Fear is bigger motivator than need
In my opinion depending on level of satisfaction or deprivation, one mentally attaches a score to needs or fears at different levels. The scores are less for the lower needs in Maslow's hierarchy and go up with higher needs. The scores for fears run counter to this. A loss of self actualisation will have lower negative score than say a loss of physical need. A sum of wn(i) * N(i) - wf(i) * f(i) actually gives the factor which influences a person.
In the equation wn(i) stands for weighing factor for need (i)
N(i) for Need(i)
Wf(i) for weighing factor for fear (i) and
f(i) for fear (i)
The factors depend on where a person stands on satisfaction level for that particular need.