Visual perception of infrared imagery

The visual threshold criteria for the psychophysical tasks of identification (ID) and identification friend or foe (1FF) for use with infrared imaging systems are presented, including the previously unused approach of signal detection theory (SDT) for determining visual thresholds for the Johnson task of identification. The results are also interpreted using the standard high-threshold theory methods and the two methods are compared. The original task of identification friend or foe is presented and compared to the standard identification task. The experiment presented used a much larger set of stimuli than other reported contemporary experiments and the effects of set size are discussed.