How did experiments with active and passive kittens show the importance of self-initiated movement?

In the context of perceptual learning, experiments conducted by Richard Held demonstrated that self-initiated movement is essential for the development of normal visually guided behavior.1

In these studies, kittens were paired such that one was allowed to move actively while the other was yoked to its littermate, being pulled passively over the same path. Although both kittens were exposed to identical visual stimuli, the results were starkly different:1

• Active kittens: Developed normal visually guided movements, as their self-initiated actions allowed them to correlate their movements with visual feedback.1
• Passive kittens: Failed to develop normal perceptual functions, indicating that passive visual experience alone is insufficient for the brain to learn how to interpret spatial information correctly.1

This suggests that the process of adaptation and perceptual development relies on the feedback loop created when an observer’s own motor commands are synchronized with the resulting sensory input. Without this active engagement, the brain cannot effectively resolve discrepancies or calibrate its perception of the environment.1