Determinants of the rod and frame effect: The role of retinal size

In Experiment 1, base-out prisms were used to alter perceived size and distance to a luminous rod and frame while the retinal size remained unchanged. The rod-and-frame effect (RFE) was the same, whether the display was viewed directly or through the prisms. In Experiment 2, one large and one small rod-and-frame display were placed at distances such that they produced identical retinal angles. This was replicated at three different sets of distances. Perceived size and distance of the large and small frame of identical retinal angle interacted with the observation distance, such that at near distances the large frame was perceived as larger and farther than the small frame while, at far distances, both types of estimates converged to a constant value. In contrast, the RFE was identical for the large and small frames matched in retinal angle, but diminished with distance. In both experiments, the RFE varied precisely with variation in retinal angle. Implications of the role of retinal angle in the RFE and for the interpretation of individual differences were discussed.     

Visual angle and apparent size of objects in peripheral vision

Measurements of apparent size were obtained by distance adjustment of a peripherally viewed stimulus to produce a match to a foveally viewed standard. As eccentricity increased, the peripheral stimulus was adjusted at distances of progressively greater visual angle, indicating that a continuous diminution in apparent size occurs with increased eccentricity. This effect was found to be stable for several conditions of illumination and for changes in the light adaptive state of S. Apparent size diminution and apparent distance increase were also found for familiar objects viewed in an open field.     

Assessment of apparent length and angle explanations of the Poggendorff effect

Explanations of the Poggendorff effect were assessed by comparing the degree of angular distortion induced by modified and traditional configurations. Assimilation theory predicted that the traditional effect would be reversed in modified configurations. Analysis showed that the effect, although reduced in magnitude, was not reversed. Comparison of the degree of the effect induced by modified and traditional configurations indicated that a substantial portion of the Poggendorff effect was due to processing of areas between the long vertical lines of the display. This finding is not consistent with theories based on subjective distortion of angles. It was concluded that a theory of the Poggendorff effect must include processing of internal areas of the configuration.     

Apparent distance vs. apparent size as determiners of figural after-effects

Abstract.— Sutherland's (1954) much discussed experimental design was analysed in a new fashion. When the original experiment was repeated as such, the expected FAE was found. However, when the same IFs and TFs were presented in a vertical position, no significant FAEs were found. The results lend support to the interpretation presented earlier by Kolehmainen (1968): The FAE found by Sutherland was apparently due to an uncontrolled binocular disparity resulting in a different localization of stimulus figures in respect to the fixation point.     

The effect of frame figure type and frame size on the line and the circle Ponzo illusions

Abstract:   To examine the determinants of the Ponzo illusion, we compared the perceived size of lines and circles presented within three different frames: two converging lines, two circles, and two squares. Twenty stimulus figures, consisting of two types of objects (lines/circles) × three types of frame figures (Ponzo/circles/squares) × three sizes of lower frames (small/medium/large), and two control figures were presented on a personal computer display. Twelve students performed three measurements (upper-object/lower-object/illusion) for each stimulus figure using the method of adjustment. To analyze the relationship between single object perception and the Ponzo illusion, we compared the calculated values of overestimation magnitude differences between the upper and lower objects with the actual obtained illusion values of the six object-frame conditions. The calculated values of the circle and the square frame figures corresponded to the difference between the upper single object and the lower single object. In contrast, the results of the Ponzo figure need an additional factor to explain the differences between the obtained and the calculated values. These results indicate that two factors are involved in the Ponzo illusion: (a) the framing effect affects the perceived size of the individual single objects, and (b) the comparison factor affects the comparison process of the two objects within the converging lines.     

The gap between rod and frame influences the rod-and-frame effect with small and large inducing displays

The role of the spatial separation between the ends of a rod and a frame’s inner edge (gap) in modulating the rod-and-frame effect (RFE) has been studied here with frames subtending either large or small retinal angles. With a large frame, rod settings were always in the direction of frame tilt (direct effects) and varied inversely with gap size. With a small frame, rod settings were in the direction of frame tilt for tilts between 7.5° and 15°; with larger frame tilts, rod settings in the direction opposite that of the frame were observed (indirect effects). Increasing gap size produced a tendency toward negativity (away from frame tilt). Consequently, direct effects were larger for small gaps, while the opposite was true for indirect effects. Overall, these results point to the importance of gap size in modulating the RFE, for both large and small displays.     

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.     

The rod and frame effect and induced head tilt as a function of observation distance

Several experiments investigated the influence of a tilted luminous frame on the rod and frame effect (RFE) and on adjustments of the head to apparent vertical, while observation distance to the frame was varied between 1 and 5 m. Comparisons of repeated measures from the same subjects as well as between independent groups showed that distance was a highly effective variable. Both the RFE and the apparent head tilt varied inversely with distance to the frame, diminishing Lo zero at about 5 m. Since head settings were in the direction of the tilted frame, the latter may be inferred to have caused an induced head tilt (IHT) opposite in direction to the tilted frame, when the head was objectively upright. Issues discussed were the role of IHT in the RFE and factors underlying the role of distance in both phenomena.     

Observer pitch and roll influence: The rod and frame illusion

Observers misperceive the orientation of a vertical rod when it is viewed in the context of a tilted frame (therod and frame illusion, or RFI). The pitch and roll of the surrounding surfaces have independent influences on this illusion (Nelson & Prinzmetal, 2003). Experiment 1 measured the RFI when the pitch and roll of the floor that supported the observer was varied, and the observer was either seated in a chair or standing upright. There were additive influences of pitch and roll on the RFI of seated but not standing observers. Experiments 2 and 3 decoupled body roll and head roll in order to isolate the vestibular and proprioceptive contributions to these effects. The results are interpreted in support of a hierarchy of influence on the RFI: Visual input is given top priority, followed by vestibular input, and then proprioceptive input.     

A signal detection analysis of the rod and frame test

To help determine hut what Witkin’s Rod and Frame Test measures, the task was modified by presenting the luminous rod in one of two fixed positions, either vertical or not vertical, within a titled frame. S responded on a four-category scale representing his certainty that the rod was vertical Receiver operating characteristic (ROC) curves were calculated for each of 17 Ss and compared to traditional measures of titer field dependence-independence. The results showed that Witkin’s test is not contaminated to any great extent by response bias. However, the ROC analysis did reveal significant differences between field dependents and independents, not only in their sensitivity to verticality, but also in their- characteristic manner of responding.     

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.     

Picture perception is array-specific: viewing angle versus apparent orientation

The amount that a pictured lattice appears to be swung from its frame changes with subjects' viewpoint, in contrast with previous experiments using insufficient range of rotation. Also, this effect is shown to be independent of the physical slant of the picture surface, though not necessarily of border-shape information. Analysis of depicted headings which rotate with viewpoint, with respect to the picture plane, although the angle between these headings in virtual space hardly changes, relates these data to specific geometric properties of the perspective array as seen from the different viewpoints. Data show differential rotation of differently oriented features within a single depicted object, in a way that is dependent on task instructions. It is proposed that in picture perception, contradictory cues are resolved by combination.     

Shrinkage in the apparent size of cylindrical objects

A novel illusion in apparent size is reported. We asked observers to estimate the width and depth of vertically oriented elliptic cylinders depicted with texture or luminance gradients (experiment 1), or the height of horizontally oriented elliptic cylinders depicted with binocular disparity (experiment 2). The estimated width or height of cylinders showed systematic shrinkage in the direction of the gradual depth change. The dissimilarity of 2-D appearance amongst our stimuli implies a large variation in spatial-frequency components and brightness contrasts, eliminating the possibility that these parameters contributed to the illusion. Also, the mechanism inappropriately triggered by pictorial depth cues (eg size scaling) may be irrelevant, because the illusion was obtained even when binocular disparity alone specified the shape of the cylinders. The illusion demonstrated here suggests that our visual system may determine the size of 3-D objects by accounting for their depth structures.     

The relation between size and apparent heaviness

Attention, Perception, & Psychophysics - A formula for the size-weight illusion was derived from the Stevens and Rubin (1970) finding that heaviness functions form a family of power functions...     

Judgment of angle size: An experimental appraisal

Previous work on the estimation of angle size suggested that three factors play a significant part in the forming of an accurate estimation: the size of the angle, its orientation, and the mode in which the response is made. An examination of the judgment by 60 Ss of 12 angles under varied conditions of orientation, response mode, and cue was carried out with the result that the importance of size and orientation was confirmed. Despite an overall significant difference in estimation between response modes, there was no indication of a consistent effect across angles for the different modes. Predictions on the influence of orientation made by Fisher and Beery were tested, and while the former investigator was adequately supported, the latter was held to have reported results on a limited sample of angles which do not generalize to the wider range of angles used in the present study.