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**Subjects** We will run 30 participants recruited from the University of Illinois at Urbana-Champaign course credit subject pool. **Apparatus** View distance: 57 cm, with subjects stabilized on a chinrest Monitor: BenQ XL2420TX (1920 x 1080, max refresh rate of 100 Hz running at 60 Hz) **Stimuli** The experiment was programmed using the Psychopy library for Python. Positions are given in degrees visual angle and are relative to the center of the screen; (0, 0) is in the center, negative values are down and left, and positive values are up and right. After an instruction screen, subjects are presented with the trial stimuli. The play area is a 15.53 by 15.53 degree square on a white background. On the left and right edges of the play area are light gray (211, 211, 211) "sidewalks," each subtending 2.66 by 15.53 degrees visual angle, while a dark gray "road" (128, 128, 128) subtending 10.21 by 15.53 degrees visual angle lies between the sidewalks. The avatar under the control of the subject is a .82 by .82 degree purple (128, 0, 128) pentagon. The pentagon is irregular, shaped like a square except that either the left or right edge is instead two edges that form a point. The avatar points in the direction the player can move; it is on the left side and points left when players start a crossing from the right side, and is on the right side and points right when they cross from the left. It switches direction when players complete a crossing. It sits at a fixed vertical position of -1.94 degrees, but moves left or right at a rate of 3.7 degrees per second when the left or right arrow keys are pressed. At the beginning of each block, its position is in the middle of the left sidewalk (-6.43, -1.94) pointing left, so that it must move towards the seed basket before it re-orients and allows left-to-right movement. On the left side of the screen (8.34, -1.94) is the "seed basket," a 1.4 by 1.4 degree picture of a brown basket filled with multicolored seeds. On the right side of the screen (9.0, -.78) is the "barn," a 2.8 by 2.8 image of a pale green cartoon barn. If the player comes into contact with the basket, they will "pick up a seed," and a small circle (.2 degrees radius) randomly chosen to be one of 5 colors ("gold", (255,215,0); "light coral," (240,128,128); "light salmon," (255,160,122); "light sea green," (32,178,170); and "light sky blue," (135,206,250)) appears on the player's avatar. The seed remains with the player until they touch the barn, at which point a flower (2 x 2 degrees) the same color as the seed "blooms" beneath the barn and remains onscreen for 4.2 seconds before disappearing. During the trial, two sets of objects stream continuously through the display. One set, "pedestrians," consists of blue (0, 0, 255) equilateral triangles (base of .82 degrees) that move at a rate of 1.23 degrees per second, either from the bottom of the display to the top, or from the top to the bottom, chosen randomly at each spawn. They are confined to the sidewalks on either side, spawning at a fixed vertical distance that hides them outside the play area (y = -8.59 for upward-moving pedestrians and y = 8.59 for downward-moving pedestrians) and at a random X position in the range of the left sidewalk (between -5.1 and -7.77) or the right sidewalk (between 5.1 and 7.77). A pedestrian spawns every 900 ms, and there can be up to 10 onscreen at one time. They do not interact with the player avatar in any way, but will occlude the player if the avatar crosses their path. The other set of objects is the "cars." Cars are red (255, 0, 0) circles (.51 degree radius) that always move top to bottom in the display at a randomly chosen rate of 2.47, 3.70, 4.93, 6.16, 7.40, 8.63, or 9.86 degrees per second. Cars spawn randomly on the road (y = -8.28, x = between -7.77 and 7.77) every 400 ms. There can be up to 15 cars onscreen at once. Cars have a circular hitbox that has a radius 85% the size of their total radius (.44 degrees); if the edges of the player's avatar overlap with this hitbox, it is registered as a "collision" and on the next refresh the player is returned to the middle of whichever sidewalk they began crossing from ((-6.43, -1.94) if the crossing started on the left, (6.43, -1.94) if it started on the right). Probes also appear periodically throughout the trial. These are green (0, 128, 0) diamonds (1.03 degree width, 1.03 degree height).16 probes are randomly distributed across the 40 crossings players must complete. 8 probes appear behind the player (that is, on the side of the screen they are traveling away from) and half appear in front of the player (on the side of the screen they are traveling to). Of these, half appear "near" the player (2.66 degrees away on the x axis) or "far" from the player (6.20 degrees away on the x axis). One probe in each near/far x in front/behind condition appears in each of four quandrants in the y axis. The probe can appear anywhere in a 3.88 by 3.88 degree cell, centered at -5.82, -1.94, 1.94, and 5.82 degrees on the y-axis. Probes are triggered when the player crosses an invisible "trigger line," which can be anywhere between -1.33 and 1.33 degrees horizontally. Probes appear onscreen for 4.2 seconds. On top of the play area is a score counter that updates each time the player plants a flower; the player gets more points the faster they plant the flower after picking up the seed, calculated as max(1, 50/time to cross in seconds). There is also a "Flowers left to plant" indicator that starts at 20 and counts down each time the player plants a flower. **Procedure** On the initial block of the experiment, subjects are presented with instruction screens explaining the game they will be playing and featuring small, looping video clips demonstrating different aspects of play. They are informed that they must plant 20 flowers total, and that they get more points the faster they can plant the seed after picking it up. They are also told that the objects in the road will send them back to the sidewalk, forcing them to start over, but that the objects on the sidewalks won't affect them. They are further instructed that green probes will periodically appear, and that they are to press the space bar when they notice them. Once the subject presses a key, the block begins. Objects spawn and move continuously as the player moves back and forth. Each time the player plants a flower, they are awarded points relative to their crossing time and their "flowers left to plant" counter decreases by 1. There are 16 probes total. These appear at randomly designated crossings throughout the block, and the probe sequence is shuffled on each trial. Data is recorded on a probe-by-probe basis. For each probe, the following information is recorded: * whether the probe appeared in front of or behind the player * whether the probe appeared near or far away from the player * whether or not the probe was detected * the reaction time for response to the probe * the probe's x and y position * the player's x and y position at time of spawn * the Euclidean distance from the probe to the player at the time of spawn * the player's x and y position at time of detection or despawn (if the probe was not detected) * the Euclidean distance from the probe to the player at the time of detection or despawn (if the probe was not detected) * the x coordinates of the trigger line * the number of the crossing the probe spawned on * the block number When the block ends, subjects are shown a screen displaying their final score and the number of times they crossed. Subjects complete 3 blocks total.
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