“…It is well established that some stimulus-response mapping arrangements are more natural or compatible than others (Fitts & Deininger, 1954;Fitts & Seeger, 1953). A large number of experiments using the additive factors method (Sternberg, 1969) support the commonsense view that stimulus-response (S-R) compatibility effects are confined to the response selection stage (e.g., Alluisi, Strain, & Thurmond, 1964;Frowein & Sanders, 1978;Hasbroucq, Guiard, & Kornblum, 1989;Inhoff, Rosenbaum, Gordon, & Campbell, 1984;Schwartz, Pomerantz, & Egeth, 1977;Shulman & McConkie, 1973;Spijkers & Walter, 1985;Whitaker, 1979). A manipulation of S-R compatibility in the locus-of-slack paradigm should distinguish central-bottleneck models from late-bottleneck models.…”