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Experiment Author Cooper, A.N., & Shepard, R.N. Adapted from STEP and used with permission of Brian MacWhinney
Participants are shown a letter, then a direction of orientation that it will appear in when it is presented as a target. They are given time to produce somehow a stimulus that they then compare to the target, rotated letter to see whether it is canonical or reflected.
There will be four blocks of 18 trials each. Each trial will present a letter or number that is rotated and sometimes mirrored. On some blocks, participants are given information about the upcoming trials, such as which character will appear or what orientation it will have. Within each block, you will always be given the same type of advance information. Participants are to determine if the rotated character is mirrored or not.
Cooper, A.N., & Shepard, R.N. (1973). The time required to prepare for a rotated stimulus. Memory & Cognition, 1, 246-250.
Experiment Abstract or Original Experiment Abstract
Average time required to determine whether an alphanumeric character was presented in its normal version or as its mirror image increased from 500 msec to 1,000 msec as its angular departure from upright increased from 0 to 180 deg. However, when Ss already knew the identity of the upcoming character and when advance information as to its orientation was available for 1,000 msec, this reaction time was reduced to about 400 msec regardless of the orientation of the test stimulus. In this case, Ss claimed that they could prepare for the rotated stimulus by imagining the normal version of the designated character rotated into the indicated orientation and that they could then rapidly test for a match against the ensuing stimulus.
Works Cited by the Experiment
Cooper, L.A., & Shepard, R.N. Chronometric studies of the rotation of mental images. In W.G. Chase (Ed.), Virtual information processing. New York: Academic Press, in press.
Shepard, R.N. Studies of the form, formation, and transformation of internal representations. In Cogntive mechanisms. Washington, D.C. Winston & Sons, in press.
Shepard, R.N., & Metzler, J. Mental rotation of three-dimensional objects. Science, 1971, 171, 701-703.