How do babies connect seeing and doing?
Infants who experienced a stronger real-time connection between their own movements and what they saw on screen showed greater brain activation when watching those movements.
Source
Baby steps: investigating the development of perceptual-motor couplings in infancy
What they did
To study how infants connect visual and motor experiences, researchers assigned 31 infants aged 7 to 9 months to one of three training conditions. In the Contingent group (10 infants), babies stepped on an infant treadmill while viewing real-time video of their own legs. In the Non-contingent group (10 infants), babies stepped while watching pre-recorded video of another infant stepping, and a Visual control group (11 infants) did not step at all. EEG was used to measure sensorimotor cortex activity before and after two daily training sessions while the infants watched videos of others stepping.
What they found
Across all three groups, infants showed a general increase in sensorimotor alpha suppression at the post-test compared to the pre-test. There were no significant overall differences between the three treatment groups at post-test. However, within the Contingent group, infants who experienced a stronger real-time visual connection (contingency) to their own movements showed significantly greater alpha suppression at post-test, while motor movement on its own did not predict this brain activity.
The limits
What it doesn't show
The study does not show strong group-level differences, which may be due to the small sample size of 10 or 11 infants per group, limiting the statistical power. Additionally, the high exclusion rate of 39 infants (54% of those tested) raises potential generalizability issues. Lastly, because treadmill-elicited stepping is a partially reflexive behavior, it is not completely certain to what extent this task engages the voluntary motor cortex in infants around 8 months of age.
Key terms
- perceptual-motor couplings
- Neural connections that allow the brain to link the visual perception of an action with the motor commands used to perform it.
- sensorimotor alpha suppression
- A reduction in alpha-wave brain activity over the sensorimotor cortex that indicates the region is actively processing movement or observation.
- associative learning
- A process where the brain links two different events or stimuli because they repeatedly happen together in time.
- contingency
- The statistical likelihood that one event, like seeing a leg move, reliably occurs at the same time as another, like physically stepping.
- treadmill-elicited stepping
- An automatic, walking-like response triggered in young, pre-walking infants when they are held over a moving treadmill.
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Quiz yourself
What core hypothesis regarding mirror neurons (perceptual-motor couplings) did this study test?
Common questions
Why did the infants wear a skirt during training?
The infants wore a tutu-like skirt to block them from looking directly down at their own legs, ensuring that any visual experience of their movements came only from the screen in front of them.
Did simply taking more steps on the treadmill lead to stronger brain connections?
No, the researchers found that the sheer number of steps (motor experience) did not predict brain activity; instead, only the tight visual-motor coordination predicted stronger neural connections.
Why wasn't there a clear difference between the Contingent and Non-contingent groups?
Unlike studies in adults with visual-motor coordination around 100% and hundreds of trials, the infants in the Contingent group only experienced an average coordination of 59% over a limited number of trials, which likely reduced the overall group differences.
Why did all infants show an increase in brain activity at post-test?
The authors suggest that repeatedly watching the stepping videos might have helped infants learn to predict the movements, or triggered pre-existing neural connections linked to seeing leg movements.
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