Short-term auditory memory, oral perception, and experimental sound learning.
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Auditory Perception↗
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Lipreading performance as related to measurements of vision.
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Accommodation, Ocular↗
Research on adaptation to rearranged vision: 1966-1974.
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Accommodation, Ocular↗
Pictorial perspective: perception of size, linear, and texture perspective in children and adults.
Perception of size, linear, and texture perspective was investigated in third-grade and sixth-grade children and in college adults in three separate studies. A matching task required the observer to choose from a set of four alternative real scenes the correct match for the test stimulus, which was either a picture or a real scene. Correct performance required that the subject utilize perspective information for both size and distance distance relations. Erroneous choices available to the subject indicated errors in size judgement, in distance judgment, or in both simultaneously. View was either restricted at the correct station point or was free, with head motion. There were no significant effects of grade level. For all three groups, mean percent correct was nearly 100% with the real-scene test stimuli, and significantly below the chance level with the picture test stimuli. Errors in size judgment occurred most frequently, indicating that the geometrically correct rate of perspective convergence was too rapid to be seen by the subjects as perceptually acceptable. With size-perspective information alone, the number of size plus distance errors also increased significantly. There was no significant effect of viewing condition.
Adult↗
Pictorial depth and related constancy effects as a function of recognition.
It is argued that while pictorial cues must be fundamental in the perception of an extended ground plane in daily life (and, by definition, in the perception of depth in pictures), the traditional pictorial cues such as perspective or texture gradients are neither a necessary nor a sufficient basis for it. That they are not necessary was shown by experiments in which such cues were eliminated from pictures representing a scene in depth. Illusory size perception based on localization of objects in depth in such pictures nonetheless occurred. That they are not sufficient was shown by experiments in which photographs of grassy fields did not yield impressions of depth or related size illusions when conditions were such that the scene was not recognized. Once recognized, however, these same pictures did yield such perceptions. It is suggested that a critical step in perceiving depth based on pictorial information is recognition of the scene.
Art↗
Development of sensitivity to information provided by cast shadows in pictures.
The shadow cast by an object in a two-dimensional picture can specify for the observer the spatial relations between that object and its surroundings, and also the shape and size of the object itself. Some sensitivity to this information is present even in three-year-old children. Experiment 1 provided evidence that three- and four-year-old children can rely on the shape of the shadow cast by an object to judge the shape of the object. In experiment 2, with adults and three- and four-year-old children, the location of the shadow cast by an object influenced the perceived depth and height off the ground plane of the object. Although even the three-year-old children were sensitive to the location of the cast shadows, there was evidence of improvement with age in judging the distance and size of the object. The three-year-olds were not able to judge the object's size when the location of the cast shadow provided the only differential information for size. In contrast, they were significantly better in judging size when the location of the object, rather than the location of the shadow, was varied.
Adult↗
A distinctive characteristic of pictorial perception: the zoom effect.
To investigate the role of flat surface information for the plane of projection in pictorial perception, three studies were designed in which varying amounts of such information were made available to adult subjects. The first study tested preferences for true or modified linear perspective under conditions of presence or absence of surface texture cues for the plane of projection. In the second and third studies, the absence of texture cues for the plane was coupled with the addition of motion parallax and binocular information respectively. It was found that adults showed a consistent preference for parallel perspective in pictures when the flat-surface information was provided either by visible texture or by motion parallax; but no consistent preference for either true or modified perspective in the absence of all three sources of flatness information or when the flat surface information was given only by binocular cues in the absence of visible surface texture of visible surface texture or head motion.
Cues↗
Two dimensionality of the correspondence process in apparent motion.
A fundamental process underlying motion perception is the matching of corresponding elements in different views. In this correspondence process spatial separation between elements plays a major role. The relevant separation is shown by the current study to be the two-dimensional, uninterpreted distance, a finding that has an implication to the level at which the correspondence process is carried out. The current findings are compared with earlier results concerning 'optimality' of apparent motion to conclude that optimality cannot serve as a measure for the correspondence strength.
Depth Perception↗
The relationship between brightness contrast and illusory contours.
One group of subjects rated differences in brightness and another the clarity of illusory contours for eight figure-ground combinations of the Kanizsa and Ehrenstein patterns made from Munsell papers. For four combinations there was a difference in Munsell value (brightness) between figure and ground and for another four no difference. For the latter the pattern was derived from differences in hue or colour quality. For the combinations with a Munsell value difference the ratings of both brightness difference and contour clarity were high and for those of uniform value both were low. The results are interpreted as supporting the argument that illusory contours derive primarily from contrast-induced differences in brightness and possibly in colour between contiguous, physically uniform regions.
Color Perception↗
Scanning visual images: implications for the representation of space.
This study investigated whether reaction time to detect an item within an image increases as a monotonic function of the relative or the absolute distance from the starting item to the probed item with the image. It was found that when relative probed distances were manipulated and absolute distances kept constant and, conversely, when absolute distances were manipulated and relative distances kept constant, reaction times were invariant across relative distance but increased as a function of increasing absolute distance. This result may be interpreted either in terms of operations within an imaginal representation or in terms of operations on propositional statements underlying the image.
Adult↗
A versatile colour stimulus generator.
An inexpensive colour-picture generating system is described and a few applications are indicated. The basic comprises a microprocessor; a colour television monitor with R, G, and B inputs; and a number of video memories. The most important characteristic of the apparatus is the way in which video memories are used in combination with a set of colour registers and very fast digital/analog converters. The equipment permits display of any kind of figure with a maximum of eight colours simultaneously present. Figures may be generated point by point by the experimenter, or by computer. Colours can be changed continuously with the R, G, and B channels each receiving one out of 256 possible values.
Color↗
Learning to see the impossible.
Four experiments investigating children's ability to detect the impossibility of impossible figures are reported. In the first, children were required to identify the impossible figure from a pair of corresponding possible and impossible figures. Whilst seven-year-old children were able to detect the impossibility of certain impossible figures, their overall level of performance was lower than that of older children. Regardless of age, the impossibility of some types of figure was found to be relatively easy or difficult to detect. Experiment 2 confirmed this pattern of results using a task that required children to copy possible and impossible figures from memory. Experiment 3 showed that, when the impossibility of an impossible figure is not readily detected, this is not due to failure to understand the conventions used in that figure to represent depth and solidity. In experiment 4 predictions from different hypotheses concerning the principal factor responsible for the detection of impossibility were tested. Results support the view that the detection of impossibility requires the construction of a mental representation (internal model) of the inter-relations of the constituent parts of the depicted object. It is suggested that the construction of such internal models may be of general importance in picture perception.
Adolescent↗
Are the obtuse angles the key components of the Poggendorff illusion?
An experiment is reported which confirms and extends a previous finding that amputations of the Poggendorff figure do not necessarily result in large positive effects with obtuse-angle stimuli, and small or even negative effects with acute-angle stimuli. Indeed, the acute-angle effects found were significantly greater than the obtuse-angle effects, and the full Poggendorff error was not explicable in terms of the linear summation of the component-angle effects. An 'alignment displacement effect' reported earlier by Hotopf and Obonai was shown to occur, but could not be an important component of the Poggendorff illusion.
Adolescent↗
Perceptual learning of illusory contours and colour.
An adequate account of the phenomena of illusory contours (ICs) will require an understanding of the genesis of such effects. There are two main techniques used to study perceptual genesis: the first is to slow down the relevant perceptual processes and to study them during perceptual learning; the second employs tachistoscopic exposures and backward masking. To date the technique of perceptual learning has not been shown to be applicable in the case of ICs. Two experiments are reported in which perceptual learning is used to study ICs. It is demonstrated that subjects can learn to see, first, illusory contours and, second, illusory colour. The suggestion is made that although there may be different kinds of illusory phenomena which may arise in different ways, these may all depend upon a common set of mechanisms.
Color Perception↗
The effect of two-dimensional and three-dimensional distance on apparent motion.
The problem of how the visual system matches corresponding inputs from one instant to the next to produce the perception of motion has been experimentally examined. The specific concern was whether this correspondence problem is solved prior to the interpretation of three-dimensional distance. Observers judged the degree of apparent motion between pairs of lights in a conflicting motion display. Spatial separation of the lights was varied in two and three dimensions in order to assess whether retinal distance, actual depth, or some combination of these provided critical information for correspondence. The results support Ullman's contention that only two-dimensional (retinal) distances are used in establishing correspondence in motion perception.
Depth Perception↗
Optic-flow and cognitive factors in time-to-collision estimates.
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 9.0s. 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.
Adolescent↗
Motion parallax information for direction of rotation in depth: order and direction components.
The work of Hershberger and his associates has demonstrated the effectiveness for judging direction of rotation in depth of several components of motion parallax. Confounding and conflicting results have made the status of two of these transformations, labeled Direction and Order, unclear. A study is reported in which the problems encountered in previous studies have been eliminated. College students correctly judged the direction of rotation of horizontal rows of dots which appeared to rotate in depth, which demonstrates that Direction and Order can, in fact, provide useful information about direction of motion in depth.
Adult↗
Apparent relative size in the judgment of apparent distance.
In experiment 1 judgments of the apparent distance of comparison figures (squares or triangles) were obtained under reduction conditions. These comparison figures were either shaped the same as or different from equidistant standard figures, and were half, equal to, or double the area of the standard figures. Apparent distance was found to be a linear function of the relative area of the comparison figure both in same-shape and different-shape stimulus pair conditions. In addition, apparent distance was found to be a function of perceived area, because in different-shape conditions triangles were generally seen to be closer than squares even when the real area of the standard and comparison was equal. The results of experiment 2 and 3 provide some evidence that the effect of different shapes of standard and comparison on apparent distance is due to the observers' perception of the height rather than the area of figures. The series of experiments shows that the traditional transactionalists' explanation of relative size as a cue for distance is inadequate.
Adult↗