Modeling Millisecond Time Interval Estimation in Space Fortress Game

Modeling Millisecond Time Interval Estimation in Space Fortress Game Jungaa Moon (jungaam@andrew.cmu.edu) John R. Anderson (ja+@cmu.edu) Department of Psychology, Carnegie Mellon University Pittsburgh, PA 15213 USA Abstract multitasking situations. As in the driving example, time estimation is often an implicit secondary task that one performs to coordinate primary tasks. In addition, people sometimes need to estimate multiple time intervals concurrently (e.g., cooking breakfast). It seems plausible that time estimation in those circumstances will exhibit properties not seen when it is performed as an isolated task in a static environment. We investigated this question in the Space Fortress task (Donchin, 1989), a video game that simulates real-time complex tasks performed in dynamic environments (e.g., piloting an aircraft). We investigated sources of the asymmetric bias found in estimation of a time interval (250-400 ms) embedded in the Space Fortress task (Donchin, 1989). Two hypotheses to explain this bias were tested in a behavioral experiment: 1) contamination from a different time interval representation, and 2) pressure to complete the task in time. Participants alternated between producing the target interval and producing either a shorter or a longer interval while the total time allowed for the task was manipulated. The results showed that the target interval estimate was significantly influenced by both manipulations. The effects were captured by incorporating the timing model of Taatgen and Van Rijn (2011) into the ACT-R model for Space Fortress (Bothell, 2010). Time estimation performed in a dynamic task requires understanding the influence of external temporal tasks as well as the procedural demands of performing multiple tasks under time pressure. Time Interval Estimation in Space Fortress Task The goal of the Space Fortress task (Figure 1) is to maximize the total scores by navigating a ship in a frictionless space, destroying a fortress multiple times and handling mines while protecting the ship from the fortress and mines. The participant navigates the ship by rotating left or right (A/D keys) or thrusting (W key) to make it fly within an area enclosed by two hexagons. A fortress stationed in the center rotates like a turret, tracking the ship’s trajectory and firing shells at it. The participant has to shoot the fortress with a missile (spacebar) at least ten times and then make a rapid double-shot to destroy it. Keywords: Time estimation; cognitive model; multitasking. Introduction Time interval estimation underlies various skills such as motor control (Ivry, Spencer, Zelaznik, & Diedrichsen, 2002), musical performance (Jones, 1990), and speech processing (Schirmer, 2004). Millisecond-to-second interval timing is critical in real-time dynamic tasks that require adaptive responses to the changing environment. For instance, when driving it is necessary to estimate how long one can attend to a navigator before switching back to attending to the road and driving control (Salvucci, Taatgen, & Kushleyeva, 2006). Time estimation can be studied under various paradigms (Zakay, 1990). Participants can be asked to retrospectively generate verbal estimation of an interval, to judge whether a presented interval is the same length as a target interval, or reproduce a target interval. Studies using the reproduction paradigm typically show response distributions that are 1) centered at the real-time criteria, 2) symmetrical, and 3) have a standard deviations that increase in proportion to the mean interval (e.g. Rakitin, Gibbon, Penney, Malapani, Hinton, & Meck, 1998). In most studies under those paradigms, time estimation is often an isolated task performed in a static environment. It is the primary task on which participants focus, even when a secondary task is given for various purposes (Fortin, Rousseau, Bourque, Kirouac, 1993; Rakitin, et al., 1998). However, one may wonder to what extent the time estimation performed in those paradigms reflects the time estimation that people usually perform in various Figure 1: Schematic representation of the Space Fortress task (left) and performance in the IFF tapping task (right). The mine task, which is the focus of the current study, consists of a series of activities in a specific order. At the beginning of the game, the participant is presented with a screen with three alphabetic letters (‘foe letters’) and asked to remember them. During the game, a mine appears at a random location on the screen 5 seconds after the destruction of the previous mine and starts pursuing the ship with the intent of crashing into the ship. When a mine appears, the participant has to check a letter that appears in