“…1969·70. Psychon. Sci., 1971, VoL 22 (6) transformation (Posner & Rossman, 1965;Adams, Thorsheim, & McIntyre, 1969), perceptual-motor performance (Crowder, 1968), choice reaction (Pylyshyn, 1965), and verbal manl pulations (Kothurkar, 1968). Posner & Rossman (1965) and Crowder (1967aCrowder ( , b, 1968 underscore the need to place control upon such crucial variables as the nature of both the learned material and task activity, as well as prior experience with the interpolated activity.…”