Leo Gugerty

Reference-Frame Misalignment and Cardinal Direction Judgments: Group Differences and Strategies.

In 3 experiments, the authors examined how misalignment of egocentric and exocentric reference frames affects cardinal direction judgments. Experiments 1 and 2 demonstrated large differences in the accuracy and speed with which 104 less experienced and 7 experienced navigators made cardinal direction judgments. Reference-frame misalignment was associated with large performance decrements. The extent of these decrements diminished as ability and experience increased: however, even experienced navigators showed decrements when reference frames were misaligned. In Experiment 3, the authors used 55 college students to examine the individual subtasks of a common strategy for cardinal direction judgments and to isolate the effects of reference-frame misalignment to a particular subtask of this strategy. The tasks and strategies studied in this article can be applied in the development of navigational training and interfaces.

Debugging by skilled and novice programmers

Two experiments investigated expert-novice differences in debugging computer programs. Debugging was done on programs provided to the subject, and were run on a microcomputer. The programs were in LOGO in Exp. 1 and Pascal in Exp. 2. Experts debugged more quickly and accurately, largely because they generated high quality hypotheses on the basis of less study of the code than novices. Further, novices frequently added bugs to the program during the course of trying to find the original one. At least for these simple programs, experts superior debugging performance seemed to be due primarily to their superior ability to comprehend the program.

Effects of Brief Training on Use of Automated External Defibrillators by People Without Medical Expertise

Objective: This study examined the effect of three types of brief training on the use of automatic external defibrillators (AEDs) by 43 lay users. Background: Because AEDs were recently approved for home use, brief training for nonprofessional users needs investigation. Method: During training, the exposure training group read an article about AEDs that provided no information on how to operate them; the low-training group inspected the AED and read the operating instructions in the paper-based manual but was not allowed to use the device; and the high-training group watched a training video and performed a mock resuscitation using the AED but no manikin. All participants returned 2 weeks later and performed a surprise simulatedAED resuscitation on a manikin. Results: Most participants in each training group met criteria of minimally acceptable performance during the simulated manikin resuscitation, as measured by time to first shock, pad placement accuracy, and safety check performance. All participants who committed errors were able to successfully recover from them to complete the resuscitation. Compared with exposure training, the low and high training had a beneficial effect on time to first shock and errors. Conclusion: Untrained users were able to adequately use this AED, demonstrating walk-up-and-use usability, but additional brief training improved user performance. Application: This study demonstrated the importance of providing high-quality but brief training for home AED users. In conjunction with other findings, the current study helps demonstrate the need for well-designed training for consumer medical devices.

Evidence from a partial report task for forgetting in dynamic spatial memory

G. Sperling (1960) and others have investigated memory for briefly presented stimuli by using a partial versus whole report technique in which participants sometimes reported part of a stimulus array and sometimes reported all of it. For simple, static stimulus displays, the partial report technique showed that participants could recall most of the information in the stimulus array but that this information faded quickly when participants engaged in whole report recall. An experiment was conducted that applied the partial report method to a task involving complex displays of moving objects. In the experiment, 26 participants viewed cars in a low-fidelity driving simulator and then reported the locations of some or all of the cars in each scene. A statistically significant advantage was found for the partial report trials. This finding suggests that detailed spatial location information was forgotten from dynamic spatial memory over the 14 s that it took participants to recall whole report trials. The experiment results suggest better ways of measuring situation awareness. Partial report recall techniques may give a more accurate measure of peoples momentary situation awareness than whole report techniques. Potential applications of this research include simulator-based measures of situation awareness ability that can be part of inexpensive test batteries to select people for real-time tasks (e.g., in a driver licensing battery) and to identify people who need additional training.

Development of a Novel Measure of Situation Awareness: The Case for Eye Movement Analysis:

Situation awareness (SA) is a measure of an individuals knowledge and understanding of the current and expected future states of a situation. While there are numerous options for SA measurement, none are currently suitable in dynamic, uncontrolled environments. The current research explored the relationship between direct measures of SA and eye tracking measures as a first step in the development of an unobtrusive measure to be used in environments not suited for existing SA measurement methods. Results showed that the more individuals fixated on an important aircraft in an air traffic control task, the higher their SA for that aircraft. The study also provided evidence that the way operators allocate attention (i.e., distributed widely or narrowly) affects their SA, as well as their task performance. The results indicate that eye tracking may be a viable option for measuring SA in environments not conducive to current direct SA measurement techniques.

Effects of Electronic Map Displays and Individual Differences in Ability on Navigation Performance

Objective: The aim of this study was to determine how strongly the performance of navigation tasks is affected by changing electronic map interfaces and by individual differences in spatial ability. Background: Electronic map interfaces have two common configurations, north up and track up. Research suggests that north-up maps benefit some navigational tasks and track-up maps benefit others. However, little research has investigated how map configuration affects the important navigation task of judging cardinal direction or how individual differences in spatial ability interact with map configuration in affecting navigation performance. Method: In an aerial reconnaissance task, 16 participants completed route-following, cardinal direction, and map reconstruction tasks. Participants also completed three spatial ability tests. Results: The track-up map led to better performance on the cardinal direction and route-following tasks. The north-up map led to better performance on the map reconstruction task. Effects of map configuration showed small to medium effect sizes. Spatial ability correlated positively with performance of each navigation task, showing medium to large effect sizes. For some tasks, a helpful map interface compensated for low ability. For other tasks, ability facilitated the performance of the helpful interface; optimal performance required a helpful interface and high ability. Conclusion: Achieving high performance at particular navigation subtasks requires two things: using the map configuration that optimizes subtask performance and having high spatial ability. Application: Some aspects of navigation performance can be improved primarily by using the optimal map configuration; other aspects require using the optimal configuration and having better spatial ability.

Judgment accuracy in pair-distance estimation and map sketching

Intersite distances were obtained using both subjective pair-distance judgments and map sketching, either perceptually with the map in view or from memory following a study period. The perceptual distance estimates were more accurate than those made from memory. In addition, when responses were made from memory, intersite distances on the sketched map were more accurate than the same distances estimated in the pair judgment task.

A Cognitive Model of Strategies for Cardinal Direction Judgments

ABSTRACT Previous research has identified a variety of strategies used by novice and experienced navigators in making cardinal direction judgments (Gugerty, Brooks, & Treadaway, 2004). We developed an ACT-R cognitive model of some of these strategies that instantiated a number of concepts from research in spatial cognition, including a visual-short-term-memory buffer overlaid on a perceptual buffer, an egocentric reference frame in visual-short-term-memory, storage of categorical spatial information in visual-short-term-memory, and rotation of a mental compass in visual-short-term-memory. Response times predicted by the model fit well with the data of two groups, college students (N = 20) trained and practiced in the modeled strategies, and jet pilots (N = 4) with no strategy training. Thus, the cognitive model seems to provide an accurate description of important strategies for cardinal direction judgments. Additionally, it demonstrates how theoretical constructs in spatial cognition can be applied to a complex, realistic navigation task.

The effects of subpixel addressing on users' performance and preferences during reading-related tasks

Subpixel addressing is a font-rendering technology that triples the apparent horizontal resolution of liquid crystal displays. Four experiments measured the effects of subpixel addressing (Microsofts ClearType) relative to standard (aliased) font-rendering techniques. Participants preferred, and gave higher readability ratings to, text that had been rendered using subpixel addressing. Subpixel addressing also significantly improved the accuracy of lexical decisions and the accuracy and speed of sentence comprehension. Subpixel addressing did not affect word-naming performance or reading speed during pleasure reading. Taken together, these findings suggest that subpixel addressing provides substantial benefits to users while adding no costs to display hardware.

The use of analytical models in human-computer-interface design

Abstract Researchers in the human-computer interaction field have advocated that interface designers use analytical models of the user (e.g. the GOMS model) to help them consider user needs during the design process. This paper surveys the literature on analytical models for interface designers, focusing initially on empirical studies of the validity of these models. This survey shows that analytical models can by used by interface designers in two ways: (1) as task analytic tools that help in generating preliminary design ideas, and (2) as tools for evaluating preliminary designs by predicting user performance and satisfaction. Empirical studies have demonstrated that analytical models can be used in the task analysis phase of design; in these studies, models were successfully used to generate new designs for existing interfaces, with the new designs leading to improved user performance. Regarding the use of analytical models to evaluate interface designs, a number of empirical studies have shown that these models can help explain the factors affecting user performance in a precise, quantitative fashion. However, these explanations have only been given for existing interfaces. Advocates of analytical models have not yet demonstrated convincingly that models can generate accurate a priori predictions of user performance for a new interface. This kind of prediction is necessary before analytical models can be used effectively by interface designers. The final section of the paper focuses on the practical constraints affecting the use of analytical models in interface design organizations, such as organizational schedules, budgets and training requirements. In this section, suggestions are made concerning research needed before analytical models can be used in real-world design projects.