Bottom-up and Top-down Contributors to Pilot Perceptions of Display Clutter in Advanced Flight Deck Technologies

Abstract

Future concepts for the National Airspace System rely on technologies, such as synthetic and enhanced vision systems, to support flight efficiency associated with improved terrain and traffic awareness. While these technologies provide the pilot access to information not available with traditional flight instrumentation, the presentation of this additional information may serve to produce display clutter, thus inhibiting the processes and tasks they are designed to support. An experiment was conducted to assess pilot perceptions and identification of both bottom-up (data-driven) and top-down (knowledge-driven) contributing factors to display clutter. Results revealed the importance of both visual and information density (bottom-up and top-down factors, respectively) to the perception of clutter. Although added display elements provided pilots with critical flight information, pilots considered displays to be cluttered when the imposed visual density exceeded the information density required for specific flight tasks. These findings suggest that moderate levels of display clutter may be tolerable, to the extent that the information is relevant to the tasks at hand.

Display Clutter

“…One of the most cited definitions of this kind is that of Rosenholtz et al (2005), who describe clutter as "the state in which excess items, or their representation or organization, lead to a degradation of performance at some task" (p. 761). Another similar definition is that of Alexander et al (2008), who define clutter as the "unintended effect of displaying visual imagery that may obscure or confuse other information or that may not be relevant to the task at hand" (p. 1180). Specific performance and attentional costs that have been mentioned notably include impaired visual search performance (Moore, Camp, Moyer, & Halford, 2010), which is our focus.…”

“…On the basis of this perspective, clutter can be defined as "unwanted or unnecessary information" (Lohrenz et al, 2009, p. 90), "redundant information" (Ahlstrom, 2005, p. 90), or "an abundance of irrelevant information" (Doyon-Poulin et al, 2012, p. 2D1-2). Alexander et al (2008) emphasized this aspect of clutter in their research by making the distinction between visual density, which is a property of the display and thus related to the density aspect of clutter, and information density, which depends on the context and is related to the task-relevance aspect of clutter.…”

“…Factors that fall under the broad category of display organization include the lack of logical or conceptual grouping of items (Wickens & Carswell, 1995), the absence of symmetry (Oliva, Mack, Shrestha, & Peeper, 2004), the degree to which the target is obscured or masked (Alexander, Stelzer, Kim, & Kaber, 2008;Bravo & Farid, 2004;Chu, Yang, & Li, 2012;Toet, 2010;Xing, 2007), the presence of high entropy (or lack of predictability) within a display (Rosenholtz et al, 2007), and the presence of crowding or the perceptual crowding effect (i.e., the close spacing between a target and the surrounding distractors that slows down visual search (Levi, 2008;Pelli, Palomares, & Majaj, 2004;Tullis, 1983;van den Berg et al, 2009;Vlaskamp & Hooge, 2006). The concept of crowding is also related to the idea of local, as opposed to global, clutter (e.g., Beck, Lohrenz, & Trafton, 2010;Ewing et al, 2006).…”

Review of visual clutter and its effects on pilot performance: A new look at past research

“…Low-clutter displays had only one feature activated (e.g., primary symbology) while high-clutter displays had all features on (primary symbology, HITS, SVS and EVS) [14], [15]. The authors found that medium-clutter displays offer the best technical performance for both glideslope control and localizer stability compared to low-clutter displays.…”

“…Recent works show that pilots perceive clutter as being multidimensional and that both data-driven and knowledge-driven factors contribute to it [14], [15]. These authors found that experienced pilots describe the clutter of a HUD with terms related to both the formatting of the display (e.g., low saliency, high density) and to the usefulness of information shown (e.g., symbol unpredictable or redundant).…”