Solving the rod-and-frame test in a tachistoscopic presentation: effects of stimulus size and perceptual style.

This research was undertaken to demonstrate, with correlational evidence, that presenting the rod-and-fi’ame test (RFT) with either limited (tachistoscopic) or unlimited (Oltman’s, 1968, portable RFT) exposure time does not significantly affect the ranking of subjects. The underlying hypothesiis is that the intersubject variability of performance on the portable RFT is due essentially to differences in sensitivity to the optostatic vection that appears automatically and almost immediately. Results of the tachistoscopic test show that the effect of angular size of the stimulus is similar to that described in the literature for unlimited time situations, and that subjects’ ranking is very similar regardless of the exposure time (W = .80). However, although a difference is observed between the means of low and high achievers in beth types of RFT, intraindividual intertask homogeneity (correlation coefficient) is not verified in each of these subgroups. From these results, one can distinguish two processes in the RFT: the first, vections, has to do with the subject’s postural orientation and seems to play a great role in organizing interindividual differences. The second process, a more cognitive one, has a less striking effect and has to do with the selection of reference frames in perceptual organization.