.
Findings suggest that we have specialist areas of the brain that are more sensitive, or ‘tuned,’ to identifying actions that are similar to our own.
**’Transcranial magnetic stimulation’ involves stimulating specific parts of the brain with magnets**, and has been used with willing participants to create temporary ‘lesions’ in the brain, showing harmful interference to the observer’s sensitivity.
The ability to identify physical movements no doubt has evolutionary value. After all, bodily movements are strongly associated with sharing social and emotional information and help promote understanding and better communication.
Identification is particularly high regarding actions related to strong emotions such as fear and anger – especially those influenced by speed. Such movements are usually relatively fast, while fearful or sad individuals move more slowly.
Mirror neurons
Studies using monkeys in the 1990s found that whether they performed a given activity or watched another doing so, some of the same neurons were fired.
This led to the discovery of what has been called **‘mirror neurons,’** which **facilitate learning through the imitation and understanding of others’ actions** and are particularly useful for learning speech.
Neuroimaging studies using humans also found that **brain areas involved in motion perception are the same as those in motion production**. A select few studies have even managed to map down to individual neurons.
And yet, we should be cautious. Observing a concert pianist or a brain surgeon will not convey all the coding required to perform the actions witnessed. And yet, **mirror neurons do seem to provide sufficient information to predict why another is performing the behavior**, which is highly valuable inside and outside our social groups.
The Rubber Hand iIllusion
Awareness of our body and its position is vital to how we interact and move around our environment. And yet, a landmark study in 1998 showed how fragile our perception, awareness, and understanding of our own body actually is.
Described as the ‘**rubber hand illusion**,’ subjects were asked to sit down and place one of their hands to one side, out of sight, behind a barrier. A rubber hand was placed where theirs should have been.
The researcher gently brushed the fake hand and the hidden real one. After a while, they would stop stroking the hidden real hand. Surprisingly, the subjects continued to feel the strokes that they could see happening on the rubber hand.
Such body ownership illusions suggest **our sense of self may not be as coherent as first thought** and that it can extend to non-human objects.
Alien hand syndrome
A 2016 study tested what’s been described as ‘**alien hand syndrome**.’ Subjects reported a sense of ownership over a computer-drawn hand they were operating in a 3D virtual reality environment.
Also, when asked to imagine the movements of the virtual hand, an electroencephalogram (EEG) was still able to record the brain’s electrical activity.
**‘Phantom limb pain’** is similar. Having been through an amputation, patients report experiencing pain in the limb when it’s no longer there.
And the pain is real, often the result of a mix-up of signals between the nervous system and the brain making the body part feel like it’s still there after it’s been removed.
It seems that feedback from vision, touch, position, motion, and our nervous system can be incorrectly combined, changing our sense of ownership, and that thinking of activity can be as real as doing.
