A Field Study Assessing Driving Performance, Visual Attention, Heart Rate and Subjective Ratings in Response to Two Types of Cognitive Workload

In an on-road experiment, driving performance, visual attention, heart rate and subjective ratings of workload were evaluated in response to a working memory (n-back) and a visual-spatial (clock) task. Subjective workload ratings for the two types of tasks did not statistically differ, suggesting a similar level of overall workload. Gaze concentration and heart rate showed significant changes relative to single task driving during the extra tasks and the magnitude of change was similar for both, while driving performance measures were not sensitive to the increase in workload. The results suggest high sensitivity of both gaze dispersion and heart rate as measures of workload across these two different types of cognitive demand

The Incredible Shrinking Letter: How Font Size Affects the Legibility of Text Viewed in Brief Glances

As in-vehicle interfaces have become miniature computers with userfacing LCD screens, the complexities of designing for them have increased tremendously. Given their safety-critical nature, designers must carefully consider every aspect of the vehicle’s digital interface. Recent research has suggested that even the typeface used to display the interface’s text can have significant impacts on driver behaviors such as total off-road glance time and secondary task completion time. Here we outline a psychophysical method for rapidly assessing the glance-based legibility of two different typefaces (a “humanist” and a “square grotesque”) presented in two different sizes (3mm and 4mm). Consistent with previous research, we find that humanist type is more legible than square grotesque. We also find that text is empirically less legible at 3mm compared to 4mm, and that this effect is especially pronounced for the square grotesque typeface. Legibility thresholds were also found to increase linearly with age, more than doubling across the age range studied. We hypothesize that the square grotesque’s intrinsic design characteristics cause it to scale poorly at small sizes and lose important details, especially in suboptimal display conditions

A Secondary Assessment of the Impact of Voice Interface Turn Delays on Driver Attention and Arousal in Field Conditions

Voice interface use has become increasingly popular in vehicles. It is important that these systems divert drivers’ attention from the primary driving task as little as possible, and numerous efforts have been devoted to categorizing demands associated with these systems. Nonetheless, there is still much to be learned about how various implementation characteristics impact attention. This study presents a secondary analysis of the delay time between when users finish giving commands and when the system responds. It considers data collected on 4 different production vehicle voice interfaces and a mounted smartphone in field driving. Collapsing across systems, drivers showed an initial increase in heart rate, skin conductance level, and off-road glance time while waiting for a system to respond; a gradual decrease followed as delays continued. The observed attentional and arousal changes are likely due to an increase in anticipation following a speech command, followed by a general disengagement from the interface as delay times increase. Safety concerns associated with extended delay times and suggestion of an optimal range for system response times are highlighted

Assessing the impact of typeface design in a text-rich automotive user interface

Text-rich driver–vehicle interfaces are increasingly common in new vehicles, yet the effects of different typeface characteristics on task performance in this brief off-road based glance context remains sparsely examined. Subjects completed menu selection tasks while in a driving simulator. Menu text was set either in a ‘humanist’ or ‘square grotesque’ typeface. Among men, use of the humanist typeface resulted in a 10.6% reduction in total glance time as compared to the square grotesque typeface. Total response time and number of glances showed similar reductions. The impact of typeface was either more modest or not apparent for women. Error rates for both males and females were 3.1% lower for the humanist typeface. This research suggests that optimised typefaces may mitigate some interface demands. Future work will need to assess whether other typeface characteristics can be optimised to further reduce demand, improve legibility, increase usability and help meet new governmental distraction guidelines

The effects of performance feedback and their implications for the time course and stabilization of perceptual learning

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Visual perceptual learning (VPL) is defined as a long-term performance improvement on a visual task due to repeated exposure or training. Behavioral factors such as feedback (knowledge of performance accuracy) can strongly influence VPL, but remain sparsely studied. Here a series of experiments is presented in which subjects were trained to detect two coherent motion directions over 7 days. One of the two directions was consistently paired with feedback and the other was not. Results show that feedback can augment the performance benefits accrued for its paired stimuli while simultaneously inhibiting VPL of unpaired stimuli. The psychophysical data strongly suggest that feedback may exert its benefits by facilitating the long-term consolidation and stabilization of VPL, thus making VPL robust against interference from the presentation of new, novel stimuli. These results highlight an "inferential gap" intrinsic to these types of investigations: traditional measures of performance accuracy are coarse, and the gulf between an observer's percept and the chosen performance metric makes it difficult to determine the underlying causes of observed effects. New computational techniques such as "classification images" (stimulus-based templates of the criteria observers employ while performing tasks) offer an opportunity to narrow this gap. Another series of experiments demonstrates that classification images can be adapted to accurately characterize VPL in detail. Observers were trained to detect oriented gratings, similar to classical VPL studies, or coherent motion stimuli, replicating the previous experiments. Images computed from oriented gratings parallel the psychophysical data and present a more complete view of stimulus sensitivity. Images computed from coherent motion stimuli show clear beneficiary effects of feedback that are strikingly consistent with the aforementioned results. Furthermore, the images reveal a temporal"blink" effect, suggesting that observers preferentially process later frames of the stimuli, as well as a spatial bias indicating that observer focus shifts to spatial locations congruent with direction of motion. These effects would have remained hidden without the sensitivity provided by classification images. The results of these experiments show that feedback exerts powerful effects on the stabilization of VPL, and that classification images can reveal such perceptual dynamics in great detail

An Evaluation of the Visual Demands of Portable Telematics Technologies among Young Adult Drivers

Proposed visual-manual distraction guidelines for in-vehicle electronic devices (NHTSA, 2012) specify 3 criteria by which unacceptable levels of visual distraction are to be quantified using driving simulation testing. This paper reports on data obtained on a sample of 24 younger adults (20-29 years) dialing a flip-style phone with tactile buttons and a smart phone with a touch screen, entering a destination address into a portable navigation device, and, for comparison purposes, manually interacting with the vehicle radio at 3 distinct levels of complexity. It is our intent to limit this document to a presentation of the results and allow readers to consider the data in relation to the proposed distraction guidelines for in-vehicle devices and possible implications for the eventual development of guidelines for nomadic devices. No overt support or critique of the guidelines is offered by the authors in this context. It is our expectation that making these data available may be a useful contribution to the overall discussion of the proposed and future guidelines

The effects of Chinese typeface design, stroke weight, and contrast polarity on glance based legibility

Modern interfaces increasingly rely on screens filled with digital text to display information to users. Previous research has shown that even relatively subtle differences in the design of the on-screen typeface can influence to-device glance time in a measurable and meaningful way (Reimer et al., 2014). Here we outline a methodology for rapidly and flexibly investigating the legibility of typefaces on digital screens in glance-like contexts, and apply this method to a comparison of 5 Simplified Chinese typefaces. We find that the legibility of the typefaces, measured as the minimum presentation time needed to read character strings accurately and respond to a yes/no lexical decision task, is sensitive to differences in the typeface's design characteristics. The most legible typeface under study ("MT YingHei") could be read 33.1% faster than the least legible typeface in this glance-induced context. A second study examined two different weights of the MT YingHei type family (medium and bold), as well as two contrast polarity (color) conditions to investigate how these variations impact legibility thresholds. Results indicate that bold weight text is easier to read in this enforced glance-like context, and that positive polarity text (black on white) is easier to read compared to white on black text under the lighting conditions considered. These results are discussed in terms of contextual factors that may mediate glance-reading behavior, as well as how type design interacts with the practical limitations of a moderate density pixel grid. (C) 2015 Elsevier B.V. All rights reserved

A Secondary Assessment of the Impact of Voice Interface Turn Delays on Driver Attention and Arousal in Field Conditions

Voice interface use has become increasingly popular in vehicles. It is important that these systems divert drivers’ attention from the primary driving task as little as possible, and numerous efforts have been devoted to categorizing demands associated with these systems. Nonetheless, there is still much to be learned about how various implementation characteristics impact attention. This study presents a secondary analysis of the delay time between when users finish giving commands and when the system responds. It considers data collected on 4 different production vehicle voice interfaces and a mounted smartphone in field driving. Collapsing across systems, drivers showed an initial increase in heart rate, skin conductance level, and off-road glance time while waiting for a system to respond; a gradual decrease followed as delays continued. The observed attentional and arousal changes are likely due to an increase in anticipation following a speech command, followed by a general disengagement from the interface as delay times increase. Safety concerns associated with extended delay times and suggestion of an optimal range for system response times are highlighted