Dennis B. Beringer

Target Size, Location, Sampling Point and Instructional Set: More Effects on Touch Panel Operation

Accuracy of input using touch panel devices is affected by a number of variables which include device type, target size, and target location. It was also hypothesized that instructional set should influence performance. A screening experiment using a central-composite design (CCD) was conducted to further examine the effects of target position and size upon accuracy of the touch input. Results suggest that error for right-handed users is least near the resting position of the hand (lower right corner of display) and that shortest response times could also be obtained there. Variations in size were more likely to affect error in the y axis and quadratic effects were present. It was also found that although instructions requiring higher precision of input from the operator did not substantially affect bias error, they did produce a reduction in variable error. It is recommended that for applications having established key input areas, positions along the lower and right-hand borders of the control/display unit should be used to minimize activation time and error. Use of the lower border exclusively can accomodate users with either a right-hand or left-hand preference. Some comments are also provided on the limitations which bound the interpretation of results in several studies and inferences thus drawn.

Operator Behavioral Biases Using High-Resolution Touch Input Devices

Real-world applications of touch-input technology often do not occur under ideal conditions. Users often must contend with off-axis viewing and nonoptimal positioning, introducing the possibility of vertical or horizontal bias error. In the present study the effects of screen angle relative to line of sight and positioning of targets were examined with a high-resolution (1 pixel or about 1/12 mm) resistive touch input device thought to have minimal parallax. Results replicated earlier findings of Beringer & Peterson (1985) in that a 17-degree declination of the touch surface below orthogonal to line of sight induced a high-touch bias error of 9 pixels (about 3/4 mm) whereas orthogonality of the interface to line of sight virtually eliminated bias. Both software and behavioral compensation strategies are discussed.

Touch Panel Sampling Strategies and Keypad Performance Comparisons

A study was conducted to improve accuracy of touch input devices to be used in helicopter evnironments through serial sampling and minima selection algorithms. Neither first nor last contact point was congruent with point of minimum error and sampling techniques were derived to reduce error without using “touch-mouse” strategies, being most effective for the infrared panel. Wearing flight gloves and using the nonpreferred hand had no practical detrimental effects on performance for a high-resolution touch input task. In a second study several types of mechanical keypads were compared with the two types of touch-input devices. Results obtained with this menu-selection task suggested no practical degradation in performance when substituting the touch input devices for bezel-mounted hardware keys. This was true of both error rate (in a qualified sense) and response time. It was concluded that the touch-input devices could provide flexibility for high-resolution input using maps and other spatial forms of data while allowing effective use of previously developed menus and menu-selection routines without the need for auxiliary bezel-mounted mechanical keys.

Peripheral integrated status display

Abstract Much effort has been directed towards the creation of effective integrated displays for vehicle or system control. These efforts have generally been aimed at ‘primary’ instruments or indices of system performance, and only comparatively recently have secondary indices received similar attention. Each group of indices, however, has generally been kept separate, resulting in systems having multiple nonintegrated integrated displays. A method is proposed whereby these may be combined within a single instrument or ‘integrated’ integrated display. This method is based on the use of spatial cues created by regular versus irregular polygons. A major question at issue is whether such a display constitutes a single integrated shape or merely an assembly of subshapes that are serially scanned.

Putting Information in the Visual Periphery: It Beats a Pointed Stick in the Eye

The Increasing complexity of systems has placed great pressure on the system designer to provide effective and efficient means for communicating system and subsystem status information to the operator. The conventional means of providing this feedback ultimately require displays beyond those required for momentary control of the system, increasing the amount of visual information that must be processed and usually increasing the amount of instrumentation present. It may be possible to integrate these secondary sources of Information within the context of a single display that Is proximal to primary system displays and has strong spatial pattern characteristics. Three formats of such a “peripheral” display were examined in the context of a simulated instrument flight task. The “figural” displays appeared to provide a slight edge in performance over a histogram-based display.

Educating Engineering Psychologists: Are we “Going around in Academic Circles”?*

In 1972 Hunt, Howell, and Roscoe examined and compared the goals of various educational programs for engineering psychologists. Two years later Martin considered “What is wrong with human factors students?” The present treatise is an attempt to discover whether we are operating in a closed universe and have in fact come round to our starting point or have progressed in our attempts to equip students for gainful employment. Comparisons are drawn between the state of the educational process then and its present condition, including data on basic skills (NAEP, Spring 1989) and higher-level thinking abilities (anecdotal and empirical) or lack thereof. Contemporary problems are outlined and sources of these difficulties are identified where possible. Problem areas include deficiencies in student preparation, academic and industrial short-term corporate memory, supply-demand communication, economic forces, and the issue of certification (individuals and programs). The authors conclude by examining where current trends may be taking us.

Control/Response Compatibility, Muscle Synergy and the Virtual Visual Field: What you See is What you Get

Three components were hypothesized which could affect operator response in the manual control of a system. These included muscle synergy compatibility (MS), geographic control/display compatibility (CD), and visual-field compatibility (VF). Disruption in one of these was suspected as a contributing factor in documented accident cases. A 2χ2χ2 between-subjects factorial design was used to evaluate all combinations of compatible and incompatible arrangements based upon these variables, using 64 undergraduate students as participants. A static-target acquisition task was used in which subjects manipulated a specially designed joystick to move a cursor to defined target locations. Performance measures included reaction time, movement time, homing time, and frequency and magnitude of directional reversals. Results indicated that visual field (VF) compatibility/incompatibility significantly influenced reaction time, homing time, and reversal frequency and magnitude, while CD and MS manipulations had no significant main effects on performance. Significant gender effects were also found. The results of this study suggest that compatibility of control input and system response is judged primarily by direction of movement in the virtual visual field (self reference). This has implications for the design of systems such as small mobile cranes where the operator may be repositioned relative to a fixed directional control.

PERCEIVED AUTOMOBILE SAFETY AS A FUNCTION OF BODY STYLE, COSMETIC DESIGN VARIATION, AND VIEWING DISTANCE

Some of the noticeable external variations in the appearance of vehicle systems are direct reflections of structural differences while others are more “cosmetic” in nature. It was hypothesized that judgements of vehicle safety, although often a function of structural design and operator personal experience, may be influenced by essentially cosmetic external variations in design that do not represent salient differences in vehicle structure. Individuals were asked to rate the general and specific safety characteristics of automobiles from viewing a series of photographs of each of several body styles. The general safety rank orderings, obtained in two separate samples, were expected, placing sedans and station wagons safest with convertibles least safe. Those cars initially ranked as less safe than average exhibited further reductions in average rated safety as viewing distance decreased. Rated likelihood of injury increased, on average, as viewing distance decreased. Rated likelihood of rollover ejection was affected by whether occupant would or would not be wearing a seat belt and did not interact with body style, which also influenced the ratings. Models that were structurally equivalent were rated differently depending upon whether removable roof panels were installed or removed. It appears that the presence of some removable sections or accessories may actually decrease the operators perception of the hazard present although the actual hazard may not have been decreased.