Notice how Justine stretches the 3rd finger from 3rd position up to 4th position and how the hand follows.
The majority of technical shifts involve the whole hand moving as a unit. However just as we sometimes contract the hand, we also can let the finger lead the hand and stretch to a new position. Galamian calls this the retarded shift.
Resources - Bibliography
- for Principles of Violin Playing and Teaching by Galamian, p.25