Keying While Listening: The Effect of Input Grouping

A study was conducted to explore the effect that the temporal grouping of spoken digits has on keyboard entry. Each subject had to key a series of 12-digit messages in an overlapping manner, i.e., he began keying early in the digit sequence and continued to key previously spoken digits while listening to incoming digits. The digits in a message were either spoken with even spacing or they were grouped into three series of four digits each, with pauses between groups. Total message time was equated for grouped and ungrouped messages. Performance was superior for grouped messages. Memory load, defined as the number of digits received in memory but not yet keyed, was higher for grouped messages. The results are discussed in terms of the division and switching of attention between input and output processes.