Is habituation responsible for inaccurate airport security screenings? The U.S. Transportation Security Administration has "red teams" who try to sneak dangerous items through airport security.  The security personnel often fail up to 95% of these tests. Is this high failure rate to be expected because of habituation to visual stimulus?  Specifically, a screening agent is expected to find a single weapon amidst thousands of X-rays without a weapon.

If this is habituation, are there techniques for reducing its impact in scenarios such as this?
The main reason for these failures is mental fatigue and lost of concentration, in conjuction with the weak target signals.


  Vigilance decrement is defined as "deterioration in the ability to
  remain vigilant for critical signals with time, as indicated by a
  decline in the rate of the correct detection of signals". Vigilance
  decrement is most commonly associated with monitoring to detect a weak
  target signal. Detection performance loss is less likely to occur in
  cases where the target signal exhibits a high saliency. ... Under most
  conditions, vigilance decrement becomes significant within the first
  15 minutes of attention, but a decline in detection performance can
  occur more quickly if the task demand conditions are high ... More recent studies 
  indicate that vigilance is hard work, requiring the allocation of
  significant cognitive resources, and inducing significant levels of
  stress.


Habituation plays very little role in these failures.


  Early theories of vigilance explained the reduction of
  electrophysiological activity over time associated with the vigilance
  decrement as a result of neural habituation. ... More recent ERP
  studies indicate that when performance declines during a vigilance
  task, N100 amplitude was not diminished. These results indicate that
  vigilance is not the result of boredom or a reduction in neurological
  sensitivity


Training and motivation can decrease failures.


  Training and practice significantly reduce the vigilance decrement,
  reduce the false alarm rate, and may improve sensitivity for many
  sustained attention tasks. Training improvements may also occur due to
  the reduced mental workload associated with task automaticity. In
  pilotage and airport security screening experiments, trained or expert
  subjects exhibit better detection of low salience targets, a reduction
  in false alarms, improved sensitivity, and a significantly reduced
  vigilance decrement. In some cases the vigilance decrement was
  eliminated or not apparent.