A Road-Crossing Guidance Smartphone Application Study Suggests Using Permissive Alerts to Help Older Adults Avoid Missed Opportunities for Crossing.

Researchers Assessed the Effectiveness of a Smartphone Application Virtually Tested Among Older Pedestrians to Assist in Street Crossing Decisions.

Date Posted

Determining the Effect of Smartphone Alerts and Warnings on Older-Adult Street-Crossing Behavior

Summary Information

Research has shown that older pedestrians have more difficulty making road-crossing decisions than younger adults, which presents an opportunity for vehicle-to-pedestrian (V2P) communication to assist older adults’ street-crossing decisions. This study developed an application (app) for smartphones generating visual, haptic, and auditory  permissive alerts (safe to cross) and prohibitive warnings (not safe to cross) in a virtual street-crossing environment. A between-subjects study (i.e., different people test each condition) was completed with 66 participants ages 65-84 to understand the effects of these alerts and warnings. Each user’s brisk walking speed was considered to determine whether it was safe to cross the street in a stream of traffic. Participants’ behavior under three different conditions were studied: i) permissive where the participants held a mobile phone and received alerts telling them when it was safe to cross, ii) prohibitive where the participants held a mobile phone and received warnings telling them that it was not safe to cross, iii) control where the participants held a mobile phone throughout the road-crossing session but did not receive any alerts.

Lessons Learned

  • Use permissive alerts to help older adults avoid missed opportunities for crossing. This study found that participants in the control condition were conservative overall, letting gaps go that were crossable given their walking speed. Participants complied with the permissive alerts (safe to cross) but often did not comply with the prohibitive warnings (not safe to cross) and nearly half of participants who received the prohibitive warnings stated that the app was annoying. Participants who received permissive alerts also took smaller gaps than participants who received prohibitive warnings or those in the control condition.
  • Consider different settings (e.g., urban, rural) when conducting research related to older adults. In this study, participants found utility in the alerts, including making road crossing easier, but realized that they may not need them immediately in real life. However, the participants saw the potential of the alert to help in riskier settings, including when they get older or are in riskier contexts (e.g., high traffic, reduced vision).
  • Develop apps for older pedestrians that are ability-based. In this study, it was confirmed that age (in years) was a significant predictor of all movement timing measures; as age increased, participants initiated their movement less quickly and crossed the road more slowly. These age-related declines in time to spare when exiting the roadway demands ability-based alerts and warnings.
  • Determine the proper timing when sending an alert. On the one hand, alerts can be ineffective when sent very close in time to when participants had initiated a crossing movement. On the other hand, the study results show that alerts can also be confusing if they are sent too early and it may be difficult for the pedestrians to cognitively link the auditory warning to the visually perceived gap.
  • Consider ways to implement Augmented Reality (AR) to visually highlight gaps. Permissive alerts were timed such that the verbal indication of “Safe to Cross” was complete before the gap appeared and when there was still a car in front of the person, which can sometimes cause confusion. Highlighting the approaching gap in an AR display may help improve both alerts and warnings.

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