Participants
64 participants were recruited, 31 older adults aged between 60 and 83 years old (y/o, mean=69.03, SE=1.38), and 33 younger adults aged between 18 and 35 y/o (mean=22.37, SE=0.91). All younger adults were recruited at Bournemouth University, UK. All participants had normal or corrected to normal vision. Participants were screened for mild cognitive impairment using the MoCA (Nasreddine et al., 2005). One older adult was excluded based on a cut-off score of 23 (Luis, Keegan, & Mullan, 2009). Therefore 30 older adults and 33 younger adults were included in the final analyses. The study was approved by Bournemouth University’s ethics committee. Informed consent was obtained from participants prior to taking part. Participants took part in exchange for course credits or monetary compensation for their time. This study was performed in accordance with all appropriate institutional and international guidelines and regulations, in line with the principles of the Helsinki Declaration.

 Apparatus
During the experiment participants’ eye movements were recorded at a sampling rate of 1000Hz with the SR-Research EyeLink 1000 (with a chin and forehead rest), which has an average gaze position error of about 0.25° and a spatial resolution of 0.01°. Only the dominant eye was tracked. Stimuli were presented on an HP monitor
with a screen resolution of 1920 by 1080 pixels, a width of 534mm and a height of 300mm, a horizontal viewing angle of 46.9° and a vertical viewing angle of 27.4° at a distance of 740mm. The experiment was coded in Matlab (MATLAB, 2016) using the Psychophysics toolbox, PTB-3 (Brainard, 1997) and EyeLink Toolbox extensions
(Cornelissen et al., 2002). Calibrations for eye fixations were conducted at the beginning of the experiment using a nine-point fixation procedure as implemented in the EyeLink API (see EyeLink Manual) and using Matlab software. Calibrations were then validated with EyeLink software and repeated until there was less than 1° of error for every calibration point.

Executive Function Tests
To assess the participants’ executive function abilities, participants completed the BADS zoo map test (B. A. Wilson et al., 1996), and the Rogers and Monsell attention shift paradigm (RMA; Rogers & Monsell, 1995). The BADS zoo map test assessed the participants’ spatial planning ability by assessing participants’ ability to plan a
route around a zoo. In the first trial participants were given a map of a zoo and instructed to plan a route around a zoo, starting at the entrance and finishing with a picnic. Along the route participants had to visit specified locations in any order while following set rules, such as only using specific paths twice and not visiting unspecified locations. Participants’ planning time and time to complete the task was recorded. In the second trial participants had to plan a route around the same zoo, following the same rules, and visiting the same locations but in a specified order. Again, the participants’ planning time and time to complete the task were recorded. Participants were scored based on visiting the correct locations and points were deducted when participants break the rules and exceed time limits for planning on the second trial. There was only one correct route in both trials, therefore, if participants did the task correctly their route for trial one would mostly match the route for trial two. The only exception being the order in which they went around a loop section of the map.

The RMA assessed participants’ attentional control by getting participants to switch between two similar tasks. Participants were presented with number letter pairs (e.g., 9E) and depending on the position of the stimulus on the screen they either had to identify whether the number was odd or even or whether the letter
was a vowel or consonant. For the RMA task I extracted the global and local switch costs as done by Rogers and Monsell (1995). The global switch costs refer to the difference in performance between a block where participants perform the same task and a block where participants are switching between tasks. Local switch costs refer to the differences in performance between switch and non-switch trials. These tests have previously been linked to road crossing ability (Dommes et al., 2013; Geraghty et al., 2016) and were designed to assess participants’ spatial planning and attention shifting abilities.

 Experimental Procedure 
I used the same video stimulus and design as in Nicholls et al. (2019). At the beginning of the experiment participants were informed that they would be presented with a series of videos of road crossing situations on screen and that they would have to indicate by pressing the spacebar on a keyboard when they could cross the road and hold the button pressed for as long as they thought it was safe to cross. Participants were instructed to focus on approaching vehicles on the side of the road closest to them but vehicles did travel on both sides of the road (see Figure 3.1A for a capture of the scene). Vehicles travelled at an average velocity of 50 km/h. Each
trial started with the presentation of a central fixation cross. Once the participants had fixated on the cross a blank screen was presented for 500 ms and then the video clip for the trial was presented (see Figure 3.1A). Each trial was followed by another blank screen for 500 ms and the next trial started with the central cross. One hundred trials were presented to the participants each with a different video clip, each lasting 10 seconds. All video clips were filmed at a real road crossing in Fribourg with a variety of traffic densities, with or without pedestrians and cyclists (distractors). The videos were completely natural, and no aspects of the videos
were staged and they were not edited to control when the cars emerged. Thirty-five of the videos contained pedestrians. The camera was always fixed in the same location, at a height in between the average adult and the average child’s height. All video clips were mirrored so as to simulate a road crossing in the UK. Critically, registration numbers were not identifiable and the visual scenes did not include any information allowing participants to identify where they were filmed. Prior to the experiment, 10 British drivers were asked where the video clips were located, all of whom responded with a location in the UK. Number of presses for each trial were
collected and analysed for the purpose of the present experiment.