2013 Conference Proceedings - University of Nevada, Las Vegas

Figure 5: Average hand trajectories during the numerical parity task,separated as a function of spatial compatibility.Results and DiscussionAll hand trajectories were rescaled into a standard coordinate space, [-1,1] x [0,1.5]. Toanalyze movements independent of reaction times, I used linear interpolation to normalize alltrajectories to consist of 101 times steps. This is important so that trajectories of differing timescales can be averaged over multiple trials. In addition, for ease of visualization, all trajectoriesfor responses on the right-hand side of the screen were reflected to the left side of the screen.The first analysis is with respect to the hand trajectories in each of two spatial compatibilityconditions. On consistent trials, participants responded to small numbers (1,2,3,4) on the leftside of the screen and large numbers (5,6,7,8) on the right side of the screen. On inconsistenttrials, these were reversed. These conditions are motivated by the robust finding that mostEnglish-speaking adults have an implicit left-right number orientation (Dehaene, Bossini, &Giroux, 1993).Proceedings of the 40 th Annual Meeting of the Research Council on Mathematics Learning 2013 208