Towards an Understanding of the Effect of Night Vision Display Imagery on Scene Recognition

Abstract

An experimental study was carried out to evaluate the combined effect of the absence of colour and the alteration of surface intensities on the recognition of complex scenes. This approach was motivated by the properties of the monochrome imagery of night vision goggles (NVGs), which are a commonly used form of night vision display. Observers were presented with pairs of aerial views of simulated urban scenes (from 400 or 700 ft), taken from viewing angles that differed by 30 deg to ensure that participants could not rely on a viewpoint-dependent cognitive representation of the scene. The observer's task was to decide whether the two scenes were the same, apart from the rotated viewpoint. On catch trials, which were fewer in number, one of the scenes was also mirror reversed. These trials were included to prevent guessing or premature responses. On half the trials, one of the scenes was rendered to simulate the effects of night-vision imagery. The time taken for the observers to confirm the identity of the rotated scenes was measured. There was no effect of differing altitude. When both of the scenes were rendered as daylight imagery, the average time to achieve a match was 34.7 s. When one of the scenes was rendered as NVD-style imagery, the matching time rose to 50.8 s. This effect varied according to the complexity of the scene and the extent to which the scene contained salient coloured features. There were also pronounced differences between observers. These findings suggest that night vision displays may have adverse effects on scene recognition compared to viewing natural-coloured images of the same scenes.