Factors affecting numerical typing performance of young adults in a hear-and-type task

Abstract

Numerical hear-and-type tasks, i.e. making immediate keypresses according to verbally presented numbers, possess both practical and theoretical importance but received relatively little attention. Effects of speech rates (500-ms vs. 1000-ms interval), urgency (urgent condition: performance-based monetary incentive plus time limit vs. non-urgent condition: flat-rate compensation) and finger strategies (single vs. multi-finger typing) on typing speed and accuracy were investigated. Fast speech rate and multi-finger typing produced more errors and slower typing speed. Urgency improved typing speed but decreased accuracy. Errors were almost doubled under urgent condition, while urgency effect on speed was similar to that of speech rate. Examination of error patterns did not fully support Salthouse's (1986) speculations about error-making mechanisms. The results implied that urgency could play a more important role in error-making than task demands. Numerical keyboard design and error detection could benefit from spatial incidence of errors found in this study.

Statement of Relevance: This study revealed that classic speculations about error-making mechanisms in alphabetical typing do not necessarily translate to numerical typing. Factors other than external task demands such as urgency can affect typing performance to a similar or greater extent. Investigations of intrinsic error-making factors in non-traditional typing tasks are encouraged.

Keywords:

• numerical typing
• errors
• multi-tasking
• serial reaction time
• speed–accuracy trade-off

Notes

1. One may argue that the delay could have been generated from no concurrent manual tasks; that is, the subsequent manual movement has to wait until the completion of the current movement, and, therefore, the delay of consecutive tasks was caused by intra-modality interference rather than inter-modality. However, if the delay had happened at motor response stage, the duration of the movement would have been unreasonably long. See Appendix 2 for details.

2. Since there was no interaction between factors, it would be reasonable to stratify the errors by factorial pairs, i.e. single vs. multi-finger, fast vs. slow speech rate and urgent vs. non-urgent instead of comparing between eight factorial combinations to assure enough sample size (>30).