Protocol Analysis for X-ray Threat Detection Screeners

X-ray images provide information about the inner structure of the object and depict density, whereas photographs created by light reflection provide information about an object’s surface. Thus, X-ray screeners rely on a very different set of perceptual cues and strategies to recognize objects and potential threats. Also, the X-ray detection task is typically conducted in an environment with a high degree of uncertainty. The goals of the current study were to capture the cues, techniques and strategies that: 1) were associated with correct identification of threats, 2) resulted in threat identification rather than detecting cues that an image had been artificially inserted, and 3) clearly distinguished the cues, techniques and strategies of expert performers from those of lower performing individuals. [1] demonstrated that protocol analysis was highly effective in task domains that involved predominantly visualization and spatial manipulation skills. [2] indicated that the complexity of the Transportation Security Officer visual search task requires a knowledge elicitation technique to be conducted in situ. Training content was developed to optimize the transfer of expert knowledge to new hires. The success of the protocol analysis technique for this purpose is expected to be validated through an ongoing training effectiveness evaluation.