Figural after-effects and apparent size

Sutherland (1954) obtained results which suggest that when the retinal size of test and inspection figures is equal, the direction of the FAE may be determined by the relative apparent sizes of the two figures. Other investigators have reproduced this result when exactly the same conditions were used: when the conditions were changed the result was not obtained. In the present paper these results are discussed and an attempt is made to determine why the effect is not obtained with small variations in the experimental conditions. It is further shown that some FAE phenomena cannot be explained by the two main existing theories; these phenomena could be explained if some analysis of the stimulus is being performed before the stage of the nervous system at which the process underlying FAEs occurs. Some recent physiological evidence (Hubel and Wiesel, 1959) supports this hypothesis. If this hypothesis is correct, it is likely that further work on FAEs determined by apparent size may help to throw light on the physiological mechanisms underlying size constancy, and some further experiments are suggested.     

Figural after-effects, retinal size, and apparent size

The results of earlier experiments on the question of whether figural after-effects are affected by apparent as opposed to retinal size are shown to be inconclusive. A new hypothesis is proposed namely that both factors may be responsible for producing figural aftereffects, and four experiments have been made to test it. Situations were used in which the apparent sizes of the figures were determined by the size-constancy effect. It was found that where retinal sizes of test and inspection figures are the same and apparent sizes are different, figural after-effects in the direction which would be predicted on the basis of apparent sizes are obtained. It was further shown that where retinal and apparent sizes are in conflict, whether a figural after-effect is seen or not, and the direction of the figural after-effect, depends upon the balance between these two factors.     

Psychophysics of lateral tachistoscopic presentation

Human visual performance depends upon the retinal position to which a target is delivered. A general finding is that performance measured in a variety of psychophysical tasks deteriorates as a target is presented to more eccentric retinal regions. One purpose of this paper is to describe differences between foveal and peripheral vision in a number of psychophysical tasks. A second purpose is to review studies which have attempted to account for the fall off in visual performance between central and peripheral target presentations. A third purpose is to consider the contribution of the periphery to perception since targets which are sufficiently large project not only on receptors in the fovea but also on those in the periphery. In addition, stimuli presented to the peripheral retina can influence the processing of a target presented to the central retinal region. A fourth purpose is to review studies which have attempted to compensate for foveal and peripheral differences by scaling the target in size or some other attribute in proportion to the cortical magnification factor. A final purpose of this paper is to consider whether the fovea and the periphery are specialized for different functions.     

Responses of schizophrenics and nonpatients to a tachistoscopic presentation of the Rorschach

Three groups of 36 subjects each, two of nonpsychiatric subjects and one of first admission schizophrenics, were administered the Rorschach tachistoscopically. Each group was subdivided into three subgroups to permit a variation in exposure times for the blots. Intervals of 200ms, 400ms, and 600ms were used; however, the differences in exposure times did not produce significant differences within any of the groups. Thus, the data were compared by groups. The results indicate no significant differences across the groups for accuracy of from (X + %). The schizophrenic group did give significantly more Special Scores related to cognitive slippage. They also gave a much higher proportion of pure form responses and substantially more card rejections than either of the nonpsychiatric groups. The results are discussed in the context of research on information processing and the early operations in the Rorschach response process.     

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-frame test (RIT) with either limited (tachistoscopic) or unlimited (Oltman’s, 1968, portable RFT) exposure time does not significantly affect the ranking of subjects. The underlying hypothesis 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 both 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 playa 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.     

eXpTools: A C++ class library for animation, tachistoscopic presentation, and response timing

The eXpTools Library is a general-purpose tool for developing psychological experiments that combine animation with tachistoscopic presentation. The library’s C++ classes and assembly language functions are specialized for the creation of visual response time experiments. Its use is limited to variants of standard, 16-color, VGA high-graphics modes. However, it extends the capabilities of these modes through bit-plane animation techniques and a new, nonstandard, high-resolution graphics mode that will work with standard VGA cards and register-compatible cards. These techniques make possible a powerful animation class for managing complex animation or tachistoscopic presentations consisting of hundreds or thousands of frames. The library also combines such features as page flipping, screen blanking, video-refresh synchronization, interrupt-driven millisecond timing, interrupt-driven keyboard response collection, graphics primitives, bitmaps, and screen fonts. Utilities allow for the conversion of PCX graphics files and the creation of new screen fonts from monochrome bitmap files. The technologies and techniques underlying the library are presented along with an example program.