Jeff K. Caird

A meta-analysis of the effects of cell phones on driver performance.

The empirical basis for legislation to limit cell phones while driving is addressed. A comprehensive meta-analysis of the effects of cell phones on driving performance was performed. A total of 33 studies collected through 2007 that met inclusion criteria yielded 94 effect size estimates, with a total sample size of approximately 2000 participants. The dependent variables of reaction time, lateral vehicle control, headway and speed and the moderating variables of research setting (i.e., laboratory, simulator, on-road), conversation target (passenger, cell phone) and conversation type (cognitive task, naturalistic) were coded. Reaction time (RT) to events and stimuli while talking produced the largest performance decrements. Handheld and hands-free phones produced similar RT decrements. Overall, a mean increase in RT of .25s was found to all types of phone-related tasks. Observed performance decrements probably underestimate the true behavior of drivers with mobile phones in their own vehicles. In addition, drivers using either phone type do not appreciably compensate by giving greater headway or reducing speed. Tests for moderator effects on RT and speed found no statistically significant effect size differences across laboratory, driving simulation and on-road research settings. The implications of the results for legislation and future research are considered.

Visual search for traffic signs: the effects of clutter, luminance, and aging.

Latency and eye movement measures were used to examine the effects of aging, clutter, and luminance on visual search for traffic signs embedded in digitized images of driving scenes. Initially 14 older and 14 younger observers classified daytime and nighttime traffic scenes as containing low or high amounts of clutter. Next, an independent sample of 14 younger and 14 older participants searched for traffic signs contained within these scenes. Errors were more common among the elderly. Search efficiency declined with increased clutter and with aging. However, relative to the young, older adults did not suffer disproportionately as a result of increased clutter. The methods developed might be profitably employed to assess sign conspicuity and sign acquisition during driving.

Local applications of the ecological approach to human-machine systems

Contents: Preface. W. Schiff, W. Arnone, Perceiving and Driving: Where Parallel Roads Meet. S.B. Flynn, T.A. Stoffregen, Perceiving and Avoiding Rollover in Agricultural Tractors. J.M. Flach, R. Warren, Low-Altitude Flight. J. Grosz, R.T. Rysdyk, R.J. Bootsma, J.A. Mulder, J.C. van der Vaart, P.C.W. van Wieringen, Perceptual Support for Timing of the Flare in the Landing of an Aircraft. G.E. Riccio, Coordination of Postural Control and Vehicular Control: Implications for Multimodal Perception and Simulation of Self-Motion. G.J.F. Smets, Designing for Telepresence: The Delft Virtual Window System. J.P. Hansen, Representation of System Invariants by Optical Invariants in Configural Displays for Process Control. L.A. Whitaker, V.G. CuQlock-Knopp, Human Exploration and Perception in Off-Road Navigation. H.L. Pick, M.R. Heinrichs, D.R. Montello, K. Smith, C.N. Sullivan, W.B. Thompson, Topographic Map Reading. R.R. Hoffman, R.J. Pike, On the Specification of the Information Available for the Perception and Description of the Natural Terrain. G. Klein, B.W. Crandal, The Role of Mental Simulation in Problem Solving and Decision Making. M.F. Young, M.D. McNeese, A Situated Cognition Approach to Problem Solving. L.D. Segal, Designing Team Workstations: The Choregraphy of Teamwork. P.N. Kugler, G. Lintern, Risk Management and the Evolution of Instability in Large-Scale, Industrial Systems.

Older Driver Failures of Attention at Intersections: Using Change Blindness Methods to Assess Turn Decision Accuracy:

A modified version of the flicker technique to induce change blindness was used to examine the effects of time constraints on decision-making accuracy at intersections on a total of 62 young (18-25 years), middle-aged (26-64 years), young-old (65-73 years), and old-old (74 + years) drivers. Thirty-six intersection photographs were manipulated so that one object (i.e., pedestrian, vehicle, sign, or traffic control device) in the scene would change when the images were alternated for either 5 or 8 s using the modified flicker method. Young and middle-aged drivers made significantly more correct decisions than did young-old and old-old drivers. Logistic regression analysis of the data indicated that age and/or time were significant predictors of decision performance in 14 of the 36 intersections. Actual or potential applications of this research include driving assessment and crash investigation.

The effects of practice with MP3 players on driving performance

This study examined the effects of repeated iPod interactions on driver performance to determine if performance decrements decreased with practice. Nineteen younger drivers (mean age=19.4, range 18-22) participated in a seven session study in the University of Calgary Driving Simulator (UCDS). Drivers encountered a number of critical events on the roadways while interacting with an iPod including a pedestrian entering the roadway, a vehicle pullout, and a lead vehicle braking. Measures of hazard response, vehicle control, eye movements, and secondary task performance were analyzed. Increases in perception response time (PRT) and collisions were found while drivers were performing the difficult iPod tasks, which involved finding a specific song within the song titles menu. Over the course of the six experimental sessions, driving performance improved in all conditions. Difficult iPod interactions significantly increased the amount of visual attention directed into the vehicle above that of the baseline condition. With practice, slowed responses to driving hazards while interacting with the iPod declined somewhat, but a decrement still remained relative to the baseline condition. The multivariate results suggest that access to difficult iPod tasks while vehicles are in motion should be curtailed.

Age differences in visual search for traffic signs during a simulated conversation.

The effects of divided attention were examined in younger adults (M = 23 years) and older adults (M = 64 years) who searched for traffic signs in digitized images of traffic scenes. Sign search was executed under single-task and dual-task conditions in scenes containing either small or large amounts of visual clutter. For both age groups, clutter and the secondary task had additive effects on search accuracy, speed, and oculomotor involvement. Compared with the younger adults, older adults were less accurate, especially with high-clutter scenes, were slower to decide that a target sign was not present, and exhibited a marginally greater divided-attention effect on reaction times. They exhibited longer fixations in the divided-attention condition, in which they also showed a disproportionate reduction in recognition memory for the content of the secondary task. Actual or potential applications of this research include methods for evaluating the distraction of conversations and safety implications of conversation on visual search behavior.

Experimental Evaluation of a Model of Mental Workload

This study was designed to test predictions from a model of mental workload. The model predicts that mental workload grows as perceived distance from a task goal increases and the effective time for action decreases. Decreases in workload can be achieved by actions that bring the task goal into the region of acceptable time/distance constraints for successful resolution. We reported an experiment that tested these assertions using the Timepools performance task. Timepools generates a spatial representation of a shrinking temporal target to assess the effects of path length (i.e., the number of sequential targets to be acquired) and shrink rate (i.e., elapsed time during which the circle is halved in area) on reaction time (RT), movement time (MT), error rate, and the subjective perception of workload. Data from the experiment indicated systematic effects for task-related factors across performance and workload measures. Path length and shrink rate had differential effects on both RT and MT, which were also reflected in the components of the individual workload scales. The results support a general form of the workload model which may help researchers and practitioners in the difficult task of work load prediction

The blind date: The effects of change blindness, passenger conversation and gender on looked-but-failed-to-see (LBFTS) errors

This study examined situations where drivers looked-but-failed-to-see (LBFTS) hazards, and whether passenger conversation and gender affected hazard detection rates. To reliably produce LBFTS errors, 40 young drivers (M=20.3) encountered motorcycles and pedestrians while making left turns in the University of Calgary Driving Simulator (UCDS). Prior to turn initiation the UCDS screens flickered using an extension of change blindness methods. In addition, drivers either drove alone or conversed with an attractive confederate passenger. Measures of LBFTS errors, hazard detection and social factors were analyzed. Higher rates of LBFTS errors and hazard detection occurred while conversing than while driving alone. A discriminant function analysis (DFA) using conversation and gender as predictors accurately classified LBFTS errors. Higher passenger attraction and higher extroversion were related to critical events being missed. The basis of LBFTS errors in divided and selective attention and classification implications are discussed.

Effects of passenger and cellular phone conversations on driver distraction

The distracting effects of a simulated conversation with passengers and those of a conversation over a hands-free cellular phone were compared. The conversation was also analyzed to determine if passengers modulated their conversations as driving demands changed. Eighty participants were randomly assigned to one of three conditions: driving alone, driving with a passenger, and driving with a cellular phone. Drivers drove through residential and urban traffic environments in a fixed-based driving simulator in which a variety of events occurred, such as pedestrian activity, oncoming vehicles, and intersections. The results indicated that lane and speed maintenance were influenced by increased driving demands. Response times to a pedestrian incursion increased when the driver was driving and talking compared with those detected when the driver was not talking at all. Contrary to what some researchers have assumed, there was little practical evidence that passengers adjusted their conversations to changes in the traffic environment. The workload was rated higher when the driver was driving and talking and was also rated higher by drivers than by nondrivers. The discussion focuses on future research and implications for driver safety and training.

Effects of Conformal and Nonconformal Vision Enhancement Systems on Older-Driver Performance

The effects of two types of vision enhancement system (VES) displays on younger- and older-driver performance were systematically examined in various contexts. Younger and older drivers used either a conformal or a nonconformal VES display while driving in a fixed-base driving simulator. Within each block of trials, traffic scenarios were used to test driver performance: everyday driving, intersection approaches, emergency events, and VES failure. Conformal imagery directly highlighted aspects of the traffic environment, whereas nonconformal displays were coupled to environmental events but not superimposed on them. In all driving scenarios, conformal displays had a performance advantage over nonconformal displays. These advantages, however, depended on what was highlighted and whether a highlight covered or obscured important information about the environment. The perceived benefits of VESs are in situations where visibility is limited by weather (e.g., fog, snow, or rain), time of day (e.g., night or dusk), or roadway geometry (e.g., curves or railway crossings). Implications of the results for the design of conformal and nonconformal VESs and for future research are discussed.