Effects of Non-Verbal Communication Cues on Decisions and Confidence of Drivers at an Uncontrolled Intersection

Abstract

Summary: Drivers read other drivers' intentions using various non-verbal communication cues in situations where traffic regulations play only a limited role. Although such communication is important to reach safe joint actions with other driver(s), effects of communication have not been fully understood. The objective of this study was to understand effects of communication cues on driver's decisions and confidence. Straight-cross-path and left-turn scenarios around an uncontrolled intersection were studied in an interview-based experiment using 65 subjects. The subject's car approached the intersection while another car was approaching the same intersection and sent communication cues consisting of various combinations of vehicle behaviors (constant speed, speeding up, and slowing down) and hand gestures (meaning "Go ahead" and "Stop").Computer animations of the scenarios were presented to the subjects and terminated before the two cars reached the intersection. The subjects rated yielding frequency and confidence level for each cue combination in each scenario. The results showed that the vehicle behaviors and the hand gestures affected subjects' yielding frequencies and confidence levels. The cues also interacted with the priority rule in the left turn scenarios. The hand gestures were especially effective to consolidate subjects' decisions to yield or go with confidence when the priority rule was ineffective (i.e. in the straight-cross-path scenarios). The hand gestures were also effective to change the yielding frequencies to accept the cues conflicting with the effective priority rule (i.e. in the left-turn scenarios). Some requirements and recommendations for autonomous vehicle were discussed.

Interactions between cyclists and automated vehicles: Results of a photo experiment*

“…Sometimes, however, traffic rules are more ambiguous or the traffic situation is more demanding or complex, and informal right of way rules are applied. Road users might then communicate nonverbally to clarify their intentions and ensure a smooth interaction (Schramm, Rakotonirainy & Haworth, 2008;Kitazaki & Myrhe, 2015). Nonverbal communication includes signalling devices such as blinkers and brake lights, the vehicle's position and speed, and behaviour of the road user such as eye contact, nodding, and hand gestures (Kitazaki & Myrhe, 2015;Walker, 2005;Malmsten Lundgren et al, 2017).…”

“…Road users might then communicate nonverbally to clarify their intentions and ensure a smooth interaction (Schramm, Rakotonirainy & Haworth, 2008;Kitazaki & Myrhe, 2015). Nonverbal communication includes signalling devices such as blinkers and brake lights, the vehicle's position and speed, and behaviour of the road user such as eye contact, nodding, and hand gestures (Kitazaki & Myrhe, 2015;Walker, 2005;Malmsten Lundgren et al, 2017). Eye contact, nodding and hand signals are specifically relevant in driver-cyclist interactions because they well predict attention for and awareness of each other (Rakonitorainy, Feller & Haworth, 2008;Sucha, 2014).…”

Interaction between pedestrians and automated vehicles: A Wizard of Oz experiment

“…More specifically, pedestrians predict the behavior of vehicles (Level 3) based on their perception of vehicle and road features (Level 1) and their comprehension of the situation (Level 2). Vehicle features may include speed and distance (Brewer, Fitzpatrick, Turner, Whitacre, & Lord, 2005;Kadali & Vedagiri, 2013;Yannis, Papadimitriou, & Theofilatos, 2013) as well as cues provided by the driver inside the vehicle, such as eye contact and gestures (Habibovic, Andersson, Nilsson, Malmsten Lundgren, & Nilsson, 2016;Keferböck & Riener, 2015;Kitazaki & Myhre, 2015). Situation awareness, crossing decisions, and crossing behaviors of pedestrians are also influenced by environmental and individual factors (see the top of Fig.…”

“…Model of situation awareness in dynamic decision making, describing the interaction between a pedestrian and an AV (adapted from Endsley, 1995). not always possible, because the driver of the AV may be performing a non-driving task and therefore is not paying attention to the road (Kitazaki & Myhre, 2015;Rothenbücher et al, 2016). This means that pedestrians may be unable to differentiate between a distracted driver in a traditional vehicle and an AV driver performing a non-driving task, such as reading a newspaper.…”

“…The authors observed that simple indications (e.g., green pedestrian, green text ''walk", red text ''don't walk") were most indicative of whether it is safe or not to walk, while certain concepts (e.g., arrows, circles, etc) were more ambiguous. Based on an interview study, Kitazaki and Myhre (2015), provided a list of eight tentative recommendations for communication between pedestrians and AVs. For example, they recommended that autonomous vehicles should identify themselves on the body of the vehicle so that others can form an understanding and trust in AVs.…”