Answer: Dishabituation
Step-by-step explanation:
Dishabituation is when you start reacting to old stimuli when there is something new with stimuli.
For example, if you became habitual with loud sound you may notice it when the loudness of sound changes. That's why Ambulance has variable sound loudness in its siren.
The same case is with baby, when we saw him a new picture he notices it and pauses the sucking of a pacifier.