Figure-ground discrimination is one perceptual process.
The transducers, limited as they are, all take in more information than our brains can process.
To keep from being over-laoded, the brain will structure the incoming stimuli into two fields: the figure and the ground.
The figure is the portion of the stimuli that is relevant to our immediate needs. It is strengthened and accentuated in our experience.
The ground is the remaining portion of the stimulus input. It is suppressed in our consciousness.
Hence, a much lesser stimulus array needs to be actually processed by the brain.
When the figure-ground process fails, the end result is a stimulus overload.
The child or adult's brain is bombarded with everything that has been transduced, much of which is irrelevant to our needs.