|1. Tests of significance of differences||67%||(155 papers)|
|2. Correlation||10%||(22 papers)|
|3. Frequency, percentage||24%||(56 papers)|
|4. None||5%||(12 papers)|
would be even greater if one included such tests as multiple regression, discriminant analysis, or factor analysis in this category. Although the categories in this content area tend to overlap, the relatively large number of studies in which the analysis stopped at frequency and percentage should be noted.
What does this review tell us about the nature of aviation HF research? The large number of topic areas, both general and specific, ranging from information processing to geographical orientation to electroencephalography to pilot attitudes (to note only a few topics taken at random), indicates that many areas are being mined, but very few intensively. The major concerns are basic research as it relates to flight and displays. In spite of the fact that presumably automation (the "glass cockpit"), situational analysis, and workload are all "hot" topics in the aviation research community, they receive only a modest degree of attention. If one adds up all the topics that deal with sophisticated mental processes (e.g., decision making, mental models, cognition) and add to these crew coordination, a fair bit of attention is being paid to higher order behavioral functions. This represents some change from earlier research areas.
Most of the behavioral research in aviation is conducted on the ground, for which there are obvious reasons: nonavailability of aircraft and cost of flights. Another reason is perhaps that much of the research deals with cockpit or display variables, which may not require actual flight. Reliance on opinion expressed in questionnaires and on incident/accident reports and on full-scale simulators diminishes the need to measure in actual flight. It may also reflect the fact that behavioral research in general (not only in aviation) rarely takes place in the operational environment, which is not conducive to sophisticated experimental designs and instrumentation. This leaves us, however, with the question of whether results achieved on the ground (even with a high degree of simulation) are actually valid for flight conditions. The problem is compounded by the fact that a third of all subjects employed in these studies were not flying personnel.
HF research in aviation is not completely wedded to an experimental format; only half the studies reported were of this type. It is remarkable that with a system whose technology is so advanced, there is so much reliance on nonexperimental techniques and subjective data.
What this review of the aviation HF literature suggests is that research in the future should endeavor to concentrate on key issues to a greater extent than in the past. "Broad but shallow" is not a phrase one would wish to describe that research in general. One of the key issues in aviation HF research (as it should be in general behavioral research as well) is that of the effects of automation on human performance. It seems inevitable that technological sophistication will increase in the coming century and that