Final answer:
Carl Jung was the neo-Freudian theorist who emphasized the collective unconscious in personality development, proposing that this part of the unconscious contained universal archetypes shared among humans.
Step-by-step explanation:
The neo-Freudian theorist who emphasized the influence of the collective unconscious in personality development was Carl Jung. Jung proposed the concept of a collective unconscious, a part of the unconscious mind that contains memories and ideas believed to be shared among all humans. These are inherited and contain archetypes, universal mental images or themes which can be found across cultures. Jung's theory differed significantly from Freud's original psychoanalytic view, as it extended beyond the personal to include the collective experiences of humanity.