APPARENT SIZE AS A DETERMINER OF FIGURAL AFTER-EFFECTS. I

K olehmainen , K. Apparent size as a determiner of figural after-effects. I. Scand. J. Psychol ., 1968, 9, 230–236.—Apparent size as a determiner of figural after-effects (FAE) was studied by presenting the inspection figures in drawings which appeared three-dimensional because of gradient-effects. Significant FAEs were found. It is argued that apparent size does not determine FAE directly but an apparent decrement in the size of the test figure is connected to an after-effect in third-dimension.     

The distance gradient in the after-effect of kinaesthetic width judgement

The combined effects of inspection-time and interfigural distance on a kinaesthetic figural after-effect were determined. The figural after-effect was defined as the degree to which a 2-in. width appeared to shrink following prolonged inspection of larger widths. The inspection-widths were 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 in. and the inspection-times were 10 and 50 sec. A control group which did not inspect any widths was also employed. 156 subjects were tested. The results indicated that the classical non-monotonic relationship between interfigural distance and figural after-effect was not present. Instead, the figural after-effect increased as a negatively accelerated function of interfigural distance. Increasing inspection-time increased the asymptotic level of the figural after-effect. These results were interpreted in terms of the effects of anchors on judgements of magnitude.     

APPARENT SIZE AS A DETERMINER OF FIGURAL AFTER-EFFECTS. III

K olehmainen , K. Apparent size as a determiner of figural after-effects. 111. Scand. J. Psychol ., 1969, 10 , 71–73.—Two rectangles were presented as an inspection figure in a gradient drawing, one appearing to be behind the fixation point and the other in front of it, because of the gradient effect. Test figures (circles) appeared to differ in size after inspection of this pattern. It is argued that this result supports the explanation suggested for the results of the earlier experiments in the present series (1968) that size-changes of the test figures in this kind of situation are connected with an after-effect in the third dimension.     

On the figural after-effect

Two experiments were carried out on the figural after-effect. The first was intended to discover whether the figural after-effect did in fact take place with statistically significant universality. The method of scoring is relevant to the question of statistical significance, but at the best the figural after-effect appears to occur in only a slightly significant manner under the first conditions used. These involved the viewing of a single circle displaced to the left of a fixation point (the inspection-figure) and so placed that if it were superimposed on the second figure—which consisted of two squares on either side of the fixation-point—the circle completely encircled the left-hand square. The second figure is called the test-figure. The fixation point of the inspection-figure was fixated for 25 seconds with one eye, and then the test-figure was substituted and viewed with the opposite eye. A decision was then given by the observer as to the relative size of the squares. Eye-dominance did not appear to be connected with these after-effect processes.

In the second experiment, however, the statistical significance of the occurrence of the after-effects was undoubted. There were two changes in experimental conditions: the instructions to the observers were changed somewhat and a second circle was introduced into the inspection-figure. No difference of any kind was found to occur in the figural after-effect when the test-figure and inspection-figure were displaced horizontally and when they were displaced veitically, and there appeared to be a precisely opposite effect to that predicted when the test-figure and the inspection-figure were actually superimposed.

The most important finding was that, whereas in the first experiment the after-effect occurred with a frequency which was barely significant statistically, it occurred on every occasion under the different conditions of the second experiment.     

The subjective size of visual stimuli affects the perceived duration of their presentation

The perception of time spent looking at a stimulus is lengthened or shortened when its physical attributes, such as area, differ from those of a comparison stimulus. We measured the perceived presentation duration of a visual object whose apparent area was altered by the Ebbinghaus illusion while its physical size remained invariant, so that a central circle surrounded by larger inducers appeared smaller than a same-size central circle surrounded by smaller inducers. The results showed that the perceived duration of presentation for apparently larger circles was longer than that of apparently smaller circles, although the actual area remained invariant across all circles. We concluded that the time perception process receives input from later visual processing.     

An unusual case of after-imagery following fixation of an “imaginary” visual pattern

The case of a healthy normal subject is described in which negative after-images were reported to follow fixation of an “imaginary” pattern. The size of the after-image was measured at various distances and found to agree closely with the size of an after-image induced by fixation of a “real” visual pattern, and to conform roughly with Emmert's Law. No evidence for chromatic after-images was obtained. Two controls were conducted, one indicating that the results could not be attributed to after-images resulting from objective aids used to maintain an “imaginary” pattern of constant size; the other discounting the possibility of the subject's having guessed the correct values. Similar phenomena reported in the early literature are briefly mentioned, and some theoretical implications discussed.     

Perceived size of familiar objects and the theory of off-sized perceptions

In three experiments, I examined the claim (Gogel, 1969; Gogel & Newton 1969)that familiar objects viewed under reduced stimulus conditions frequently appear to be off-sized (i.e., larger or smaller.than normal). In Experiments 1 and 2, I presented images ofdifferent familiar objects, one at a time, at distances of .1. and 2 m from the observers. The images were normal-, large-, or small-sized versions of familiar objects, and the observers judged the perceived size of each object rela.tive to its familiar normal size. In Experiment 3, I presented normal-, large-, and small-sized versions of thesame familiar object at physical distances of 1 and 2 m. The pattern of size results was similar across the three experiments. In general, normal-sized objects appeared normal to small-sized at the 1-mdistance and small-sized at the 2-mdistance; small-sized objects appeared small-sized at the 1-m distance and even smaller at the 2-m distance; and large-sized objects appeared normal- to large-sized at the 1-m distance and normal- to small-sized at the 2-m distance. The distance results of Experiment 3 indicated that familiar size was an effective determinant of reported distance. These results are consistent with Gogel’s theory of off-sized perceptions and, more generally, with the claim that familiar size is not an important determinant of perceived size.     

MEASUREMENT OF THE INTENSITY OF AN UNDERLYING FIGURAL PROCESS: A methodological study

K ünnapas , T. M. Measurement of the intensity of an underlying figural process. A methodological study. Scand. J. Psychol ., 1961, 2 , 174–184.—A method is proposed for studying the intensity of the figural process underlying the well-known phenomenon of figural fluctuations. A metric model is presented according to which a measure of the intensity of the underlying process is obtained in units of dispersion. The model is illustrated by an experimental example. An equation is given which is analogous to that of the damped harmonic vibration. Four parameters are involved in this equation. A technique for determining the parameters is developed. Very good agreement between theoretical and empirical scale values demonstrates the applicability of the proposed method.     

Exploring the relationship between perceived Action-Outcome distance and Agency: Evidence from temporal binding

Intentional actions are usually accompanied by a sense of agency (SoA), along with a perceived shortening of action-outcome intervals known as the intentional binding (IB) effect. This is at least partly associated with the perceived strength of action-outcome relationships, which have been described in terms of distance (e.g., a ‘distancing effect’). Given that actions in the modern world are increasingly distant from their outcomes, the current study aimed to explore the effect of perceived spatial distance on the strength of IB. Participants voluntarily triggered, or passively observed, a circle on a background that was either flat or appeared three-dimensional, and estimated action-outcome delays. Depth cues modified the circle’s perceived distance while the circle itself did not change. When viewed on a forced-perspective background, interval estimates increased with apparent distance, but only when outcomes were caused by intentional actions. This suggests that agency is reduced for outcomes that appear further away.     

A further investigation of apparent size and retinal size as determinants of the figural after-effect

A figure which is more distant from the eye than another but subtends the same visual angle is usually seen as the larger. This phenomenon is called perceptual size constancy. Experiments have been reported which show that sometimes the apparent and sometimes the retinal sizes of the stimulus figures determine the direction of the figural after-effect. These experiments are reviewed and two further experiments are reported. In the first experiment two types of stimulus figure (discs and annuli) which subtended a visual angle of 1° 36' resulted in figural after-effects, the direction of which would have been predicted by the retinal sizes of the figures. In the second experiment larger figures were used which subtended a visual angle of about 4° and which were the same as those used by Sutherland (1954). In this experiment the after-effects were generally in a direction which would have been expected if apparent size determined the direction of the after-effect. In the interpretation of the results attention is drawn to the “Central Tendency Effect” which has been observed in size judgements of stimulus figures of varying size. Two hypotheses are suggested; one is that the true figural aftereffect has been obscured by the “Central Tendency Effect” in successive judgements, and the other is that time error in successive judgements of size is essentially a figural aftereffect. Some supportive evidence for the latter hypothesis is reported. It is concluded that apparent size is not a critical determinant of the figural after-effect.     

The role of suggested size in distance responses

A number of studies have concluded that suggested size can modify perceived size, as indicated by the effect on perceived distance. At least this effect seems to occur when verbal reports are used as the measure of the judged distance of the target. The present study supports a different explanation of this phenomenon. It is hypothesized that suggested size can result in the judgment that the target is larger or smaller than normal (an off-sized judgment) where normal is specified by the suggested size. Because the observer expects that a target judged as a small or large off-sized object must be at a greater or lesser distance, respectively. than its perceived distance, the off-sized judgment can provide a cognitive modification of reported distance. This explanation was tested by measuring the perceived distance of targets using a procedure (called the head motion procedure) that, in contrast with verbal reports of distance, is very unlikely to be influenced by off-sized judgments. Measures obtained with the head motion procedure, unlike those obtained from verbal reports, did not change with changes in the suggested size. It is concluded that the size suggestions had a cognitive, not a perceptual, effect on responses to the distance (and size) of the targets.     

FIGURAL REVERSAL RATE AND PERSONAL TEMPO

K ünnapas , T. Figural reversal rate and personal tempo. Scand. J. Psychol ., 1969, 10, 27 –32.—Thirty subjects participated in a figural fluctuation experiment. The same subjects were given five perceptual tests representing personal tempo. Coefficients of correlation between figural reversal rate and personal tempo were generally positive but low. Three main factors were found to account for the variability of perceptual activity: ( a ) perceptual fluency, (b) decision speed, and ( c ) immediate perceptual memory.     

The nature of adaptation in distance perception based on oculomotor cues

In previous work by the senior authors, brief adaptation to glasses that changed the accommodation and convergence with which objects were seen resulted in large alterations in size perception. Here, two further effects of such adaptation are reported: alterations in stereoscopic depth perception and a change when distance is represented by a response of S’s arm. We believe that the three effects are manifestations of one primary effect, an alteration of the relation between accommodation and convergence on the one hand and the distance they represent in the nervous system (registered distance) on the other. This view was supported by the results of two experiments, each of which demonstrated that the alterations in stereoscopic depth perception could be obtained after adaptation periods which had provided no opportunity to use stereoscopic vision, and that the adaptation effect was larger for depth perception than for size perception when it was obtained under the same conditions; the latter finding was expected if both effects resulted from the same change in registered distance. In three of the five experiments here reported, the variety of cues that could represent veridical distance during the adaptation period was limited. In one condition of adaptation, only the pattern of growth of the retinal images of objects that S approached and the kinesthetic cues for S’s locomotion served as cues to veridical distance. In two other conditions S remained immobile. In one of these, only the perspective distortion in the projection of the scene that S viewed mediated veridical distance, and in the other one familiar objects of normal size were successively illuminated in an otherwise totally dark field, conditions from which opportunities to use stereoscopic vision were again absent. After exposure to each of these adaptation conditions, adaptive changes in perceived size and larger ones in perceived stereoscopic depth were obtained. Because we found that familiar size may serve as the sole indicator of veridical distance in an adaptation process, we concluded that it can function as a perceptual as distinguished from an inferential cue to distance.     

Temporal organization of pattern structure

Two pattern reproduction experiments examined the relations among the figural goodness of a pattern, the organization of two parts within the pattern, and the interpart interval (ISI), which ranged from 40 to 200 msec. If the parts contained connected line segments, performance was slightly better (3%-5% gain in accuracy) at a 40-msec ISI than at a 200-msec ISI. If the parts contained unconnected line segments, reproduction accuracy of the first part declined sharply between 40 and 200 msec. These results were interpreted by assuming that the parts were perceived as a single whole pattern at a 40-msec ISI but as two separate patterns at a 200-msec ISI. One surprising finding, the lack of an interaction between figural goodness and ISI, was explained in terms of a response bias in favor of figural good patterns. A secondary manipulation revealed that a part was more accurately reproduced in a good figure context than in a poor figure context but was most accurately reproduced when it appeared alone.     

Selective attention and relevance-irrelevance in recall

Abstract.— Recall of relevant and irrelevant items was examined under different types of set, where selection was procured either by a figural or a cognitive attribute of the items. Letters and digits were differentiated by their colour or position (S-set), or by their mutual class (R-set). Recall of irrelevant items proved consistently poorer with selection based on S-set than on R-set. the effect beeing enhanced, the greater the number of items involved. Response latency increased with number of items, being greatest under R-set. The differentiation between relevant and irrelevant categories thus appeared more effective with selection procured by figural attributes, which suggests different levels of information processing of these categories under the two types of set.     

Mapping the perceptual structure of rectangles through goodness-of-fit ratings

Three experiments were carried out to investigate the internal structure of a rectangular frame to test Arnheim's (1974 Art and Visual Perception, 1988 The Power of the Center) proposals about its 'structural skeleton'. Observers made subjective ratings of how well a small probe circle fit within a rectangle at different interior positions. In experiment 1, ratings of 77 locations were highest in the center, decreased with distance from the center, greatly elevated along vertical and horizontal symmetry axes, and somewhat elevated along the local symmetry axes. A linear regression model with six symmetry-related factors accounted for 95% of the variance. In experiment 2 we measured perceived fit along local symmetry axes versus global diagonals near the corners to determine which factor was relevant. 2AFC probabilities were elevated only along the local symmetry axes and were higher when the probe was closer to the vertex. In experiment 3 we examined the effect of dividing a rectangular frame into two rectangular 'subframes' using an additional line. The results show that the primary determinant of good fit is the position of the target circle within the local subframes. In general, the results are consistent with Arnheim's proposals about the internal structure of a rectangular frame, but an alternative interpretation is offered in terms of the Gestalt concept of figural goodness.     

ROD VISION AS CHROMATIC VISION

S tabell , B. Rod vision as chromatic vision. Scand. J. Psychol ., 1968, 9, 282–288.—It was found (I) that the smallest quantity of light of pre-stimula-tion which produces color upon test-stimulation, stands in unique relation to the intensity of the specific threshold, and (2) that the size of the pre-and test-stimulation fields may affect the duration of the after-image. The results are judged to indicate that pre-stimulation of cones creates the disposition for the color-related response, and that the color-related response is generated centrally to the photochemical systems of the receptors.     

Perceived size and distance as a perceptual conflict between two processing modes

Three different sized squares were successively presented at the same physical distance under three observational conditions which provided different information about distance in the visual field. The 60 observers in each observational condition were asked to give verbal absolute judgments of perceived size and perceived distance for each of the squares. The results showed that in a full-cue situation a ratio of perceived absolute sizes is equal to that of the corresponding visual angles, with perceived distances appearing equal to each other; in a reduced-cue situation an object of smaller perceived size is judged to be farther away than one of larger perceived size, with the observers tending to assume the two objects as the same object or identically sized objects. These results were analyzed in terms of the perceptual conflict between primary perception and secondary perception.     

Is size perception based on monocular distance cues computed automatically?

The study reported here examined whether size perception based on monocular distance cues is computed automatically. Participants were presented with a picture containing distance cues, which was superimposed with a pair of digits differing in numerical value. One digit was presented so as to be perceived as closer than the other. The digits were of similar physical size but differed in their perceptual size. The participants’ task was to decide which digit was numerically larger. It was found that the decision took longer and resulted in more errors when the perceptual size of the numerically larger digit was smaller than the perceptual size of the numerically smaller digit. These results show that perceived size affects performance in a task that does not require size or distance computation. Hence, for the first time, there is empirical support for the working assumption of the visual perception approach that size perception based on monocular distance cues is computed automatically.     

Pigeons perceive the Ebbinghaus-Titchener circles as an assimilation illusion

A target circle surrounded by larger "inducer" circles looks smaller, and one surrounded by smaller circles looks larger than they really are. This is the Ebbinghaus-Titchener illusion, which remains one of the strongest and most robust of contrast illusions. Although there have been many studies on this illusion in humans, virtually none have addressed how nonhuman animals perceive the same figures. Here the authors show that the Ebbinghaus-Titchener figures also induce a strong illusion in pigeons but, surprisingly, in the other direction; that is, all five successfully trained pigeons judged the target circle surrounded by larger circles to be larger than it really is and vice versa. Further analyses proved that neither the gaps between target and inducer circles nor the cumulative weighted surface of these figural elements could account for the birds' responses. Pigeons are known to show similarities to humans on various cognitive and perceptual tasks including concept formation, short-term memory, and some visual illusions. Our results, taken together with pigeons' previously demonstrated failure at visual completion, provide strong evidence that pigeons may actually experience a visual world too different for us to imagine.