THE EFFECTS OF VISUAL VARIABLES WITHIN A COMPLEX VISUAL SCENE ON DECISION PROCESSES (HEAD-UP-DISPLAYS, PERCEPTION)

The present research is concerned with the processing of information within a complex visual display. This information processing was examined within the context of an observer shifting attention between displayed sources of information. The two sources of information were an external scene and a Heads-Up Display (HUD) symbology. The experimental tasks used in the current effort were designed to simulate a visual display used in current aircraft flight operations. Specifically the variables of interest included environmental complexity, symbol color, environmental luminance and Stimulus Onset Asynchronous (SOA) times, practice and accommodative distance.;Three experiments were conducted within this research. The first experiment examined a factorial combination of symbol color, environmental luminance and complexity and accommodative distance. The second experiment investigated the relative information acquisition process from a single scene both in the presence and absence of a second component. The third experiment determined the relative efficiency of integrating two information sources as a function of differing SOA values. For all experiments, response latency was the dependent measure.;Results indicated that the factors of accommodative distance and SOA value produced statistically significant differences in performance. Subjects viewing the near distance HUD symbols (1.2m) performed significantly better than subjects viewing the HUD symbols at the far accommodative distance (6m). Increases in SOA values produced corresponding increases in response latency. Practice generally decreased response latency between session halves. There were no main effects for symbol color, environmental luminance or complexity. However, these variables interacted significantly. Luminance interacted with complexity to produce improved responding under low luminance for all environmental complexities and symbol color combinations. Additionally the presence of the environmental scene increased response times to the HUD symbols relative to the background of a homogeneous gray field.;The results of this study are interpreted within the context of the interaction of visual variables and the process of attention. Specifically, this processing is related to the relative ability of the visual variables to segregate the HUD symbols from the background.