Perception & Psychophysics

, Volume 31, Issue 1, pp 13-25

First online:

Transformation processes upon the visual code

  • Francesca SimionAffiliated withInstitute of Developmental Psychology, University of Padua
  • , Sebastiano BagnaraAffiliated withInstitute of Psychology, National Research Council
  • , Sergio RoncatoAffiliated withInstitute of Psychology, University of Padua
  • , Carlo UmiltaAffiliated withInstitute of Human Physiology, University of Parma


Seven experiments investigated whether orientation-dependent latency functions for the visual code resemble those observed in studies of mental rotations of visual images. The subjects were required to perform “same-different” classifications of two simultaneously presented letters. The dependent variables considered were reaction time IRT and accuracy. Experiments 1, 2, 4, 5, and 6 showed that subjects could correctly classify two different letters on the basis of the visual code without preceding transformations. Experiments 1, 2, and 7 showed orientationdependent effects for “same“ responses. It appeared, however, that orientation functions for the visual cede were clearly different from those previously observed for visual images. In addition, the findings of Experiments 4, 5, and 6 indicated that a frame that jointly rotated with the disoriented letters could eliminate the orientation-dependent effects for “same” responses. Experiment 7 showed that the results of Experiments 4, 5, and 6 must be attributed to the structural characteristics of the frame and not to a directional cue. The results of Experiment 3 seemed to demonstrate that transformations did not occur when the subjects used the phonetic code to classify the letters. Overall, the results of the seven experiments were considered to provide a demonstration of the importance of the distinction between the operations on visual images and those on the visual code.