The roles of stimulus and response set size in the identification and categorisation of unidimensional stimuli

Dual mapping theories (e.g., Atkinson, Bower, & Crothers, 1965; Lacouture & Marley, 1991, 1995) propose that psychophysical judgment involves two comp onent processes: stimulus representation and response selection. This empir ical and theoretical paper studies the relative contributions of these two component processes in determining performance in the identification and ca tegorisation of unidimensional stimuli. We extend Lacouture and Marley's (1 995) mapping model of absolute identification to categorisation, and demons trate that the extension predicts that the number of response categories ha s a much larger effect than the number of stimuli in determining Various as pects of the relevant data, including the so-called bow effect. This predic tion is supported by the results of three experiments in which the number o f stimuli and/or the number of response categories was manipulated.