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Biomedical subjects

J G Bremner

Publications and source records attributed to J G Bremner.

14 recordsLinked to original sources
PubMed2001

Use of cue configuration geometry for spatial orientation in human infants (Homo sapiens).

Research with both rats and human infants has found that after inertial disorientation, the geometry of an enclosed environment is used in preference over distinctive featural information during goal localization. Infants (Homo sapiens, 18-24 months) were presented with a toy search task involving inertial disorientation in 1 of 2 conditions. In the identical condition, 4 identical hiding boxes in a rectangular formation were set within a circular enclosure. In the distinctive condition, 4 distinctive hiding boxes were used. Infants searched the goal box and its rotational equivalent significantly more than would be expected by chance in the identical condition, showing that they were sensitive to the geometric configuration of the array of boxes. Unlike the results of studies using a rectangular enclosure, however, in the distinctive condition, infants searched at the correct location significantly more than at other locations.

Cues↗
PubMed2000

The role of good form in young Infants' perception of partly occluded objects.

Young infants have been reported to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion, but not on the basis of stationary information (e.g., P. J. Kellman & E. S. Spelke, 1983). We investigated the possibility that 4-month-old infants will attend to and utilize the global configuration (i.e., the "good form") of a partly occluded, moving object to perceive its unity and coherence behind the occluder. In the first experiment, infants viewed a partly occluded circle or cross that translated laterally. Infants who habituated in the minimum number of trials ("fast habituators") showed a reliable posthabituation preference for a broken object over a complete object, indicating perception of unity in the habituation display. Slow habituators exhibited no posthabituation preference. In the second experiment, infants were presented with small ring and cross displays, and the infants looked longer at the broken object. There were no reliable differences in performance between fast and slow habituators. A control group demonstrated no reliable posthabituation preference. In three additional conditions, infants viewed either a partly occluded half ring or a display in which two rod parts were either relatable and nonaligned or nonrelatable. The results indicated that curvature per se provided information in support of completion, in addition to global configuration and motion. Implications for theories of infants' visual development are discussed.

Case-Control Studies↗
PubMed1997

A change in viewpoint promotes use of height-in-picture as a depth cue in 5- to 7-year-olds' drawings of a simple depth relationship.

Height-in-picture emerges between 6 and 7 years of age in children's drawings as the first indication of portrayal of depth relationships, but can be promoted earlier by the use of a number of experimental manipulations. The present studies investigate whether changing, and hence drawing attention to, the child's viewpoint promotes use of height-in-picture. In the first study, 5/6- and 6/7-year-old children were asked to draw two blocks, arranged in depth. Following this, the child-array relationship was altered, either by moving the child through 90 degrees or by rotating the array through 90 degrees. Children then drew again what was now a left-right arrangement, whereupon the transformation was reversed and they made a final drawing. Only when children moved to a new standpoint was there a significant increase in vertical portrayal between first and third drawings. It was not simply the movement of the child that prompted use of height-in-picture because there was no such effect in conditions in which the child was moved but made an unrelated drawing from the new position. These results indicate that making viewpoint salient by asking for a drawing from a new position prompts young children to portray a simple depth relationship.

Age Factors↗
PubMed1994

Processes underlying young children's spatial orientation during movement.

Children between 1.5 and 4 years old were tested for their ability to relocate a hidden object after a 180 degrees self-produced movement around an array of four locations. In one task the object's location relative to the other locations could be uniquely defined within one dimension, while in another two dimensions were needed to do this. No differences emerged between conditions, and by 3 years few errors occurred, despite the fact that children were unable to view the array during movement. This indicates either that young children encounter no specific difficulty in coordinating dimensions or that they solved the task without recourse to such a system. An error analysis supports the second possibility. Children apparently tackled the task by a system directly related to body movement, since errors were frequently the result of incomplete compensation for movement around the array. In a second study in which the four containers were placed in contact, children's performance declined and the relation between direction of movement and error was replaced by some evidence for updating on the near-far dimension accompanied by failure to update the left-right dimension. Thus children appear to change strategy when the problem requires more precise specification of target location.

Child, Preschool↗
PubMed1991

Sensitivity to viewpoint in children's drawings of objects and relations between objects.

Previous literature suggests that young children are relatively insensitive to viewpoint, only showing their view when the task is manipulated to provoke it. In contrast, older children appear to become more sensitive to viewpoint and it has been claimed that there is a developmental progression toward use of linear perspective as a means of drawing a view-specific scene. This study investigates sensitivity to viewpoint by manipulating it directly. Children between the ages of 6 and 14 years were asked to draw an L-shaped array of three cubes from one of three views: frontal eye level, frontal looking down, and corner looking down. At every age children showed sensitivity to their view in the sense that there were consistent differences between the drawings produced in the three viewing conditions. In the case of younger children this did not lead to an accurate portrayal of either their view or the array relations. Older children portrayed their view and the array relations more accurately, and viewpoint had a strong effect on the choice of projection system both within and between objects. There was no evidence of a general progression toward use of linear perspective.

Adolescent↗
PubMed1991

Form perception at birth: Cohen and Younger (1984) revisited.

Cohen (1988; Cohen & Younger, 1984) has suggested that there is a shift in the perception of form sometime after 6 weeks of age. Prior to this age infants can remember the specific orientations of line segments, but cannot process and remember the angular relations that line segments can make. Experiment 1 used simple line stimuli with newborn infants to test this suggestion. Following habituation to a simple two-line angle the newborns dishabituated to a change of orientation but not to a change in angle, confirming Cohen and Younger's suggestion that orientation is a powerful cue in early shape perception. In Experiments 2 and 3 newborns were familiarized either to an acute or to an obtuse angle that changed its orientation over trials. On subsequent test trials the babies gave strong novelty preferences to a different angle. Alternative interpretations of the results are discussed, but these experimental findings are compatible with the suggestion that newborns can quickly learn to process angular relations, and that rudimentary form perception may not be dependent on a lengthy period of learning and/or maturation for its development.

Attention↗
PubMed1989

Perceptual and intellectual development in infancy.

The conventional view of development in human infancy is that objective awareness of the surrounding world is gradually constructed during the first 2 years through the infant's actions on the environment. However, recent work on the perceptual abilities of young infants indicates that even newborns perceive objective properties of their surroundings, detecting depth and displaying perceptual constancies that have hitherto been attributed only to older infants. In consequence it is necessary to revise our model of infant development. Since evidence points to objective perception from birth there is no need to postulate developmental processes that lead to its construction during development. However, as infants gain new capabilities for acting on the world, they have to develop knowledge of how these actions relate to the perceived world. It is suggested that this sort of knowledge is constructed through active experience.

Child Development↗
PubMed1984

Errors towards the perpendicular in children's copies of angular figures: a test of the bisection interpretation.

Children distort angular figures so that the constituent angles are nearer 90 degrees than they should be. This could be due to a perpendicular bias or a bisection bias, or to both. A study is reported which was designed to establish whether a perpendicular bias would appear independently of bisection. Twenty four-year-old children were tested on two types of angular figure: (i) a baseline with another line joining at the end at 45 degrees, 90 degrees, or 135 degrees and (ii) a baseline with another line joining at the middle at 45 degrees or 90 degrees. Perpendicular errors were obtained both for 'end' and for 'middle' figures, but overall more strongly for 'middle' figures. However, while 90 degrees 'middle' figures were copied more accurately than 45 degrees/135 degrees figures, this effect was only obtained for vertical and horizontal presentations of 'end' figures, and was reversed for oblique presentations. Also, for 'end' figures, directional errors varied with subtended-line orientation, whereas for 'middle' figures they varied with baseline orientation. It is concluded that although errors towards the perpendicular do occur with single-angle figures, angle equalisation may take place when there are two adjacent angles in the figure. One interpretation of the differing orientation effects is that in 'middle' figures strong internal relational forces produce a distortion that varies with the angle at which the figure is viewed, whereas in 'end' figures the absence of relational forces within the figure leads to a stronger influence from external cues.

Child, Preschool↗
PubMed1984

Piagetian stage IV search errors with an object that is directly accessible both visually and manually.

Previous work has shown that infants make the Piagetian stage IV error when the object is covered by a transparent occluder. However, it is not clear whether this happens because nine-month-old infants' failure to understand the identity of hidden objects extends to visible objects, or whether they are puzzled by object relationships involving transparency. Nine-month-old infants were presented with one of three different stage IV tasks in which the object was visible and uncovered at the second location. Stage IV errors were obtained with the object visible, but only when a covered place was provided at the first location. It is concluded that this result is stronger evidence that the stage IV error is not simply a hidden-object phenomenon, and that it may be best explained by taking account of infants' functional place knowledge, as well as their knowledge of object identity.

Concept Formation↗
PubMed1982

Children's errors in copying angles: perpendicular error or bisection error?

Following Piaget and Inhelder's work, considerable evidence has accrued showing that young children have difficulty constructing the horizontal and vertical in particular drawing tasks. However, one recent study by Ibbotson and Bryant interpreted these difficulties as lying with angle reproduction rather than representation of horizontal and vertical. Their conclusion was that children of 3 to 5 years distort acute angles to look more like right angles. A study is reported which tests the hypothesis that this is a particular case of a general tendency to bisect angles. The results support this hypothesis. 5-year-old children reproduced bisected figures accurately, but distorted nonbisected figures towards bisection, despite the fact that they contained a right angle. The simplest interpretation is that children's representations of the figures are distorted: either locally, by angle bisection, or by increasing symmetry of the figure as a whole. One puzzling result emerged. The bisection effect only appeared with oblique-baseline figures. The tentative interpretation is that, when the baseline is horizontal or vertical, children can easily note that nonbisected figures are asymmetrical about vertical or horizontal axes, and hence resist the tendency to distort representations towards symmetry.

Art↗
PubMed1978

Spatial errors made by infants: inadequate spatial cues or evidence of egocentrism?

Nine month old infants search correctly for an object which they have seen hidden in one position, but cease to do so after they have been moved to the opposite side of the display, searching instead at a position which is apparently defined egocentrically from their experience before movement. This error can be explained on the one hand in terms of response dependence or egocentrism, or on the other hand as due to a lack of adequate spatial cues to allocentric position. In order to distinguish between these hypotheses, 64 nine month old infants were presented with a hidden object problem in which the two alternative positions had covers of different colours. The results show that infants could search correctly for an object in one location although they saw the problem from different sides. This result combines with those of other conditions to indicate that cover colour provides an adequate spatial cue, allowing the infant to specify position allocentrically, provided the correct cover maintains a stable position.

Child Development↗
PubMedDate not supplied

Relations between drawing cubes and copying line diagrams of cubes in 7- to 10-year-old children.

Previous research has suggested both links and differences between children's copying of line diagrams and their drawings of solid objects. If the diagram represents a familiar object, children make more errors than when copying a diagram of a nonobject or unfamiliar object, as if they are drawing from their representation of the object rather than copying the surface features of the diagram. However, copying a diagram yields fewer and different types of errors than drawing the equivalent solid, which suggests a different process. In Experiment 1 (n = 72), possible relations between copying and drawing are investigated by asking children to draw a solid cube, then to copy or trace a line diagram of the cube in oblique projection, and finally to draw the solid again. Copying was better than drawing, and there was positive transfer to a subsequent drawing. Tracing was very accurate, but transfer to drawing did not occur, possibly because of the automatic nature of tracing. In Experiment 2 (n = 120) different groups received versions of the copying task that differed in the extent to which temporal order of line copying was structured. Asking children to copy the lines in a systematic order led to improved copies, but this performance did not carry over to a subsequent drawing of the solid. In contrast, when temporal ordering of line copying was not manipulated, there was positive transfer from copying to the subsequent drawing. In Experiment 3 (n = 80), provision of structure that emphasized faces by color-groupings of lines or coloring faces led to improved copies and did not hinder transfer to drawing the solid. Experiment 4 (n = 90) showed that in a solid drawing task emphasis on faces but not edges produced a positive effect, both on the immediate drawing and on a subsequent drawing of a plain cube. We conclude that emphasis on order of line copying improves performance in a copying task because in that case line-to-line matching is an important element of the skill, whereas this does not aid drawing of the solid object, in which the focus is primarily on representation of faces and their interrelations.

Child↗
PubMedDate not supplied

The development of relational landmark use in six- to twelve-month-old infants in a spatial orientation task.

The ability to use the relations between visible landmarks to locate nonvisible goals (allocentric spatial coding) underlies success on a variety of everyday spatial orientation problems. Little is known about the development of true relational coding in infancy. Ninety-six 6-, 8.5- and 12-month-old infants were observed in a peekaboo paradigm in which they had to turn to a target location after displacement to a novel position and direction of facing. In a landmark condition, the target position was located between two landmarks, contrasted with a control condition in which no distinctive landmarks were provided. Six-month-old infants performed poorly in both conditions, 8.5-month-olds were significantly better with the landmarks, and 12-month-olds solved the task with or without landmarks. A follow-up study confirmed that the 8.5-month-olds used both landmarks to solve the task. This demonstration of allocentric spatial coding in 8.5-month-old infants shows earlier competence than that found in previous work in which only infants at the end of the first year were able to use landmarks relationally.

Age Factors↗