bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstraction of Information from a Complex Display
Authors: Chen May J , Allnutt Phillip
Published: January 2007

Two experiments concerned with simultaneously abstracting information about different dimensions from the same display were carried out. In experiment 1 the subject was briefly shown a complex display containing coloured forms with three values of each dimension. Instead of identifying the individual items in the display (such as red triangle, blue square, etc), the subject was to abstract and report in any order the different dimensional values (e.g. red and blue for colour, and triangle and square for form). The results showed that the accuracy of performance was independent of the way in which two dimensions were combined, whether they were orthogonal, partially correlated, or completely correlated. The results showed that colour and form were processed independently and that the perception of one was not facilitated or interfered with by the presence of the other in the same display. In experiment 2 various numbers of values from each dimension were combined orthogonally within each display. The subject's task was the same as in the previous experiment except that the order of report of the two dimensions was specified for each subject. Suppose the dimension reported first is X, and that reported second is Y. The results showed that the number of X values not only detrimentally affected the accuracy of reporting the X values, it also reduced the accuracy of reporting Y owing to memory impairment. The number of Y values, on the other hand, affected only the report of Y values. The results were discussed in terms of a parallel-processing system which proposes no capacity limitation.
Area 18 of the Cat: The First Step in Processing Visual Movement Information
Authors: Orban Guy A
Published: January 2007

In cats, responses of area 18 neurons to different moving patterns were measured. The influence of three movement parameters—direction, angular velocity, and amplitude of movement— were tested. The results indicate that in area 18 no ideal movement detector exists, but that simple and complex cells each perform complementary operations of primary visual areas, i.e. analysis and detection of movement.
Geometry in Visual Space—Some Method-Dependent (Arti)Facts
Authors: Ehrenstein Walter H
Published: January 2007

The measure of scalar curvature K varies with the method used to determine it. Overconstancy is found only with simultaneous comparison, nearly perfect constancy results from successive judgement, while absolute judgement produces underconstancy.
Recovery from Adaptation to Moving Gratings
Authors: Keck Max J , Pentz Benjamin
Published: January 2007

Short-term adaptation to moving sinusoidal gratings results in a motion aftereffect which decays in time. The time decay of the motion aftereffect has been measured psychophysically, and it is found to depend on (i) the spontaneous recovery from the adapted state, and (ii) the contrast of the test grating. We have measured the decays for various test conditions. An extrapolation of the measurements allows us to obtain a decay which represents the time course of the spontaneous recovery of the direction-sensitive mechanisms.
A Delayed Induced-Motion Illusion
Authors: Robinson George M , Moulton Janice
Published: January 2007

We report a striking visual illusion which involves an induced motion that is delayed in time. An observer visually tracks a moving target in the neighborhood of a fixed target. The fixed target appears to be entrained by the moving target and appears to follow its movements after a lag of 0.33 second. A series of experiments showed that while the illusion depends on low background salience it obtains with both smooth and oscillatory motion in all directions including depth, under monocular and binocular viewing, in the absence of vestibular and kinesthetic motion cues or eye movements, and under a wide range of relative and absolute target luminance and position. The strength of the illusion and the magnitude of the induced movement's delay seem not to depend on any of the above factors. The illusion, by resisting a peripheral explanation, may provide some clues to central perceptual processing. In addition, we suggest the possibility that errors of judgment based on the nonveridical perception of motion displaced in time may play a role in nighttime automobile and aircraft accidents.
Hypotheses in Perception: Their Development about Unambiguous Stimuli in the Environment
Authors: Power Roderick P
Published: January 2007

A series of seven photographs which depict a real scene as it is approached by an observer were shown, in sequence, to ninety-six university students. The photographs were either projected colour transparencies or black-and-white prints. Two sizes of photographs were used in each set and the series was presented with or without the first photograph. In earlier studies in which blurred photographs were used as stimuli, observers were unsure about their hypotheses. That was not the case in this study. Although individual observers differed widely in their initial hypotheses, the initial photographs were not perceived as ambiguous. It required on average from 2.9 photographs (large, black-and-white, full series) to 4.5 photographs (small, colour, full series) for correct identification. In general, colour is a hindrance to correct identification. For the full series approximately three hypotheses are put forward before the scene is correctly identified.
Recognition and Knowledge of the Water-Level Principle
Authors: Howard Ian P
Published: January 2007

Piaget and Inhelder showed that children do not realize that the surface of a fluid remains horizontal in a tilted vessel. Several studies have since shown that many adults do not have an adequate concept of the water-level principle. However, in all these studies, drawings of vessels, or other abstract displays, were used. The present experiment is an investigation of whether adults who do not know the water-level principle are able to recognize the correct orientation of a fluid surface in realistic three-dimensional scenes and in cinematographic sequences. It was found that all subjects who could state the principle clearly, could precisely and accurately recognize the correct fluid level. More than half the subjects did not know the principle and all these subjects showed evidence in their judgments of only the crudest perceptual schema.
Comparison of Eye Movements over Faces in Photographic Positives and Negatives
Authors: Luria Saul M , Strauss Mark S
Published: January 2007

Eye movements were recorded while subjects viewed ordinary portraits and photographic negatives of those portraits. Under both conditions they first studied sixteen portraits and then tried to decide which of forty-eight portraits they had just seen. They made more errors of recognition while viewing negatives, and their fixation patterns were significantly altered: there was a decrease in the percentage of fixations directed to the eyes, nose, and mouth, and an increase for such details as the ears, cheeks, chin, cap, and necktie. There was also a decrease in the ratio of fixations to the most fixated detail compared to the least fixated detail.
Lability of Odor Pleasantness: Influence of Mere Exposure
Authors: Cain William S , Johnson Frank
Published: January 2007

Subjects judged the pleasantness of various odorants both before and after intensive exposure to a pleasant, a neutral, or an unpleasant odorant, or a short period of relaxation. Intensive exposure comprised a 30 min task of intensity discrimination. The outcome implied that exposure to an odorant can modify its own pleasantness readily, but not so readily that of other odorants. Exposure to the pleasant lemon-smelling substance citral reduced its subsequent pleasantness, whereas exposure to the unpleasant rancid-smelling substance isobutyric acid reduced its subsequent unpleasantness. The results were compatible with the notion of affective habituation. Variability of the pleasantness judgments was uniform throughout the hedonic continuum. That is, subjects agreed as much about hedonically neutral odors as about extremely pleasant and unpleasant odors.
Illusory Contours and the Ends of Lines
Authors: Kennedy John M
Published: January 2007

A series of lines pointing towards a central region induces an illusory brightness effect that is systematically related to the angle formed by the lines and the contour of the illusory brightness. As the lines veer to become tangents the illusory brightness decreases.
The Relationship between Apparent Depth and Disparity in Rivalrous-Texture Stereograms
Authors: Frisby John P , Mayhew John E W
Published: January 2007

A series of experiments is reported on rivalrous-texture stereograms composed of narrow-band-filtered random noise. Experiment 1 found that the apparent depth—disparity function for such stereograms was different from that observed with similar but nonrivalrous stimuli. In particular, rivalrous divergent disparities produced the same depth as rivalrous zero disparity and this latter disparity itself produced a significant degree of protruding (i.e. ‘convergent’) depth in a certain type of rivalrous-texture stereogram. Free inspection was permitted and disparities were in the range 16 min convergent to 16 min divergent. Experiment 2 found no convincing evidence for reliable qualitative depth discriminations from tachistoscopic presentations of rivalrous-texture stereograms, using a forced-choice task requiring a discrimination between 16 min convergent and 16 min divergent conditions. This task was solved easily for equivalent nonrivalrous stimuli. Experiment 3 measured a hitherto unreported binocular depth effect, termed ‘paradepth’, which is produced by presenting a target in one field only. This effect appears to be a genuine binocular depth effect and not just the result of an ordinary monocular masking depth cue. The size of the depth effect was found to be a function of the width of the target. The overall conclusion derived from the series of experiments is that rivalrous-texture stereograms are complex stimuli capable of yielding curious and unexpected depth effects which are not readily explained in detail within any existing theoretical framework.
The Utilization of External and Movement Cues in Simple Spatial Tasks by Blind and Sighted Children
Authors: Millar Susanna
Published: January 2007

The role of visual experience in coding spatial position by movements or by external cues was examined in simple (nonrotational) shift tasks with blind and sighted children. Age and the salience of external cues were also of interest. Results showed that the congenitally totally blind used movement cues significantly more even when external cues were present and prominent. The blind with minimal visual experience coded by external cues, but made errors beyond the age by which blindfolded sighted children performed correctly. It was argued that visual experience affects coding by drawing attention to external cues, and by providing more adequate spatial information than other sources usually available to the blind. In its absence, movement coding and self-reference can become preferred strategies.
Eye Guidance in Reading: Fixation Locations within Words
Authors: Rayner Keith
Published: January 2007

Three broad categories of models of eye movement guidance in reading are described. According to one category, eye movements in reading are not under stimulus or cognitive control; the other two categories indicate that cognitive activities or stimulus characteristics are involved in eye guidance. In this study a number of descriptive analyses of eye movements in reading were carried out. These analyses dealt with fixation locations on letters within words of various lengths, conditional probabilities that a word will be fixated given that a prior word was or was not fixated, and average saccade length as a function of the length of the word to the right of the fixated word. The results of these analyses were supportive of models which suggest that determining where to look next while reading is made on a nonrandom basis.
Hans Gertz Revisited: The Different Effects of Invisibility and Darkness on Pursuit Eye Movements
Authors: Glenny Georgina , Heywood Simon
Published: January 2007

Subjects were required to track their self-moved hands with smooth eye movements in total darkness. The effect of holding transparent and opaque screens between the eyes and the hand upon pursuit eye movements was examined. Opaque screens produced a significant decrement in pursuit when the eye was moving in a direction in which it was generally less efficient at making smooth eye movements.
Recalibration of the Convergence System
Authors: von Hofsten Claes
Published: January 2007

Adaption to convergence-altering prism spectacles was studied. The subjects were trained for 8 min with either convergence-increasing or convergence-decreasing prisms. Before and after training they estimated the distance to a binocular dot varying in the stimulus it provided to convergence. Both the preadaptation and postadaptation estimates showed that the reciprocal of estimated target distance is linearly related to convergence. Further there was a consistent change in the direction of adaptation expected from the preadaptation to the postadaptation test. This change was accounted for in terms of a recalibration of the effective absolute convergence level.
The Relational Determination of Length Illusions and Length Aftereffects
Authors: Brigell Mitchell , Uhlarik John
Published: January 2007

When two lines were presented simultaneously, in an illusion paradigm, the judged length of one of the lines (the focal line) assimilated toward the length of the contextual line. When the lines were presented sequentially, in an aftereffect paradigm, the apparent length of the focal line was displaced away from the length of a previously presented contextual line (i.e. contrast). The largest effects obtained at inverse contextual-to-focal length ratios: 1·67:1 for contextual lines longer than the focal line and 0·60:1 for contextual lines shorter than the focal line. Overestimation of focal length was larger than underestimation for both illusions and aftereffects despite the fact that identical stimuli produced effects in opposite directions in the two paradigms. Results were discussed in terms of a neural length-coding model and were related to visual size constancy.
The Münsterberg Illusion and ‘Irradiation’
Authors: Moulden Bernard , Renshaw Judy
Published: January 2007

The Münsterberg illusion is a compelling phenomenon for which there is no generally accepted explanation. It is suggested that two different contour-shifting effects operate in this illusion, and these are named the ‘symmetrical effect’ and the ‘corner effect’ respectively. It is further suggested that both of these effects are caused by ‘irradiation’, and an attempt is made to cast some light upon the phenomenon of irradiation, which is itself only poorly understood.
Identification of Familiar and Unfamiliar Faces from Internal and External Features: Some Implications for Theories of Face Recognition
Authors: Ellis Hadyn D , Shepherd John W , Davies Graham M
Published: January 2007

Three experiments are reported in which recognition of faces from whole faces or internal or external features was compared. In the first experiment, where the faces were of famous people, an advantage was found for identification from internal features. In the second experiment involving unfamiliar faces, however, no difference was found in recognition rates when subjects were given the internal or the external features. In a third experiment famous faces were presented and mixed with other famous faces for a recognition test. As in experiment 1, better recognition occurred from internal as compared with external features. It is argued that the internal representation for familiar faces may be qualitatively different from that for faces seen just once. In particular some advantage in feature saliency may accrue to the internal or ‘expressive’ features of familiar faces.

The implications of these results are considered in relation to general theories of face perception and recognition.
Genetic and Environmental Factors in Orientation Anisotropy: A Field Study in the British Isles
Authors: Ross Helen E , Woodhouse J Margaret
Published: January 2007

Visual acuity for the detection of gratings at four orientations was measured for groups of ten boys and ten girls aged five to seven years, from the following four populations: Scots in Glasgow, Pakistanis in Glasgow, Gaels in Stornoway (Outer Hebrides), and East Anglians in Littleport (Cambridgeshire fenlands). The Glaswegians, both Scottish and Pakistani, showed the normal pattern of anisotropy, with poorest acuity for oblique orientations; the East Anglians showed no significant anisotropy; while the Gaels were unusual in showing poorest horizontal acuity. A group of fourteen Pakistani children in Stornoway differed slightly from a matched group of Gaels. The group differences bore little relation to the visual environments, and were probably due to genetic or cultural factors. The relatively poor horizontal acuity of the Gaels was not correlated with astigmatism. Sex differences were also found, with the boys showing higher mean acuity and a higher ratio between vertical and oblique acuity.
Random-Dot Stereograms of Real Objects: Observations on Stereo Faces and Moulds
Authors: Georgeson Mark A
Published: January 2007

A simple technique for producing random-dot stereograms of real objects is described. It is then shown that stereograms of inside-out faces (moulds) cease to be perceptually reversible only when the presentation is truly cyclopean. Further possible applications of the technique are outlined.
Illusory Contours as the Solution to a Problem
Authors: Rock Irvin , Anson Richard
Published: January 2007

The perception of certain figures with illusory contours entails a reversal of figure and ground. It is hypothesized that this process occurs in two stages. First, some factor must suggest or cue the reversal. Experiments are described that isolate three such factors, namely, alignment of physically present contours, recognized incompletion of parts of the stimulus array, and set. Once cued, however, other experiments indicate that in a further stage of processing the solution is examined with respect to its compatibility with the stimulus display or with other perceptual properties to which the display gives rise. Only if such compatibility is present will the perception of a figure with illusory contours be maintained.
Cerebral Asymmetries in Random-Dot Stereopsis: Reversal of Direction with Changes in Dot Size
Authors: Pitblado Colin B
Published: January 2007

Visual field differences in stereoscopic form recognition using Julesz-type random dot stereograms were investigated. Dot size was varied in order to test the possibility that variations in the carrier dimension have contributed to past estimates of visual field differences. Twelve male and twelve female subjects, all right-handed, appeared for three test sessions—one with each different dot size. In each session the stimuli were flashed twenty-four times in each visual field, for 120 ms. Results showed no overall visual field effect, but a highly significant interaction between visual field and dot size. For small dots, left visual field superiority was observed, as previously reported by Durnford and Kimura. With large dots, however, the right visual field was superior. This reversal of visual field differences as a function of dot size implies that there is no consistent cerebral hemispheric specialization for stereopsis or stereoscopic form recognition per se. Instead, it appears that there is relative hemispheric specialization for responding to the carrier of stereoscopic information.
The Visual Stimulus for Saccadic Eye Movements in Human Observers
Authors: Findlay John M
Published: January 2007

Three experiments are reported in which the salience of visual stimuli is assessed by finding which of two competing peripheral stimuli elicit a saccade when both are presented simultaneously with the use of a paradigm due to Lévy-Schoen. The first experiment shows how salience is affected by position in the visual field. A strong effect of retinal eccentricity is found which is compared with the cortical magnification factor. Additionally directional biases occur. The second experiment shows that temporal change appears to be significant in eliciting a saccade rather than any specific properties related to movement. The third experiment shows that contour at high spatial frequencies does not affect salience. An area of 4 cycles deg-1 high-contrast square-wave grating possesses the same salience as an equivalent area with identical, constant, space average luminance. Taken together, the results suggest that salience might be accountable for in terms of the activation of transient channels in the visual system.
Evidence for the Role of Attentive Fields in Masking
Authors: Pressey Alexander W , Wilson Alexander E , Harper Dan W
Published: January 2007

A masking task was employed to determine whether predictions derived from the attentive-field postulate of assimilation theory could be verified. The distance between masking and test lines was varied both towards and away from the center of the attentive field. As predicted, masking was greater when the mask was near the center of attention than when it was located at the periphery of the field. A variation of the mathematical formula developed previously to predict visual illusions was employed to fit the individual and group functions found in this study.
Brunelleschi's Perspectives Reconsidered
Authors: Lynes John A
Published: January 2007

Accounts by Brunelleschi's biographers of the discovery of linear perspective are briefly reexamined. It is suggested that Brunelleschi's familiarity, as a clockmaker, with sundials may have suggested to him a method of drawing perspectives without recourse to geometrical construction from plans and elevations. This would explain several puzzling features of the first perspective, including the choice of subject (the Baptistery of San Giovanni), the lateral inversion of the painting, the necessity for a hole “as tiny as a lentil bean”, and the use of mirrors. The second perspective is then shown to embody lessons learned from the shortcomings of the first.

It is concluded that the descriptions written by Vasari and Manetti are essentially sound, but their usual interpretation is thrown into question. In particular they can no longer sustain the centuries-old claim, for which they formed the basis, that the geometrical construction of linear perspective from plans and elevations was discovered by Brunelleschi.
Irrelevance of Local Position Information in Visual Adaptation to Random Arrays of Small Geometric Elements
Authors: Foster David H , Mason Robert J
Published: January 2007

Experiments were carried out to test whether spatial relationships between local pattern features are important in the production of pattern-specific visual adaptation effects. Evidence was found for sensitivity to the shape of local pattern features, but not to their relative positions. These findings are contrasted with recent results for texture discrimination where the visual system can make use of local position information.
Effect of Peripheral Visual Field Size upon Visual Search in Children and Adults
Authors: Osaka Naoyuki
Published: January 2007

Twenty observers in each of the age groups, three, four, five, and twenty-one years, were asked to identify pictures displayed through five different sizes of peephole. Recognition latency changed as a cube-root power function of aperture area. It was found that latency decreased as age and area increased. However, the exponent of the power function showed little age-related change. Effectiveness of the peripheral visual field size was discussed in terms of magnitude of the exponent.
The Graph-Paper Effect: Subjective Stereoscopic Patterns Induced by Moving Gratings
Authors: Georgeson Mark A
Published: January 2007

Smooth tracking across an oblique grid pattern produced hallucinations of vertical and/or horizontal striations which moved with the eyes. The effect was produced by single or multiple gratings, monocularly or binocularly, but in the latter case it appeared to lie stereoscopically in the plane of fixation. Gratings containing thin lines or sawtooth edges of moderate contrast were particularly effective stimuli but sine or square waves were not. The subjective stripes had an apparent edge polarity which was opposite to that of the inducing edges or, with thin inducing lines, was determined by the lines' polarity and movement direction. Conventional explanations (eg strobe, afterimage, or moiré effects) can be ruled out. Neither the present effect nor the ‘pincushion-grid illusion’ are due to the presence of spurious Fourier components in the stimulus pattern. An extension of a previous model, involving disinhibitory interaction between movement and pattern channels, accounts for many aspects of this elaborate phenomenon. The detailed dependence of polarity on spatial waveform and movement direction implies: (i) the spatial second harmonic is a necessary component, (ii) the generating mechanism is approximately linear and has 90° phase preference, and (iii) there is a movement-induced phase lag of about 45° in the response to the second harmonic.
Visual Persistence as a Function of Spatial Frequency and Age
Authors: Lovegrove William , Heddle Margaret
Published: January 2007

Duration of visual persistence for sine-wave gratings of 1, 2, 4, 8, 12, and 16 cycles deg−1 was determined for seven-year-old, ten-year-old, and thirteen-year-old children. It was found that there was a decrease in persistence duration with age but the slope of this function for the different age groups did not change.
A Psychophysical Study of Apparent Rarefaction
Authors: Masin Sergio Cesare
Published: January 2007

Five psychophysical functions for visual density are obtained with the use of the magnitude-estimation method. Because of apparent rarefaction, a different psychophysical function ensues for each size of square used. It is found that apparent rarefaction is barely detectable for sides longer than 10–15 cm (6–9 deg). It is also found that apparent rarefaction occurs to the greatest extent when short interlinear spacings are used.
Comparing Two Objects for Size after a Comparison of One of the Objects with other Objects
Authors: File Portia E , Wilton Richard N
Published: January 2007

When shown the names of two objects, subjects determine which object is larger more slowly as the difference in the sizes of the objects decreases. This might result from variations in the time taken to access sufficient information to perform the task; information which crudely specifies size is accessed first and can be used when the sizes differ greatly; information which specifies size on a more finely graded scale must be accessed when they do not. This hypothesis was tested. Subjects shown the names of three objects, determined which object was intermediate in size. Immediately thereafter the name of another object was shown, the task then being to decide whether the object previously judged intermediate was larger than this object. In this second task reaction times increased with decreasing differences in size between the two objects; this increase was smaller, however, when the sizes of the objects in the first task were similar. The results were predicted from the assumption that when the specification of an object's size in terms of fine discrimination is accessed for comparison in the first task it remains available for use in the second task; thus the time normally required for accessing that information in the second task is reduced. Some implications of the results are discussed.
Detection of Elasticity as an Invariant Property of Objects by Young Infants
Authors: Walker Arlene S , Owsley Cynthia J , Megaw-Nyce Jane , Gibson Eleanor J , Bahrick Lorraine E
Published: January 2007

Three-month-old infants were habituated to two different motions of deformation, presented ‘live’ with an object of sponge rubber. After habituation, one-third of the subjects was presented with a third deforming motion; one-third was presented with a rigid motion of the same object; and the other third was presented with a continuation of the habituation sequence. The group presented with a rigid motion dishabituated, exhibiting a sharp increase in looking time. The other two groups showed little or no increase. These results suggest that infants perceive elasticity of substance, in contrast to rigidity, as an invariant property of an object over different deforming motions.
Discrimination of Orientation by Human Infants
Authors: Essock Edward A , Siqueland Einar R
Published: January 2007

Successive discrimination of suprathreshold gratings of different orientations by two-month-old infants was tested with the use of a type of familiarization–novelty paradigm. Infants showed clear discrimination between horizontally and vertically oriented gratings. Infants failed, however, to discriminate mirror-image obliques from each other and also failed to discriminate nonmirror-image obliques. Considered along with previous demonstrations in children and adults of a greater confusability of oblique grating pairs relative to that of the horizontal and vertical pair, these findings indicate that this differential confusability of orientation is, at least in part, manifest in humans by two months of age.
The Role of the Second Oblique in the Poggendorff Illusion
Authors: Wenderoth Peter
Published: January 2007

It has been observed previously in the classic Poggendorff illusion figure that the end of the oblique line which abuts onto the vertical parallel appears more misaligned than its free end. Various theories suggest that angular distortions are largest at the point of abutment. Two experiments are reported which, however, suggest that, compared to displays in which a single dot is aligned with an oblique line, the introduction of a second, parallel oblique segment does not increase errors more at the abutting tip than at the free end, but, rather, reduces them more at the free end. These results not only cast doubt on the relative importance of angular effects alone in the classic Poggendorff display, but also emphasise the complexity of that figure as a tool in the investigation of visual processing.
Level of Response Categorisation and Reporting Consistency for Rivalry between Lines Viewed as Real Images and as Afterimages
Authors: Swanston Michael T , Wade Nicholas J
Published: January 2007

Reports of the disappearance of paired orthogonal lines viewed under binocular rivalry may be determined by the categories used to indicate the phenomenal characteristics of the display. Measures derived from logically equivalent categorisations yield consistently different estimates of disappearance. These findings correspond with those previously obtained for afterimages and steady fixation. Adequate control of response methodology is required before conclusions may be drawn regarding the underlying mechanisms of fluctuating visibility.
A Psychophysical Investigation of the Behavioural Relevance of Neurophysiological Feature Detectors (S Cells)
Authors: Smets Gerda
Published: January 2007

The aim of the study was to establish whether monaural auditory stimulation (a nonretinal perceptual variable) affects the class 1 oblique effect (a behavioural manifestation of simple cells). The left or right monaural stimulus was a pure tone, 1000 Hz, 70 dB(A), delivered continuously throughout the experimental session. The left or right monocular stimulus was a thin red phosphorescent bar the orientation of which was manipulated. In order to determine the oblique effect differential orientation thresholds for principal meridians were compared to those for oblique orientations. The results, indicating an interaction effect of the monaural and monocular stimulation on the magnitude of the oblique effect, are a further demonstration that the oblique effect is not as simple as some theories (derived from extrapolation from neurophysiological findings) would imply.
Duration Differences: Attentional Demand or Time Error?
Authors: Gray Colin
Published: January 2007

Underwood (1975) has used judgments of duration to compare the attentional demands of learning and recall. His study is critically discussed and two further experiments are reported. In experiment 1 subjects spent 50 s learning a list of words and a further 50 s either trying to recall them or learning another list. In contrast to Underwood's subjects both groups judged the first interval to have been longer than the second. In experiment 2 three separate groups of subjects spent 50 s learning a list of items (nonsense syllables, unrelated words, or related words, as in Underwood's experiment) and then a further 50 s trying to recall them. Once again the first interval was judged to have been of greater duration. The implications of these findings for the use of duration judgments as a measure of attentional demand are discussed.
Adaptation to Optically Reduced Size
Authors: Scheuhammer Joseph , Timney Brian
Published: January 2007

Previous investigators have reported some difficulty in obtaining evidence for adaptation to optically reduced size. A study is reported in which a ballistic target-pointing task was used to examine such adaptation. In the first experiment size was reduced either by means of negative spherical lenses, or cylindrical lenses which reduced image size in only one dimension. Both lens types produced a negative aftereffect of adaptation, which increased as a function of lens strength. There was also a tendency for cylindrical lenses to give larger aftereffects. In a second experiment, in which a modified adaptation procedure was used, adaptation to cylindrical distortion was found to be significantly greater than adaptation to equivalent spherical distortion. These data are interpreted with respect to the relative amounts of distance distortion induced by viewing through the different lens types. The third experiment employed a cylindrical lens and a mental rotation procedure to determine whether adaptation in the first two experiments may have been visual or visuomotor in nature. Results indicated that adaptation was not purely visual. It is concluded that it is possible to demonstrate adaptation to size distortion by using an appropriate procedure.
The Perception of Causality in Infants
Authors: Leslie Alan M
Published: January 2007

The problem of the origins of the perception of causality in infancy has received relatively little attention in the literature despite its obvious importance. Two experiments with infants 4 1/2 and 8 months old are reported which seek to investigate sensitivity to spatiotemporal continuity in simple causal events with a differential dishabituation-of-looking technique. In the first experiment inanimate events of the familiar ‘billiard-ball launching’ type were used, while in the second animate events involving a hand/object pick-up were presented. The results suggest that both age groups of infants were sensitive to certain changes in spatiotemporal continuity in both types of event, although in the case of the inanimate stimuli the younger infants reacted less positively. It is suggested that infants in the first year of life are sensitive to certain spatiotemporal event configurations and that this sensitivity could be regarded as at least a required component of a perception of causality.
The Interpretation of Stereo-Disparity Information: The Computation of Surface Orientation and Depth
Authors: Mayhew John
Published: January 2007

Two methods for interpreting disparity information are described. Neither requires extraretinal information to scale for distance: one method uses horizontal disparities to solve for the viewing distance, the other uses the vertical disparities. Method 1 requires the assumption that the disparities derive from a locally planar surface. Then from the horizontal disparities measured at four retinal locations the viewing distance and the equation of local surface ‘patch’ can be obtained. Method 2 does not need this assumption. The vertical disparities are first used to obtain the values of the gaze and viewing distance. These are then used to interpret the horizontal disparity information. An algorithm implementing the methods has been tested and is found to be subject to a perceptual phenomenon known as the ‘induced effect’.
Metacontrast U-Shaped Functions Derive from Two Monotonic Processes
Authors: Reeves Adam
Published: January 2007

Different underlying processes account for the descending and ascending portions of the metacontrast U-shaped function obtained in the flanking-masks paradigm. One or another process is dominant on each trial. Each process is monotonic with stimulus onset asynchrony in the region in which it can be measured. The two processes may be isolated by asking the subject to report on each trial not only target visibility but also whether target and mask appear simultaneous or not. Standard U-shaped functions could be obtained only as an artifact of averaging across these different types of trials.
Visual Slant Underestimation: A General Model
Authors: Perrone John A
Published: January 2007

A general model of visual slant underestimation is presented. It is based on the idea that two specific types of perceptual error occur in the evaluation of the slant angle by the observer. The reason for these errors occurring is postulated to be that reduced viewing conditions result in the deviation of the observer's perceived straight-ahead direction from the true direction. Specifically this deviation is postulated to be in the direction of the nearest part of the surface in accord with conditions that exist in our everyday environment. In the case of a slanted rectangle correct registration of the projected length of half of the surface and the correct registration of the appropriate angle of convergence will result in perception being veridical. A mechanism is outlined which indicates how both of these factors can be in error, and an equation is developed which enables the predicted slant estimates to be calculated given the dimensions of the rectangle and its distance from the eye. Equations for the case of slanted surfaces viewed through apertures are also developed. The model is assessed in relation to past slant-perception experiments and is found to be a good predictor of the large amount of previously unexplained underestimation that occurred in these studies.
Detection of Moving Stimuli in the Binocular and Nasal Visual Fields by Infants Three and Four Months Old
Authors: Finlay David , Quinn Kay , Ivinskis Algis
Published: January 2007

A technique of monocular eye patching was used to measure the response of infants three and four months old to nasally and temporally placed stimuli at various eccentricities in the visual field. The results indicated a field of binocular overlap of approximately 60 deg in infants three months old and 80 deg in infants four months old. These figures compare with visual field widths obtained under binocular viewing conditions of at least 140 deg in infants three months old and of at least 150 deg in infants four months old.
Natural Sniffing Gives Optimum Odour Perception for Humans
Authors: Laing David G
Published: January 2007

The characteristics of human sniffing episodes during odour perception have been described in an earlier paper, where it has been suggested that the techniques used by individuals may be close to those providing optimum perception. To investigate this suggestion, threshold and intensity tests with butanol, cyclohexanone, and pentyl acetate have been carried out on twenty-one subjects. Olfactory responses obtained by using natural sniffing techniques were compared with those where the number of sniffs, interval between sniffs, and size of sniffs were varied. The results indicate that it is very difficult to improve on the efficiency of sniffing techniques of individuals and that a single natural sniff provides as much information about the presence and intensity of an odour as do seven or more sniffs. A single natural sniff and the first sniff of a a natural sniffing episode were shown to have similar characteristics and most significantly both were unaffected by changes in the concentration and type of odour. Overall, the results indicate that humans achieve optimum odour perception during threshold and intensity measures with their natural multiple-sniff technique or with a single sniff. For the ‘average’ human this occurs with a sniff of inhalation rate 30 1 min−1, volume 200 cm3, and duration 0.4 s. The use of several sniffs in a sniffing episode appears to be a confirmatory action rather than a necessary one, except for the perception of odour mixtures where several sniffs are likely to be needed to aid discrimination of the components. Data from the present and earlier study provide the information necessary for the development of a standard olfactometer and standard procedures for measuring the olfactory responses of humans.
Ehrenstein Variations
Authors: Fraser Alex Stewart
Published: January 2007

Radial lines pointing towards a central circular region induce an illusory positive brightness contrast. Shift in line orientation from radial to tangential can result in negative brightness contrast and line enhancement.
The Voice-Recognition Accuracy of Blind Listeners
Authors: Bull Ray , Rathborn Harriet , Clifford Brian R
Published: January 2007

A research programme has been carried out that concerns the accuracy with which listeners can identify a speaker heard once before. The present study examined the voice-recognition abilities of blind listeners, and it was found that they could more accurately select target voices from the test arrays than could sighted people. However, the degree of blindness, the age at onset of blindness, and the number of years of blindness all failed to relate to voice-recognition accuracy.
R L Gregory and Others: The Wrong Picture of the Picture Theory of Perception
Authors: Katz Stuart
Published: January 2007

It is the position of R L Gregory and other cognitive theorists that perceptual knowledge conceived as an inner picture leads to an infinite regress, but that perceptual knowledge conceived as an abstract or coded representation does not. It is argued here that this view is mistaken.

All inner representations, whether pictorial or abstract, lead to the regress because all representations, inner or outer, require interpretation, and hence an interpreter. The problem will not disappear, furthermore, by formalizing the representation because rule-following is not equivalent to interpretation. The regress can only be avoided if the whole organism is made the interpreter, and representations are given their appropriate place: in the external world, not inside heads.
The Perception of Depth Contours with Yellow Goggles
Authors: Kinney Jo Ann S , Luria Saul M , Schlichting Christine L , Neri David F
Published: January 2007

The ability of subjects to discriminate the depth of depressions in the snow was conducted at a cross-country ski area. The percentage of correct judgments on an overcast day was significantly greater with yellow goggles than with luminance-matched neutral goggles. This experiment, suggested by the chromatic—achromatic theory of color vision, indicates why yellow goggles are popular despite many previous unsuccessful attempts to prove their effectiveness.
Optic-Flow and Cognitive Factors in Time-to-Collision Estimates
Authors: McLeod Ronald W , Ross Helen E
Published: January 2007

Time-to-collision ( Tc) estimates were obtained from twenty-four subjects who viewed film clips for varying lengths of time. The film clips showed the view from a moving car travelling towards a stationary target car, but ended 100 m before reaching the target. Viewing time varied from 2 to 6 s, approach velocity from 40 to 100 km h−1, and Tc from 3.6 to 9.0 s. It was hypothesised that, if time were needed to calculate Tc, the accuracy of Tc estimates would increase with viewing time up to some maximum. However, the results showed no effect of viewing time, and this was taken to indicate that estimates were based upon information directly available from the changing optic array at the eye of the observer. A significant velocity effect was found, accuracy increasing with velocity. Since velocity was inversely correlated with Tc, this probably implies that accuracy decreases with increasing Tc. Sex differences were found, with males giving higher and more accurate estimates than females. The relevance of these findings to the nature of Tc information is discussed.
Position in the Visual Field and Spatial Expansion
Authors: Hotopf W H Norman , Hibberd Malcolm C , Brown Susannah A
Published: January 2007

Measurements of the tilt illusion by parallelism matches have taken as their baseline data estimates of parallelism between two lines. This is because Carpenter and Blakemore and others found in this situation that parallel lines appeared to diverge at their upper ends. It was hypothesised that this effect was due to inappropriate constancy scaling—the parallel lines being interpreted as being located in a receding plane—and that consequently it was inappropriate to take this effect into account in assessing the degree of the tilt illusion. To test the theory, a horizontal line was compared with other horizontal and vertical lines lower down in the visual field. A tendency to underestimate the length of lines lower down in the visual field was found but this varied inversely with distance from the standard. The findings were accounted for on the assumption that the occurrence of inappropriate constancy scaling depended upon prior organization by contiguity which determined whether the two lines were taken as a group or not.
Evidence Relating Subjective Contours and Interpretations Involving Interposition
Authors: Stevens Kent A
Published: January 2007

Subjective contours, according to one theory, outline surfaces that are apparently interposed between the viewer and background (because of the disruption of background figures, sudden termination of lines, and other interposition ‘cues’) but are not explicitly outlined by intensity discontinuities. This theory predicts that if the cues are not interpreted as evidence of interposition, no intervening surface need be postulated, hence no subjective contours would be seen. This prediction, however, is difficult to test because observers normally interpret the cues as interposition evidence and normally see the subjective contours. Tests are reported on a patient with visual agnosia who is unable to make the usual interposition interpretations and unable to see subjective contours, but has normal ability to interpret standard visual illusions, stereograms, and in particular, stereogram versions of the standard subjective contour figures, which elicit to him strong subjective edges in depth (corresponding to the subjective contours viewed in the monocular versions of the figures).
Perception of Moving, Sounding Objects by Four-Month-Old Infants
Authors: Spelke Elizabeth S , Born Wendy Smith , Chu Flora
Published: January 2007

Infants and adults were presented with two moving objects accompanied by a single percussive sound. In different experiments, the sound occurred when one object moved through a particular spatial position, when it abruptly changed its direction of movement, or when it made contact with a rigid surface. Infants responded to the sound—object relationship whenever the sound occurred as the object changed direction, irrespective of its impacts with the surface. Adults, in contrast, responded to the sound—object relationship most clearly when sounds were synchronized with impacts. In infancy, perception of auditory—visual relationships thus depends in part on detection of discontinuities in the movement of a visible object.