Your brain’s ability to instantly link what you see with what you do is down to a dedicated information ‘highway’, suggests new UCL-led research.
For the first time, researchers from UCL and Cambridge University have found
evidence of a specialised mechanism for spatial self-awareness that combines
visual cues with body motion.
Standard visual processing is prone to distractions, as it requires us to
pay attention to objects of interest and filter out others. The new study has
shown that our brains have separate ‘hard-wired’ systems to visually track our
own bodies, even if we are not paying attention to them. In fact, the newly-discovered
network triggers reactions even before the conscious brain has time to process
The researchers discovered the new mechanism by testing 52 healthy adults
in a series of three experiments. In all experiments, participants used robotic
arms to control cursors on two-dimensional displays, where cursor motion was
directly linked to hand movement. Their eyes were kept fixed on a mark at the
centre of the screen, confirmed with eye tracking.
In the first experiment, participants controlled two separate cursors
with their left and right hands, both equally close to the centre. The goal was
to guide each cursor to a corresponding target at the top of the screen.
Occasionally the cursor or target on one side would jump left or right,
requiring participants to take corrective action. Each jump was ‘cued’ with a
flash on one side, but this was random so did not always correspond to the side
about to change.
Unsurprisingly, people reacted faster to target jumps when their
attention was drawn to the ‘correct’ side by the cue. However, reactions to
cursor jumps were fast regardless of cuing, suggesting that a separate
mechanism independent of attention is responsible for tracking our own
This [the results] provides strong evidence for a dedicated neural pathway linking motor control to visual information, independently of the standard visual systems that are dependent on attention.
Dr Alexandra Reichenbach (UCL Institute of Cognitive Neuroscience)
“The first experiment showed us that we react very quickly to changes relating to objects
directly under our own control, even when we are not paying attention to them,”
explains Dr Alexandra Reichenbach (UCL Institute of Cognitive
Neuroscience), lead author of the study. “This provides strong evidence for a
dedicated neural pathway linking motor control to visual information,
independently of the standard visual systems that are dependent on attention.”
The second experiment was similar to the first, but also introduced
changes in brightness to demonstrate the attention effect on the visual
perception system. In the third experiment, participants had to guide one cursor
to its target in the presence of up to four dummy targets and cursors,
‘distractors’, alongside the real ones. In this experiment, responses to cursor
jumps were less affected by distractors than responses to target jumps.
Reactions to cursor jumps remained vigorous with one or two distractors, but
were significantly decreased when there were four.
“These results provide further evidence of a dedicated ‘visuomotor
binding’ mechanism that is less prone to distractions than standard visual
processing,’ says Dr Reichenbach. “It looks like the specialised system has a
higher tolerance for distractions, but in the end it is still affected. Exactly
why we evolved a separate mechanism remains to be seen, but the need to react
rapidly to different visual cues about ourselves and the environment may have
been enough to necessitate a specialised pathway.”
The newly-discovered system could explain why some schizophrenia patients
feel like their actions are controlled by someone else.
“Schizophrenia often manifests as delusion of control, and a dysfunction
in the visuomotor mechanism identified in this study might be a cause for this
symptom,” explains Dr Reichenbach. “If someone does not automatically link corresponding
visual cues with body motion, then they might have the feeling that they are not
controlling their movements. We would need further research to confirm this,
and it would be fascinating to see how schizophrenia patients perform in these
These findings could also explain why people with even the most advanced prosthetic
limbs can have trouble coordinating movements.
“People often describe their prosthetic limbs as feeling ‘other’, not a
true extension of their body,’ says Dr Reichenbach. “Even on the best
prosthetic hands, if the observed movement of the fingers is not exactly what
you would expect, then it will not feel like you are in direct control. These
small details might have a big effect on how people perceive prostheses.”
- Active brain via Shutterstock