Sentence:  This resulted in four equal groups: fast <WSD>typers</WSD> in the speed payoff condition (IKIs of 184, 184, 198, 264, 286, and 309 msec), slow <WSD>typers</WSD> in the speed payoff condition (IKIs of 317, 382, 384, 394, 394, and 470 msec), fast <WSD>typers</WSD> in the accuracy payoff condition (IKIs of 211, 224, 226, 255, 259, and 276 msec), and slow <WSD>typers</WSD> in the accuracy payoff condition (IKIs of 290, 388, 403, 405, 443, and 451 msec). 
Meaning of the word marked with <WSD> tags:  Someone who (types); a typist.