| In this experiment the estimation ability of college undergraduates was examined using a number line task, with lines numbered 0-to-100, 0-to1,000 and 0-to-723 presented on a computer monitor. Previous research on kindergarteners' through 6th graders' ability to estimate showed a progression from a logarithmic mental representation of numbers to a linear mental number line. Children's ability to estimate was found to correlate strongly with math achievement. We used this task to examine the hypothesis that remnants of the underlying logarithmic number line representation persist into adulthood despite formal educational experience with the number system (e.g. Dehaene, 1997). 0 to 723 number lines were presented to add novel mid- and end-points, due to previous research showing that the mid-points of 0 to 100 and 0 to 1,000 lines were used as reference points. Accuracy of estimates and reaction times were analyzed for each subject along with eye-movements in order to help define strategy use in performing the task. In particular, we captured participants' eye fixations within several defined regions of interest along the number lines as a way of identifying their estimation strategies. We presented overlays of fixations and saccades to show exemplars of the several strategies we have observed. Statistical analysis of these strategies was discussed and a comparison of strategy use with estimation accuracy was examined. |
