Cockpit design flawed? Research may give instrumentation displays a new look

The study by Dr. Greg Davis of Cambridge University in the U.K. challenges previous scientific consensus-and suggests that changing displaysso they flicker, using one color and containing more objects will better stimulate visual reactions in pilots than conventional multicolored outline displays.

The potential advantages for new types of display arise because our conscious, visual perception of the environment is quite restricted. The retina in the human eye can register literally thousands of pieces of information simultaneously. But, the process by which the brain processes this information to isolate a limited number of important factors is complex. It has consequences for the design of many critical machineman interfaces, from fighter pilot cockpits to vehicle dashboards and virtual gaming environments.

Although the human eye can code many object images simultaneously, we are only aware of a tiny fraction of this information. The "visual" brain has evolved to prioritize relevant features in a scene and ignore irrelevant ones. But this selectivity can lead to problems in information-rich environments as, for example, when driving a car or landing an aircraft. In some cases, vision can fail to cope and accidents result. Examples include "looked but failed to see" accidents in which sober drivers run into highly visible, stationary police cars in broad daylight.

To reduce the incidence of these events, a large amount of research in psychophysics and ergonomics has examined how display qualities affect our ability to simultaneously process multiple features in the visual environment.

Many experiments have found that combining several features into one displayed object can optimize human performance. Combining a number of pieces of information in a single object appears to improve reaction times and visual memory compared to separating the information in two or more objects. However, recent experiments have shown that in many cases exactly the opposite is true. The design of previous experiments was flawed, effectively eliminating one important visual processing pathway in the brain.

The new research by Cambridge's Davis shows that information sources can be more efficiently processed when they belong to separate objects. Contrary to conclusions from previous work, reducing the number of objects in a display appears to have no general effect on perceptual performance. The findings have important implications for a diverse range of display technologies including those in cockpits, car dashboards, and virtual environment situations.

Davis' research suggests there are two separate pathways that process different visual information. The brain uses one pathway called the parvocellularventral processing stream to process "within-object" relationships between shapes, colors, and textures of the same object. In contrast, new research indicates that "between-object" information — relationships between features from separate, neighboring objects — are processed via a second pathway called the magnocellular-dorsal processing stream.

Cells in the parvocellular-ventral pathway show long-lived responses to objects in the visual field and play a major role in our recognition of objects. However, the magnocellular-dorsal process is implicated in the visual guidance of action. This is the mechanism by which we judge distances between objects and allows us to accurately reach out and grab objects.

All previous experimental approaches of this type have only fully stimulated the parvocellular-ventral pathway, while ignoring or under stimulating the magnocellular-dorsal process. This has led to results that show improved performance for single object, multifeature displays. By reassessing the experimental design to equally stimulate the two pathways, multiobject displays often result in better performance.

Results indicate that stimulation of the magnocellular-dorsal process significantly enhances performance for multiobject displays. The magnocellulardorsal process is most readily activated by flickering displays and is sensitive even to low contrast, monochromatic objects. In contrast, many current displays are nonflickering colored and are constructed from thin outline symbols. These primarily activate the parvocellularventral pathway and do not yield the same performance benefits as displays that activate the magnocellulardorsal pathway.