bluuebunny/crossref_metadata_2025 huggingface dataset:
Human Perception of Homogeneous Dot Patterns
Authors: O'Callaghan J F
Published: January 2007

Experiments were conducted to ascertain human performance at clustering relatively homogeneous dot patterns. Two methods for clustering a rectangular array of dots into two halves were studied: one increased the separation between the left and right halves, and the other increased the density of one of the halves. Significant effects were found for array height on the perception of ‘separation’ patterns, and for overall dot density on the ‘density’ patterns.

The results indicate that global properties of dot patterns affect the immediate perception of clusters, and consequently attempts to simulate human perception must incorporate the processing of such global properties. The results also indicate that different perceptual processes operate on dot proximity in perceiving the two kinds of pattern. It is suggested that these processes are in fact complementary: one detects perceptual edges, while the other groups areas of similar dot density.
An Observation concerning the Preferred Perception of the Visual Horizontal and Vertical
Authors: Davidoff J B
Published: January 2007

It was noticed in a drawing consisting of many equally dark lines that horizontal and vertical lines were preferred perceptually. With head tilt, it was lines on the horizontal and vertical with respect to the head tilt that were now preferred.
Movement Aftereffects Contingent on Binocular Disparity
Authors: Anstis S M , Harris J P
Published: January 2007

Five subjects adapted for 30 min to a textured disc lying in front of the fixation point with 0·1 deg(1) crossed disparity, which rotated clockwise at 4 rev/min, alternating with a disc behind the fixation point, with 0·1 deg of arc uncrossed disparity, which rotated anticlockwise. A stationary test field then appeared to rotate anticlockwise when it lay in front of the fixation point, and clockwise when it lay behind. Conversely, a test field in the plane of fixation briefly appeared to lie a few millimetres behind the fixation plane when it rotated clockwise, and in front when it rotated anticlockwise.

The movement aftereffect contingent on disparity reappeared each time the test disparity was reversed, but the total duration of each successive aftereffect in the series decreased exponentially with elapsed time. Movement aftereffects contingent on disparity were very much stronger than those contingent on colour and won out over them when disparity was pitted against colour.
Pair Comparison and Ascending Series NaCl Thresholds: Criterion and Residual Effects
Authors: O'Mahony M , Ivory H , King E
Published: January 2007

Ascending series detection and recognition thresholds, both with and without interstimulus water rinses, and pair comparison thresholds, with varied presentation order, were measured for NaCl. Thresholds were measured in situ against a normal salivary background and also after rinses with 60 mM and 1 M NaCl. Predicted changes in the level of adaptation of the taste receptors, due to NaCl concentration changes in the mouth, were seen to vary the measured thresholds. Ascending series thresholds without interstimulus rinses were highest of all, although they were reduced by rinsing. The order of presentation in pair comparison tests was seen to vary thresholds in a manner predicted by proposed adaptation levels. Effects were also noted which were due to criterion definition and language. The trends found in the present experiments were also found in the literature.
Atrophy of Retinal Ganglion Cells after Removal of Striate Cortex in a Rhesus Monkey
Authors: Cowey A
Published: January 2007

The retinal ganglion cells were counted in a rhesus monkey from which the striate cortex had been removed 8 years earlier, and the results compared with those obtained previously with the eyes of normal monkeys. About 80% of the ganglion cells within 10 degrees of the fovea were missing. Peripherally their density was unaffected. The ganglion cell layer of the entire retina resembled the peripheral retina of a normal monkey, and this result helps to explain the remarkable nature of the animal's vision.
The Young Child's Discrimination of Obliques
Authors: Harris P L , Le Tendre J B , Bishop A
Published: January 2007

The five-year old child, in common with other species, has difficulty in remembering the slope of an oblique stimulus, but not of a horizontal or vertical stimulus. Two experiments are described. The first shows that the relative difficulty with obliques is not caused by the child remembering orientation in relation to background features. The second shows that the five-year old can remember obliques, but that this memory is fragile.
Diphasic and Polyphasic Temporal Modulations Multiply Apparent Spatial Frequency
Authors: Virsu V , Nyman G , Lehtiö P K
Published: January 2007

The effects of diphasic and polyphasic flicker on apparent spatial frequency were studied in several experiments through simultaneous spatial-frequency matches. In diphasic flicker the spatial phase of a sinusoidal grating alternated between two values in a counterphase fashion, and in polyphasic flicker the spatial phases of gratings were varied discretely in time in a variable number of steps. Both forms of flicker increased the apparent spatial frequency at low temporal frequencies, in the same manner as low-frequency monophasic flicker has been found to do. At high temporal frequencies, diphasic flicker doubled the apparent spatial frequency, as reported by Kelly (1966). We found that through high-frequency polyphasic flicker the spatial effect that Kelly mentions can be generalised to spatial frequency multiplication: polyphasic flicker produces not only the apparent second harmonic but also the third and the fourth harmonic, depending on the phase parameters. A numerical analysis showed that the spatial high-frequency effects can be explained through temporal integration of nonlinearly filtered input signals if a value of 200 td(1) is assumed for the nonlinearity constant in

[Formula: see text]

where B( I) is the brightness, I is the retinal illuminance, K is a scale constant, and I½ is the constant of nonlinearity. A minimum value of 60 ms had to be estimated for integration time. An investigation of the integration time with diphasic flicker indicated that spatial integration time decreases when the level of light adaptation increases, and that the integration time for spatial effects is longer than for flicker fusion. The spatial effects of low-frequency and high-frequency flicker differ in so many respects that different neural processes have to be postulated for their explanation.
Speculations on a Model of Prism Adaptation
Authors: Welch R B
Published: January 2007

Arguments and evidence are presented that prism adaptation results in a third end state in addition to the ‘traditional’ components of ‘proprioceptive shift’ and ‘visual shift’. That is, under certain conditions (most importantly, ones involving error-corrective feedback), exposure to prism-displaced vision induces a motor-learning component, referred to here as an ‘assimilated corrective response’. Thus the postexposure error in target pointing, the ‘negative aftereffect’, is postulated to be the algebraic sum of proprioceptive shift, visual shift, and an assimilated corrective response—at least in certain situations. Support for the existence of this third component as a form of learning is seen in the fact that it occurs primarily when prism exposure involves target-pointing experience, and that it is apparently subject to the effects of some ‘learning variables’.
Dark Adaptation and Short-Wavelength Backgrounds Decrease Perceived Size
Authors: Virsu Veijo , Vuorinen Risto
Published: January 2007

The effects of background luminance, contrast, and background wavelength on the perceived size of small line figures were studied at mesopic levels of light adaptation. Perceived size diminished at low levels of background luminance. The effect disappeared at high levels of luminance. Perceived size of luminous circles increased as a logarithmic function of background luminance when the background intensity did not exceed 25 td(1). The strength of the size effect decreased as a function of circle diameter from 0·125 to 2 deg of visual angle(2). Perceived size of small luminous circles, subtending less than 0·5 deg, also increased as a function of contrast at low values of contrast but at very high values of contrast there was a decrease in perceived size. Background luminance had the same effect on the perceived size of circles as on the perceived size of spatial cycles in gratings.

Control experiments led to the conclusion that dark adaptation is the primary source of the size effects. The main evidence for this conclusion was obtained from a demonstration that the same background luminance produced either an increase or a decrease in perceived size, depending on the adaptational state of the eye. It was also found that a shift from cone vision to rod vision contributes to the effects, for a stimulus looked smaller on a short-wavelength background than on a long-wavelength background. The size effects can be predicted from the changes of receptive-field properties of single neurones under corresponding conditions of stimulation, if it is assumed that the perception of size is mediated by size-specific channels formed of single neurones. Stimulation that leads to an activation of small receptive fields appears to indicate to the brain the presence of small retinal images. If small receptive fields are experimentally made responsive to larger retinal images, an underestimation of size results.
Perceiving the Language of Films
Authors: Frith Uta , Robson Jocelyn E
Published: January 2007

Children appear to be familiar with the language of film makers or at least to perceive and remember films less well when the rules of this cinematic language are broken. In this experiment a simple action sequence filmed from a static viewpoint was made up into two films of four shots. One film was edited according to the rules of directional continuity specified by Hollywood cinema, that is the four shots were presented so as to preserve the subject's direction of movement across cuts. The other film was edited disregarding these rules. Apart from this difference both films were identical. Children aged seven, nine, and thirteen years watched either of these films and reconstructed the action using pictures representing the four shots. The children who saw the conventional version were better able to reconstruct what they had seen than those who saw the unconventional version.
Violations of Symmetry and Repetition in Visual Patterns
Authors: Bruce Vicky G , Morgan Michael J
Published: January 2007

Observers were asked to detect small violations in otherwise left-right symmetric or repeated line patterns. The decision time for symmetric patterns tended to be shorter than for repeated patterns, confirming an intuitive impression that symmetry is a very easily extracted feature, even of otherwise random patterns. The importance of the pattern midline in determining the salience of symmetry was investigated by systematically controlling the position of the violations in the patterns. Small departures from symmetry near the midline were much easier to detect than the same violations in a repeated pattern, but there were no differences where the violation was at the edge of the pattern. The salience of symmetry seems to a considerable extent to depend upon the ease of comparing spatially-contiguous elements near the midline of the pattern. However, both symmetry and departures from it are easier to detect than repetition, even when the nature of the violation is random.
Predictions of U-Shaped Backward Pattern Masking from Considerations of the Spatio-Temporal Frequency Response
Authors: Breitmeyer Bruno G
Published: January 2007

The threshold detectability of a briefly presented target stimulus consisting of a vertical sinusoidal grating was affected not only by the spatial frequency content of an equally briefly presented, two-octave-wide masking noise, but also by the time interval separating the onsets of the target and its mask. Over a range of stimulus onset asynchronies, in which the mask onset either preceded, coincided with, or followed the target onset, a mask with a low spatial frequency content had its greatest masking effect on a high spatial frequency target grating when the mask followed the target by 120–180 ms. When the mask had a high spatial frequency content and the target was of low spatial frequency, or when the target was entered on the mask frequency band, optimal masking effects occurred when the onsets of the mask and target coincided. The results are discussed in relation to previous masking studies, particuarly those in which U-shaped backward pattern masking functions are obtained.
Prism Adaptation to Moving and Stationary Target Exposures
Authors: Wallace Benjamin
Published: January 2007

The magnitude of proprioceptive adaptation and visual adaptation to prism displacement was assessed for various target conditions during either observed, active or passive arm movements. Active arm movement was found superior to passive arm movement in the production of proprioceptive aftereffects and visual aftereffects. In addition, observation of a stationary target or a moving target during prism exposure produced significant proprioceptive adaptation for a passive arm viewing condition while enhancing such adaptation magnitude for an active arm movement situation. With no target present during prism exposure, significant proprioceptive adaptation was only found with active movement. The greatest visual aftereffect was produced when a moving target was observed during prism exposure. The results are interpreted in terms of an information-availability model of perceptual adaptation.
Riemannian Geometries of Variable Curvature in Visual Space: Visual Alleys, Horopters, and Triangles in Big Open Fields
Authors: Battro Antonio M , Netto Scipione di Pierro , Rozestraten Reinier J A
Published: January 2007

Luneburg's model for computation of the curvature K of visual two-dimensional space (horizontal visual surface) was tested with equidistant and parallel alleys in large open spaces. Forty-six subjects used stakes to produce 406 experimental alleys of variable sizes (from 5 × 1 to 240 m × 48 m). The results show that, contrary to results obtained under laboratory conditions with small alleys and light spots, the individual curvature of visual space does not have a negative constant value. K varies in the interval −1 to +1 in ninety computed settings: K ≥ 0 ( N = 38); K < 0 ( N = 52). Therefore the Lobachevskian geometry currently attributed to visual space ought to be replaced by a Riemannian geometry of variable curvature. Moreover K is an individual function dependant on the size of the alley (distance from the subject), and visual perception would be better understood as scale-dependent. Independently of Luneburg's model we have tested the constancy of the curvature hypothesis in experiments with horopters and visual triangles. The results obtained invalidate Luneburg's hypothesis also.
Infants' Reaction to Changes in Orientation of Figure and Frame
Authors: Wiener Kenneth , Kagan Jerome
Published: January 2007

Five groups of five-month-old infants observed the same horizontal arrangement of a three-element stimulus placed in a rectangular frame during a series of habituating trials. These trials were followed by either (i) additional exposure to the familiarized standard, (ii) a triangular rearrangement of the three stimulus elements, (iii) oblique rotation of the three elements, (iv) oblique rotation of the three elements and the frame, or (v) oblique rotation of the frame alone. The infants were responsive to all changes in the spatial arrangement of the three elements and to the rotation of the frame, but were less responsive to the change in the frame. The two effects were not additive.
Stereoscopic Discrimination in Infants
Authors: Atkinson Janette , Braddick Oliver
Published: January 2007

The ability to make discriminations of binocular disparity was investigated in 2-month-old infants by two methods: (a) fixation preference between patterns differing in the disparity they contained, and (b) recovery from habituation of high-amplitude sucking when there was a change in disparity in the visual reinforcer. The stimuli were random-dot stereograms. The results for both methods indicated that at least some infants of this age could perform stereoscopic discriminations and that both techniques were feasible for development for longitudinal studies of stereoscopic vision.
Problèmes Posés Par La Reproduction de Modèles Spatiaux Chez Des Enfants Aveugles: Une étude Expérimentale
Authors: Robin Monique , Pêcheux Marie-Germaine
Published: January 2007

The ability to reproduce two-dimensional and three-dimensional spatial models was tested in eighteen blind children, aged seven to eleven with two tasks (block design test and stick test). Performances and strategies were compared with those of seeing children. The results failed to show any important specific errors in blind children; despite blindness some children reached levels of performance as good as those of seeing children, while others completely failed to follow instructions. All such effects were independent of age. The problem is raised of the psychological conditions of space representation, independent of the afferences through which space is perceived.
How Monkeys Acquire a New Way of Seeing
Authors: Humphrey Nick K , Keeble Graham R
Published: January 2007

In an experiment on perceptual learning, monkeys were given the opportunity to watch on television the ‘private behaviour’ of another monkey (which did not know it was being watched). The subjects were shown monkey X for twenty sessions in a row, followed by monkey Y for twenty sessions, followed by monkey X again for twenty sessions. The subjects' ‘interest’ in the stimulus monkey remained roughly level within each block of twenty sessions, but increased in a step-like way at the changeover from X to Y, and again from Y to X. These results are interpreted as evidence that the subjects gained little or no extra insight into the nature of private behaviour through watching the same monkey in successive sessions; the critical factor in their perceptual education was the comparison between one monkey's behaviour and another's.
Pigeons Learn the Concept of an ‘A’
Authors: Morgan Michael J , Fitch Martin D , Holman John G , Lea Stephen E G
Published: January 2007

Pigeons learned to discriminate between ‘A’s and ‘2’s in eighteen different typefaces. They subsequently showed excellent transfer to twenty-two typefaces that they had not previously seen; one pigeon was tested with handwritten letters and responded correctly to them also. Pigeons' responses to ‘A’s and ‘2’s with parts removed suggested that their performance was controlled by several features, none of which alone could be considered necessary or sufficient. A test in which birds were shown other letters of the alphabet supported this conclusion. It appears that the original discrimination was learned as what Ryle calls a ‘polymorphous concept’.
Binocular-Disparity-Dependent Upper—Lower Hemifield Anisotropy and Left—Right Hemifield Isotropy as Revealed by Dynamic Random-Dot Stereograms
Authors: Julesz Bela , Breitmeyer Bruno , Kropfl Walter
Published: January 2007

Dynamic random-dot stereograms devoid of all monocular depth cues were used to measure the limits of temporal and spatial resolution in the center of the visual field. The temporal durations for detecting a small, briefly presented test square of different binocular disparity than the surround varied as a function of its location and binocular disparity. The test squares presented in the upper hemifield were detectable at consistently shorter durations than those presented in the lower hemifield for a surround disparity which was uncrossed relative to the fixation marker. For crossed surround disparity this preference reversed, resulting in a superiority of the lower hemifield. The anisotropy diminished for zero surround disparity. No such anisotropy was found when left and right visual hemifields were compared. It was also shown that this upper—lower temporal anisotropy (and left—right isotropy) is paralleled by a similar disparity-dependent upper—lower anisotropy (and left—right isotropy) in spatial resolution. Introduction of monocular clues into the stereograms tended to eliminate the anisotropics. This implies that the anisotropics reflect the spatiotemporal properties and distribution of binocular disparity detectors in the human cortex and result in a tilted surface that pivots around the horizontal midline in the space of binocular depth perception.
Aristotelianism, Newtonianism and the Physics of the Layman
Authors: Shanon Benny
Published: January 2007

Written and visual surveys were administered in order to assess people's models of the physical world. A comparison was made between scientific theories and the layman's philosophy of nature on the one hand, and between people's conceptions and perceptions on the other hand. The findings suggest that there are discrepancies on both levels: people do not conceive the world as physicists do, and their conceptions are different from their perceptions.
Did Ptolemy Understand the Moon Illusion?
Authors: Ross Helen E , Ross George M
Published: January 2007

Ptolemy is often wrongly credited with an explanation of the moon illusion based on the size-distance invariance principle. This paper elucidates the two Ptolemaic accounts: one in the Almagest, based on atmospheric refraction, and the other in the Optics, based on the difficulty of looking upwards. It is the latter passage which has been thought to refer to size-distance invariance, but it is more probable that it refers to the idea that the visual rays are diminished by the force of gravity (i.e. that the retinal image is reduced in size). Alhazen was probably the first author to explain the illusion by the size-distance invariance principle, and Roger Bacon the first to explain the enlarged apparent distance of the horizon by the presence of intervening objects. Della Porta was the first to credit Ptolemy with these explanations, and this mistake was repeated by many subsequent authors.
A Figure-Density Hypothesis and Illusory Contour Brightness
Authors: Kennedy John M , Lee Henry
Published: January 2007

Perceived figures tend to have surface colour and to be comparatively dense in texture and saturated. These figure characteristics are found in many of the illusory contour figures examined heretofore but new figures presented here do not conform to these characteristics. Consequently, rather than explain subjective brightness effects as offshoots of figural processes, it may be better to begin with concepts of local brightness effects induced by the display, which are made perceptually effective when grouped by the eye.
How Good a Bet is Good Form?
Authors: Perkins David N
Published: January 2007

‘Good form’ theories of perception leave some latitude concerning how casually or cautiously order is imposed on the stimulus. Exploring this issue, the present experiment introduced a series of figures admitting up to three alternative ‘good’ readings. Eight college students estimated two angles in each of fifty-six pictured spatial forms. Theory predicted that geometrical regularities of rectangularity and symmetry would dominate their estimates. But a regularity would rarely appear when inconsistent with projective geometry and the given figure. The accuracy of subjects' estimates was also assessed. The results confirmed the hypotheses at high significance levels, arguing that such figures are interpreted through an order-imposing process restrained by projective geometry, and that subjects could make roughly accurate estimates based on the imposed order. Parallels with computer scene analysis are discussed. It is concluded that perceptual presumption of certain ‘good forms’ runs little risk of misinterpreting the stimulus.
Facilitation of Stereopsis from a Large Disparity Random-Dot Stereogram by Various Monocular Features: Further Findings (A Short Note)
Authors: Saye Ann
Published: January 2007

This experiment examined the effects of adding five different kinds of prominent monocular features to a large-disparity random-dot stereogram. It was found that features which enclosed the disparate area produced the shortest initial perception times for fusion. The longer initial perception times for stimuli containing features without this enclosing property are explained in terms of less-helpful guidance of saccadic eye movements prior to the establishment of fusion. Subsequent reductions in perception times for these latter stimuli could be due to perceptual learning within the eye movement control system.
Do Monkeys' Subjective Clocks Run Faster in Red Light than in Blue?
Authors: Humphrey Nicholas K , Keeble Graham R
Published: January 2007

When monkeys are given control of the illumination in a testing chamber, it has been found, under three conditions, that they spend less time with red light than with blue. But the results cannot easily be explained in terms of ‘preference’. Rather, the results suggest that monkeys judge ‘subjective time’ to pass nearly twice as fast in red light as in blue.
Serial Adaptation to Conflicting Prismatic Rearrangement Effects in Monkey and Man
Authors: Flook Jennifer P , McGonigle Brendan O
Published: January 2007

Seven adult male squirrel monkeys adapted successfully to prisms displacing in equal and opposite directions. After protracted training under certain conditions, they succeeded in conserving adaptation to both prisms without benefit of readaptation trials. Results obtained with thirty-six undergraduates under similar conditions of test (although for a much shorter period) are also reported.
Organizing the Properties of Impossible Figures
Authors: Cowan Thaddeus M
Published: January 2007

The empirical study of impossible figures requires that independent variables be well-specified. This paper provides an aid for such a task by developing a classification system which partitions cornered torus figures into meaningful subsets. These can be used to identify both formal and psychological properties of known as well as unknown possible and impossible figures in much the same manner as with the periodic table of chemical elements. The classification is polytopic (four dimensional) and is formally, not empirically, derived. Coherent three-dimensional and two-dimensional forms of the system are possible without loss of information.
Auditory—Visual Interactions and the Correspondence between Perceived Auditory Space and Perceived Visual Space
Authors: Regan David , Spekreijse Henk
Published: January 2007

Changes in the physical rate of a clicking or fluttering sound caused changes in the rate at which a simultaneously viewed light appears to flicker, even though the physical flicker rate remains constant. Perceived flicker rate increases in response to a rate of change of flicker frequency, and this auditory ‘driving’ does not depend on whether the auditory and visual sources have the same location. Visual evoked potentials do not correlate with ‘driving’. Thus, the effect of auditory flutter upon perceived visual frequency is not due to the properties of Morrell-type bimodal neurons, nor does it reflect the activities of neurons responsible for maintaining correspondence between perceived auditory space and perceived visual space. The effect is possibly due to modification of a subjective criterion rather than, as previously suggested, to the entrainment or time-locking of physiological signals in the visual pathway.
The Effects of Temporal Modulation on the Oblique Effect in Humans
Authors: Camisa John M , Blake Randolph , Lema Sandra
Published: January 2007

Contrast thresholds were measured for vertical and oblique grating patterns. As shown previously, at higher spatial frequencies sensitivity for vertical is much greater than that for oblique. Present results show that this difference in sensitivity is found only with low rates of temporal modulation; with higher temporal frequencies this orientation difference disappears. Moreover, when contrast thresholds are based on the perception of flicker, vertical and oblique sensitivities are essentially identical even at low flicker rates. These results indicate that the so-called ‘oblique effect’ is confined to mechanisms with poor temporal resolving power, probably the sustained channels which have been studied psychophysically and neurophysiologically by others.
Judgemental Criteria and the Perception of Structure
Authors: McGonigle Brendan O , Jones Barry T
Published: January 2007

We repudiate Dodwell's claim that his relational model is predictively more accurate than our Garner-based treatment of AT. We claim instead, that his case is based on a fundamental misunderstanding of the essentials of Garner's complex thesis, together with a misreading of our own report. Rather than accept his notion of a single continuum of salience as providing for the genesis of structure, we argue instead that his ‘single continuum’ compounds and confounds at least two continua which may be understood only where the criteria of judgement are made explicit.
A Halo Visual Illusion
Authors: Rubin David C , Rebson Daniel J
Published: January 2007

A visual illusion consisting of transparent halos extending beyond the boundaries of rotating discs is reported. The effect can be obtained by rotating a variety of black-and-white discs at moderate speeds. It is not due solely to rods, as opposed to cones, and does not appear to be explainable in terms of intermittent stimulation of portions of visual fields of fixed visual angle.
EEG, Measures of Complexity, and Preference for Nonrepresentational Works of Art
Authors: Nicki Richard M , Gale Anthony
Published: January 2007

With a heterogeneous sample of human subjects, alpha abundance, an inverse function of cortical arousal, was found to increase with greater complexity of a series of 18 nonrepresentational works of art. This finding is contrary to those of previous EEG studies with artificially generated stimuli, which showed increased arousal with increasing complexity; but is consistent with those which reveal an inverted-U-shaped relation between arousal and complexity when the range of complexity sample is broad. That is, at higher levels of complexity, subjects may be less able to process the information content of paintings. Ratings of interestingness and pleasingness increased with complexity; it may be that they are dependent to some extent on social learning factors.
Brightness as an Indicator to Distance: Relative Brightness per Se or Contrast with the Background?
Authors: Farnè Mario
Published: January 2007

A black and a white target are displayed, in five different conditions, on five grey backgrounds having different degrees of brightness (from very bright to very dark). The results show that the target having the higher contrast with its background is perceived as the nearer. With the off-white background, e.g., the black target appears as the nearer to the observer. This contradicts the well-known concept according to which the brighter target should in any case be perceived as the nearer (‘relative brightness’ cue). The conclusion is that the frame of reference must be taken into consideration: study of the indicators to distance in an empty space and per se is not sufficient.
Motion in Depth Induced by Brightness Changes in the Background
Authors: Farnè Mario
Published: January 2007

A disc of unvarying brightness and position is presented against a background whose brightness is continuously changing up and down. This change is perceived as a pendular movement to and from the subject and, in its turn, clearly induces an analogous but contrary movement in the disc.
The Microstructure of Dual Task Interaction. 3. Incompatibility and Attention Switching
Authors: Fisher Shirley
Published: January 2007

This report is the third in a series of reports concerned with close analysis of a dual task situation in which a five-choice serial task is combined with an auditory—verbal response task.

A situation is described in which ‘incompatibility’ is incorporated into the five-choice task in order to increase the information processing load and thus explore the effect on the mechanism believed to control the microstructure of the time-sharing process.

Results supported the notion that subjects were continuing to operate a sequential processing strategy in combining the two tasks. The structure of the interval generated by the occurrence of the auditory-verbal task was different in comparison with the compatible five-choice condition reported earlier, suggesting that the introduction of incompatibility causes a change in the characteristics of the time-sharing process. The structure of the interval remained organised and consistent, suggesting that the mechanism which controlled the time-sharing process was not disrupted by increased main task load and therefore was likely to involve a process which did not compete for attention space with task variables.

Results also revealed an effect of the digit task response on the following two serial responses. It was suggested that these were probably best described as two independent effects: one arising from the sequential processing strategy adopted, and the other arising perhaps as a function of perception of overall task difficulty.
Expanding Angles? Systematic Distortions of Space Involving Angular Figures
Authors: Heywood Simon , Chessell Karen
Published: January 2007

Using simple, single angular figures, including figures containing only one line, we have shown systematic misestimations of distance defined by these figures. These misestimations are not related to the absolute distance per se, but are related both to the size of the angle defining the distance, and to the part of the angle defining it. Some implications of these findings are discussed.
Discrimination by Young Infants of Stimuli Presented Discontinuously
Authors: Harris Paul L , Bassett Elizabeth
Published: January 2007

Four experiments are reported showing that young infants can pick up visual information from very brief displays. Pattern, edge orientation, and form can be discriminated when stimuli are presented for repeated exposures of only 300 ms.
An Optoelectronic Slide Identifier
Authors: Heard Priscilla F , Makepeace Anthony P W
Published: January 2007

An inexpensive optoelectronic slide identifier that uses binary code is described. It can be attached to most automatic projectors and provides for automatic indexing of up to two-hundred and fifty-five different coded slides, while each slide is being projected.
A Possible Explanation as to Why the Newly Sighted Commonly Perform Well on Pseudoisochromatic Colour Vision Tests
Authors: Gordon Ian E , Field David
Published: January 2007

Patients whose vision has been restored after long periods of blindness commonly experience difficulty in perceiving. Parodoxically, such patients often perform well on pseudoisochromatic colour-vision tests. A well-known example is Gregory and Wallace's subject, S B, whose performance on the Ishihara test was perfect. It is suggested that restoration of vision may be associated with relatively poor visual acuity and that this, by filtering higher spatial frequencies, enhances the legibility of pseudoisochromatic test patterns. Two experiments confirm that the Ishihara plates are more legible when seen as defocused images.
Orientation-Selective Inhibition and Binocular Rivalry
Authors: Walker Peter
Published: January 2007

It is hypothesized that a negative correlation exists between the readiness with which two visual stimuli display rivalry and the magnitude of the inhibition effects between the corresponding neural channels. With binocular rivalry being more readily observed than monocular rivalry, it is predicted that lateral inhibition between neural channels selectively sensitive to such fundamental parameters as orientation, is primarily confined to those monocularly driven channels deriving their sensory input from the same eye. In confirmation, it is shown that the visual tilt illusion, thought to reflect lateral inhibition between orientation-sensitive channels, is very much reduced under dichoptic viewing conditions. Moreover, it is shown that those subjects displaying the greatest interocular transfer of the illusion least readily experience binocular rivalry.
The Angular Function of Orientation Illusions Induced by Projected Images of Tilted Real Object Scenes
Authors: Purcell Terry , Wenderoth Peter , Moore David
Published: January 2007

Tilt aftereffects induced by line gratings are maximal when the test and inducing stimuli have an angular separation of 10°–15°. Similar effects induced by prismatically tilted real-object scenes have been found to increase monotonically with scene tilt. The difference between these two angular functions of aftereffect (that induced by gratings and that induced by real objects) has been attributed to the ‘meaning’ inherent in the real-object scenes.

The preliminary experiments described here suggest that tilt aftereffects and illusions induced by projected slides of tilted real-object scenes have angular functions similar to that induced by a line grating. Hence, the monotonically increasing angular function obtained in the prism studies is not necessarily determined by the use of real-object scenes.
Geometric Transformations of Pictured Space
Authors: Farber James , Rosinski Richard R
Published: January 2007

In general, a picture can represent a specific environment or scene only when the picture is seen from a unique viewing point. The determination of this unique point and of the distortions that occur when the picture is viewed from other points is crucial to all aspects of pictorial perception. To clarify the effects of the point of observation on pictorial space, the present paper discusses how the correct point may be calculated, provides a geometric analysis of the effects of altering the viewing point, and briefly reviews the effects of such alterations on space perception.
Assimilation Theory, Attentive Fields, and the Müller—Lyer Illusion
Authors: Bross Michael , Blair Richard , Longtin Paul
Published: January 2007

The assimilation theory of geometric illusions was employed to predict changes in the outgoing and ingoing forms of the Müller—Lyer illusions as a function of attentive field size. It was found that the theory predicted correctly the form of the function relating amount of illusion and size of attentive field only for the outgoing Müller—Lyer. For the ingoing illusion the prediction was opposite to the empirically obtained results. The findings are seen as additional evidence for the untenability of a unitary theory, such as assimilation theory, for both versions of the Müller—Lyer illusion as they fail to account for substantial differences between them.
Aftereffects of Sustained Vertical Divergence: Induced Vertical Phoria and Illusory Target Height
Authors: Ebenholtz Sheldon M
Published: January 2007

Maintaining vertical divergence of about 2 diopters for 6, 8, or 10 min was shown to yield an induced vertical phoria (IVP). IVP increased with the duration of the inducing period and decayed with time in the dark, though not completely. Decay of IVP decreased with duration of induction period and increased as a result of maintaining the normal fusional response for 30 s. Vertical eye movements in the dark, however, were ineffective in reducing IVP. Some evidence also was provided for eye-specific errors in the perception of elevation of a visible target that were appropriate to the direction of the induced phoria. It was proposed that IVP may be modulated by resetting the output of the system used to induce the original effect.
Sir Charles Bell on Visual Direction
Authors: Wade Nicholas J
Published: January 2007

Helmholtz is usually credited with demonstrating the relationship between the perception of visual direction and eye muscle activity: he said that directional judgements resulted from the effort of will involved in altering the position of the eyes. However, Bell reached the same conclusion many years earlier, primarily on the basis of experiments with afterimages: an afterimage appeared to move with voluntary movement of the eye, but it appeared stationary when the eye was moved passively.
Reaching in Very Young Infants
Authors: DiFranco Diane , Muir Darwin W , Dodwell Peter C
Published: January 2007

It has been claimed that reaching to visually presented targets is a valid indicator of perceptual capacity in very young infants. In a previous report we failed to replicate the findings on which that claim is based. Here we reanalyze some of the tapes of the first report, using a less restricted criterion for what constitutes a reach, and a much more detailed analysis of the various components of reaching behaviour. A number of components are readily distinguished and reliably observed. Infants of seven to twenty-one days show great individual variation in their reaching, from no such behaviour to a great deal. Certain clusters of the components of reaching can be used to define different reaching ‘styles’. The infants who reached most frequently in our sample all showed a dominant pattern of reaching, which in certain respects appears to be more mature than that of other babies. The finer analysis revealed no differences in the reaching behaviour to objects and pictures of objects, even among the most active reachers.
Visual Calibration of Posture in Normal and Motor Retarded Down's Syndrome Infants
Authors: Butterworth George , Cicchetti Dante
Published: January 2007

Infants with Down's syndrome are delayed in achieving motor milestones. When they first sit unsupported a discrepancy between visual and mechanical-vestibular indices of postural stability is less disruptive of their balance than in normal infants. Yet when they first stand unsupported, the same discrepancy disrupts balance more in these infants than in the normal infants. The effect of discrepant visual feedback also differs systematically as a function of the infants' experience of the posture. Monitoring posture in relation to a stable visual surround appears to be fundamental to the normal development of motor control.
Texture Discrimination and the Analysis of Proximity
Authors: Fox John , Mayhew John E W
Published: January 2007

A major theory of early visual processing has recently been proposed by Marr, which considers a number of aspects of visual perception in great detail, including grouping and texture discrimination. New phenomena associated with texture discrimination are described and experiments reported which allow a preliminary comparison of Marr's theory, as it applies to texture discrimination, with more established theories such as that due to Julesz. One experiment produced results which are clearly consistent with Marr's account, but the ability of his theory to deal with additional data on region suppression is not established. The theory of the analysis of proximity relations proposed by Fox offers a broadly satisfactory account of many texture perception results, while relying on the more fundamental parts of Marr's theory of primitive visual processes to deal with the remainder. A further attraction of proximity analysis is that it may shed new light on the classical paradox of symmetry perception. Some ways in which the preliminary proximity analysis model is incomplete are discussed, and it is concluded that development of the model may be profitable for theories of early visual processing.
Depth Inversion despite Stereopsis: The Appearance of Random-Dot Stereograms on Surfaces Seen in Reverse Perspective
Authors: Yellott John I , Kaiwi Jerry L
Published: January 2007

Inside-out relief masks of faces can be depth-inverted (i.e. seen in reverse perspective) during close-up binocular viewing. If a random-dot stereogram is projected onto such a mask, stereopsis can be achieved for the stereogram, and its depth planes are correctly seen while the mask itself, including the region covered by the stereogram, is simultaneously perceived as depth-inverted. This demonstration shows that binocular depth inversion cannot be explained by a complete loss of stereoscopic information (e.g. through monocular suppression), or by a process analogous to pseudoscopic viewing whereby retinal disparities are incorporated into perception, but with their signs uniformly reversed.
The Contribution of Colour to Three-Dimensional Ambiguities in Paintings and Drawings
Authors: Pratt Francis
Published: January 2007

This paper is about kinds of visual ambiguity that concern the author as a painter. Some effects of incompatible depth cues on the experience of looking at paintings and drawings are discussed. Particular attention is given to the role of colour as a depth cue. It is suggested that areas of identical pigmentation on different parts of a picture surface tend to be interpreted as being on the same plane. Where this interpretation is incompatible with other depth cues ‘visual tension’ results, the degree of tension being dependent on the relative strength of the cues involved. This hypothesis is illustrated and elaborated with the help of a number of line drawings.
Adaptation to Displacing Prisms in Human Infants
Authors: McDonnell Paul M , Abraham Wayne C
Published: January 2007

This research reports a first attempt to study adaptation to laterally displacing prisms in human infants of ages six to ten months. Twenty infants were tested over four days under conditions similar to those used in adult adaptation studies. Evidence was found of vigorous adaptation when infants were exposed to base-right prisms under conditions of active exposure. Detailed consideration is given to the conditions and methods of studying adaptation in infants and implications for adult studies.
Optical Defocusing Reverses Perceptual Organization
Authors: Petersik J Timothy
Published: January 2007

At a certain point during the defocusing of a reversible figure, the organization of the figure reversed unexpectedly, and the reversal seemed more abrupt than a spontaneous reversal.

The critical point is approximately constant over time for a given subject, and a similar point occurs during refocusing. This phenomenon is discussed in terms of inhibition between competing neural structures.
Monkeys Show an Oblique Effect
Authors: Bauer Joseph A , Owens Donald A , Thomas Joseph , Held Richard
Published: January 2007

Monkeys aligned a cursor bar with high-contrast square-wave gratings presented in a variety of orientations. Alignment time increased with increasing spatial frequency from 6 to 24 cycles deg−1 regardless of the orientation of the grating. At higher spatial frequencies, alignment tasks took longer for obliquely oriented gratings than for horizontal and vertical ones. Reducing grating contrast by blurring the image of the 24 cycle deg−1 grating also produced longer alignment times for the obliques. These data indicate that monkeys have an oblique effect similar to that found in humans, implying that the monkey is a useful animal model for investigating the development of meridional anisotropies.
Heritability in Visual-Geometric Illusions: A Family Study
Authors: Coren Stanley , Porac Clare
Published: January 2007

The Müller–Lyer and Ebbinghaus illusions were tested in 203 mother–father–offspring triads and 303 sibling pairs. Significant familial resemblances were found in all but the overestimated segment of the Ebbinghaus illusion. These results suggest that responses to visual-geometric illusions, mediated by optical or neural interactive mechanisms, show patterns of familial resemblance which may be based upon heritable factors.