Operator error performance and keyboard evaluation in Palantype machine shorthand

The output of a Palantype shorthand machine can be processed and displayed electronically to provide a simultaneous transcript of speech for the deaf. Operator errors have been identified as the most important factor limiting the legibility of the output text. Tests performed on Palantype machines have shown that large variations in error performance can result from mechanical differences between machines and from maladjustment of the switches fitted to them. Keyboards using commercially available keyswitches have therefore been designed to replace the Palantype machine itself as an input device for this application and hence to minimize operator errors. This paper discusses the design features of a replacement keyboard and presents the results of a series of experiments to compare the performance of three possible keyboards with both 'good' and 'poor' examples of conventional mechanical Palantype machines with electrical switches fitted.