Experience-Expectant Plasticity describes the normal, generalized development of neuron connections that occur as a result of common experiences that all humans are exposed to in a normal environment. These early universal experiences are visual stimulation, sound (specifically voices), and bodily movement.
The brain has been developed through evolution to 'expect' these early stimulating experiences and uses them to activate particular synapses that are involved in senses like vision and hearing. If everything is normal then the brain will develop in an expected fashion. But if something has happened that inhibits the perception of these experiences then development can be stunted or halted altogether.
An example of this is when vision is obstructed in an infant and they are unable to perceive the expected visual information the brain needs to form the synapses necessary to the proper functioning of the visual system. Although the infant started out with the required synapses to be able to see they were pruned away because the brain failed to perceive the visual stimulation.