Transformation processes upon the visual code

Abstract

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 (RT) 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 code 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.

Mental rotation and orientation-dependence in shape recognition

“…Although there exists a small residual slope for these trials, this slope would translate to a hypothetical rate of rotation that is far faster than any previously found in studies that uncontroversially involve a rotation process (Shepard & Cooper, 1982). Shinar and Owen (1973), , and Simion et al (1982) obtained similar small orientation effects and ruled out mental rotation as a possible cause. These authors discuss several possible reasons why such slopes are not exactly zero.…”

“…Persistent small effects of orientation. A second problem for the rotation-for-handedness hypothesis is the repeated finding that orientation does have a significant effect on recognition time, albeit a small one Corballis & Nagourney, 1978;Simion et al, 1982). Corballis et al note that the rotation rate estimated from their data is far too fast to be caused by consistent use of Cooper and Shepard's mental rotation process; they suggest that it could be due to subjects' occasional use of mental rotation to double-check the results of an orientationinvariant recognition process, resulting in a small number of orientationsensitive data being averaged with a larger number of unvarying data.…”

“…In trials where the cue information was accurate, White found no effect of orientation on either category or identity judgments, either for standard or mirror-reversed characters, but did find a linear effect of orientation on handedness judgments. Simion, Bagnara, Roncato, and Umilta (1982) had subjects perform "same/different" judgments on simultaneously presented letters separated by varying amounts of rotation. In several of their experiments they found significant effects of orientation on reaction time, but the effect was too small to be attributed to mental rotation.…”

On the Legibility of Mirror-Reflected and Rotated Text

“…Further evidence that readers are not performing rotations of individual letters comes from the fact that when single letters embedded in words are mirror-reversed, reading time is longer than if the entire word is mirror-reversed [9,10,136,139]. Observers are in fact able to identify a rotated letter even before determining whether it is mirror-reflected or not, suggesting that they do not need to perform mental rotation for identification or naming of simple patterns [140][141][142][143][144][145] and even for novel letter-like shapes [66] (although they can mentally rotate the images if the task demands it [146]). Unlike for objects [147,148], identification time for letters does not depend on letter orientation.…”

“…For example, an inverted 'A' may provide a cue that the entire text is inverted. Reading of inverted, mirrored, or rotated text involves a detection or an alignment of an appropriate frame of reference [143,167,[175][176][177]. As a result, response time to individual letters at different orientations is predicted by the orientation of the previously seen letter [178].…”