According to Maslow, the more basic needs have to be satisfied (satisfied according to the needs of our cultural group) before our interest will focus on higher level needs.
However, according to Alderfer, and his ERG (existence, relatedness, and growth needs) theory, (1) more than one need may be operative at the same time, (2) if the satisfaction of a higher level need is frustrated, the desire to satisfy a lower level need increases.