Clutter can slow visual search. However, experts may develop attention strategies that alleviate the effects of clutter on search performance. In the current study we examined the effects of global and local clutter on visual search performance and attention strategies. Pilots and undergraduates searched for an elevation marker in charts of high, medium, and low global clutter. The target was in a low or high local clutter region of the chart or it was absent. High global and local clutter slowed search performance for both pilots and undergraduates. Pilots were more accurate but slower. Pilots' search strategies differed from undergraduates in the following ways: they had more conservative criteria for responding target absent and spent more time processing the information within each fixation. Pilots and undergraduates used a coarseto-fine search strategy in which, as the trial progressed, fixation durations increased and saccade distance decreased.

Clutter can slow visual search. However, experts may develop attention strategies that alleviate the effects of clutter on search performance. In the current study we examined the effects of global and local clutter on visual search performance and attention strategies. Pilots and undergraduates searched for an elevation marker in charts of high, medium, and low global clutter. The target was in a low or high local clutter region of the chart or it was absent. High global and local clutter slowed search performance for both pilots and undergraduates. Pilots were more accurate but slower. Pilots' search strategies differed from undergraduates in the following ways: they had more conservative criteria for responding target absent and spent more time processing the information within each fixation. Pilots and undergraduates used a coarseto-fine search strategy in which, as the trial progressed, fixation durations increased and saccade distance decreased.

No abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and revievi/ing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information The Naval Research Laboratoty (NRL) has tested and demonstrated a prototype moving-map system for naval landing craft and amphibious vehicles. NRL proposed that a moving-map would improve crew situational awareness and communications, thereby improving precise lane navigability. This paper presents results of demonstrations performed during the Transparent Hunter naval exercise in January 2003. Comparisons in navigation performance (measured in terms of root mean square "cross-track" error) are presented for vehicles using the moving-map system and the same vehicles using no moving-map. These results suggest that the moving-map significantly improves lane navigation perfomiance. Crew feedback was also positive: crewmembers reported that the moving-map was easy to operate with minimal training and very effective in helping operators keep the vehicle within the lane.

Vector-based maps are an advanced capability of digital moving-map systems that are easily customised and can be powerful aids to aircrew information processing and decisionmaking. However, they may place excessive demands on an aircrew's information processing requirements, cause an increase in workload, and degrade situational awareness if the user interface is not designed properly. There is little information available about the human factors and situational awareness issues relevant to vector-based maps. In this paper, we summarise relevant research on human factors and situational awareness aspects of using vector-based maps, identify key issues, and recommend directions for future research. KEY WORDS1. Maps\Charts.2. Human Factors. 3. Situational Awareness.1. INTRODUCTION. Aircraft digital moving-map systems are designed to provide useful information for navigation and tactical tasks and to allow the aircrew to focus their attention on performing these tasks with a minimum amount of headdown time. When properly designed, digital moving-maps should display information more efficiently than paper maps such that aircrew can obtain all the information required to assess a situation and accomplish a task with a quick glance. Digital moving-map systems should also provide the aircrew with the ability to access and control the displayed information selectively (Rogers and Spiker, 1988 ;Unger and Schopper, 1995). Vector-based maps, which are an advanced capability of digital moving-map systems, differ from conventional raster-scanned maps in that they are rendered from individually stored objects, including points with associated symbols (e.g., airports), linear features (e.g., roads), and areas (e.g., shaded cities) (Willis and Goodson, 1997). These point, linear, and area features are often arranged in multiple data layers (or libraries) organised and interrelated via a relational or object-oriented database structure. The features are stored using identification codes in related groups (classes) and displayed via bitmapped symbology. They are selectable by major or minor classes so permitting a display to be customised. For these reasons, vector-based maps and map overlays have the potential to be powerful aids to aircrew information processing and decision-making. However, they may place excessive demands on an aircrew's information processing requirements, increase workload, and degrade situational awareness if the user interface is not designed properly. Unfortunately,