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Biomedical subjects

R Baillargeon

Publications and source records attributed to R Baillargeon.

At least 19 recordsLinked to original sources
PubMed2001

Reasoning about containment events in very young infants.

The present research examined very young infants' expectations about containment events. In Experiment 1, 3.5-month-old infants saw a test event in which an object was lowered inside a container with either a wide opening (open-container condition) or no opening (closed-container condition) in its top surface. The infants looked reliably longer at the closed- than at the open-container test event. These and baseline data suggested that the infants recognized that the object could be lowered inside the container with the open but not the closed top. In Experiment 2, 3.5-month-old infants saw a test event in which an object was lowered either behind (behind-container condition) or inside (inside-container condition) a container; next, the container was moved forward and to the side, revealing the object behind it. The infants looked reliably longer at the inside- than at the behind-container test event. These and baseline results suggested that the infants in the inside-container condition realized that the object could not pass through the back wall of the container and hence should have moved with it to its new location. Experiments 3 and 4 extended the results of Experiments 1 and 2 to 2.5-month-old infants. Together, the present results indicate that even very young infants possess expectations about containment events. The possible origins and development of these expectations are discussed in the context of Baillargeon's model (Advances in infancy research 9 (1995) 305. Norwood, NJ: Ablex) of infants' acquisition of physical knowledge, and of Spelke's proposal (Cognition 50 (1994) 431) that, from birth, infants interpret physical events in accord with a solidity principle.

Awareness↗
PubMed2001

Infants' knowledge about occlusion and containment events: a surprising discrepancy.

The present research examined whether infants acquire general principles or more specific rules when learning about physical events. Experiments 1 and 2 investigated 4.5-month-old infants' ability to judge how much of a tall object should be hidden when lowered behind an occluder versus inside a container. The results indicated that at this age infants are able to reason about height in occlusion but not containment events. Experiment 3 showed that this latter ability does not emerge until about 7.5 months of age. The marked discrepancy in infants' reasoning about height in occlusion and containment events suggests that infants sort events into distinct categories, and acquire separate rules for each category.

Age Factors↗
PubMed1999

2.5-month-old infants' reasoning about when objects should and should not be occluded.

The present research examined 2.5-month-old infants' reasoning about occlusion events. Three experiments investigated infants' ability to predict whether an object should remain continuously hidden or become temporarily visible when passing behind an occluder with an opening in its midsection. In Experiment 1, the infants were habituated to a short toy mouse that moved back and forth behind a screen. Next, the infants saw two test events that were identical to the habituation event except that a portion of the screen's midsection was removed to create a large window. In one event (high-window event), the window extended from the screen's upper edge; the mouse was shorter than the bottom of the window and thus did not become visible when passing behind the screen. In the other event (low-window event), the window extended from the screen's lower edge; although the mouse was shorter than the top of the window and hence should have become fully visible when passing behind the screen, it never appeared in the window. The infants tended to look equally at the high- and low-window events, suggesting that they were not surprised when the mouse failed to appear in the low window. However, positive results were obtained in Experiment 2 when the low-window event was modified: a portion of the screen above the window was removed so that the left and right sections of the screen were no longer connected (two-screens event). The infants looked reliably longer at the two-screens than at the high-window event. Together, the results of Experiments 1 and 2 suggested that, at 2.5 months of age, infants possess only very limited expectations about when objects should and should not be occluded. Specifically, infants expect objects (1) to become visible when passing between occluders and (2) to remain hidden when passing behind occluders, irrespective of whether these have openings extending from their upper or lower edges. Experiment 3 provided support for this interpretation. The implications of these findings for models of the origins and development of infants' knowledge about occlusion events are discussed.

Analysis of Variance↗
PubMed1998

The development of calibration-based reasoning about collision events in young infants.

Previous research indicates that, when shown a collision between a moving and a stationary object, 11-month-old infants believe that the size of the moving object affects how far the stationary object is displaced. The present experiments examined whether 6.5- and 5.5-month-old infants hold the same belief. The infants sat in front of a horizontal track; to the left of the track was an inclined ramp. A wheeled toy bug rested on the track at the bottom of the ramp. The infants were habituated to an event in which a medium-size cylinder rolled down the ramp and hit the bug, propelling it to the middle of the track. Next, the infants saw two test events in which novel cylinders propelled the bug to the end of the track. The two novel cylinders were identical to the habituation cylinder in material but not in size: one was larger (large-cylinder event) and one was smaller (small-cylinder event) than the habituation cylinder. The 6.5-month-old infants, and the 5.5-month-old female infants, looked reliably longer at the small- than at the large-cylinder event. These and control results indicated that the infants (a) believed that the size of the cylinder affected the length of the bug's trajectory and (b) used the habituation event to calibrate their predictions about the test events. Unlike the other infants, the 5.5-month-old male infants tended to look equally at the small- and large-cylinder events. Further results indicated that this negative finding was not due to the infants' (a) failure to remember how far the bug rolled in the habituation event or (b) inability to use the habituation event to calibrate predictions about novel test events. Together, the present results suggest the following conclusions. First, when shown a collision between a moving and a stationary object, infants aged 5.5-6.5 months (a) believe that there is a proportional relation between the size of the moving object and the distance traveled by the stationary object and (b) can engage in calibration-based reasoning about this size/distance relation. Second, female infants precede males by a few weeks in this development, for reasons that may be related to sex differences in the maturation of depth perception.

Age Factors↗
PubMed1998

Object individuation in infancy: the use of featural information in reasoning about occlusion events.

Recent findings by Xu and Carey (1996) indicate that, after seeing two distinct objects (e.g., a duck and a ball) emerge on the opposite sides of a screen, 10-month-olds show no surprise when the screen is removed to reveal one (e.g., a duck) as opposed to two objects (e.g., a duck and a ball). The authors took their results to mean that 10-month-olds are unable to use featural information to individuate objects. The present research examined a different interpretation of the results. This interpretation was based on a distinction between event mapping, in which infants see a sequence of two distinct events and judge whether the two are consistent, and event monitoring, in which infants see a single event and judge whether successive portions of the event are consistent. The present research contrasted infants' performances in event-mapping tasks in which they saw first an occlusion and then a no-occlusion situation (as in Xu & Carey) and in event-monitoring tasks in which they saw only an occlusion situation. It was hypothesized that infants would be more likely to give evidence of correct individuation when tested with the event-monitoring as opposed to the event-mapping tasks. Eight experiments were conducted with infants ages 7.5 to 11.5 months. These experiments yielded two main findings. First, when tested with an event-monitoring task, even 7.5-month-olds give evidence that they can use featural information to individuate the objects involved in an occlusion event. Second, when tested with an event-mapping task, even 9.5-month-olds give evidence that they can use featural information to interpret an occlusion event as long as the event is made extremely simple. These findings give weight to the distinction between event mapping and monitoring and more generally begin to shed light on the fundamental processes involved in infants' formation and use of event representations.

Analysis of Variance↗
PubMed1998

Mental-attentional capacity: does cognitive style make a difference?

There is currently no consensus on whether the difference between field-dependent and field-independent subjects on tasks of cognitive abilities result from different mental processing strategies, from true group differences in cognitive ability, or from both. School-age children (N = 239) were tested for field dependence/independence using the Children's Embedded Figures Test and for mental-attentional capacity using the Figural Intersection Task. Multigroup scaling models were used to separate the contributions of style from ability in children's performance on Figural Intersection items. Results show that field-dependent children have greater odds of success than field-independent children in Figural Intersection items when the task's mental-attentional demand is above the child's mental attentional capacity, as assessed in the same task. The contrary is true when the task's mental-attentional demand is below or equal to the mental-attentional capacity of the child. Overall, field-dependent children obtain lower estimates of mental-attentional capacity than field-independent children in this task. We discuss the implications of these results for the measurement of mental-attentional capacity and the conceptualization of field dependence/independence.

Adolescent↗
PubMed1998

Eight-and-a-half-month-old infants' reasoning about containment events.

The present research examined whether 8.5-month-old infants take into account the width and compressibility of an object when determining whether it can be inserted into a container. The infants in Experiment 1 saw 2 test events. At the start of each event, a tall container rested on the apparatus floor. Next, the container was hidden by a screen, and a large ball attached to the lower end of a rod was introduced into the apparatus and lowered behind the screen into the container. Finally, the screen was removed to reveal the ball's rod protruding above the container's rim. The only difference between the 2 test events had to do with the width of the containers: in 1 event (large-container event), the container was slightly wider than the ball; in the other event (small-container event), the container was only half as wide as the ball, so that it should have been impossible for the ball to be lowered into it. Infants in a control condition saw identical test events except that a small ball was used that could fit into either the large or the small container. The infants in the experimental condition looked reliably longer at the small- than at the large-container event, whereas those in the control condition tended to look equally at the 2 events. These results suggested that, although the infants never saw the ball and the container simultaneously, they realized that the large ball could fit into the large but not the small container, whereas the small ball could fit into both containers. In Experiment 2, the large ball used in Experiment 1 was replaced with an equally large but compressible ball. The results were negative, suggesting that the infants understood that the large compressible ball could be inserted into either the small or the large container. Finally, Experiment 3 confirmed the results of the experimental condition in Experiment 1, with a slightly different procedure. Together, the present results indicate that, by 8.5 months of age, infants are already capable of sophisticated reasoning about containment events.

Attention↗
PubMed1997

Object segregation in 8-month-old infants.

Two experiments examined 8-month-old infants' use of configural and physical knowledge in segregating three-dimensional adjacent displays. The infants in Experiment I saw two identical yellow octagons standing side by side: in the test events, a hand grasped the right octagon and pulled it to the side. The infants looked reliably longer when the octagons moved apart than when they moved together, suggesting that the infants (a) perceived the octagons as a single unit and hence (b) expected them to move together and were surprised when they did not. The infants in Experiment 2 saw a yellow cylinder and a blue box: a hand grasped the cylinder and pulled it to the side. The infants looked reliably longer when the box moved with the cylinder than when the box remained in place, suggesting that they (a) viewed the cylinder and box as distinct units and thus (b) expected the cylinder to move alone and were surprised when it did not. These results indicate that, by 8 months of age, infants use configural knowledge when organizing adjacent displays: they expect similar parts to belong to the same unit and dissimilar parts to belong to distinct units. Additional results revealed that 8-month-old infants' interpretation of displays is affected not only by configural but also by physical consideration. Thus, infants in Experiment 1 who saw a thin blade lowered between the octagons viewed them as two rather than as one unit. Similarly, infants in Experiment 2 who saw the cylinder lying above instead of on the apparatus floor perceived the cylinder and box as one rather than two units. These results indicate that 8-month-old infants bring to bear their knowledge of impenetrability and support when parsing adjacent displays. Furthermore, when faced with two conflicting interpretations of a display, one suggested by their configural and one by their physical knowledge, infants allow the latter to supersede the former. Together, these findings suggest that, by 8 months of age infants approach to segregation is fundamentally similar to that of adults.

Adult↗
PubMed1994

Calibration-based reasoning about collision events in 11-month-old infants.

Previous research indicates that, when a moving object collides with a stationary object, infants expect the stationary object to be displaced. The present experiment examined whether infants believe that the size of the moving object affects how far the stationary object is displaced. In the experiment, 11-month-old infants sat in front of a horizontal track; to the left of the track was an inclined ramp. A wheeled toy bug rested on the track at the bottom of the ramp. The infants in the midpoint condition were first familiarized with an event in which a medium-sized cylinder rolled down the ramp and hit the bug, causing it to roll to the middle of the track. Next, the infants saw one of two test events. In both events, novel cylinders were introduced, and the bug now rolled to the end of the track. The two test cylinders were identical to the familiarization cylinder in material but not in size: one was larger (large-cylinder event) and one was smaller (small-cylinder event) than the familiarization cylinder. The infants in the endpoint condition saw the same familiarization and test events as the infants in the midpoint condition except that the bug rolled to the end rather than to the middle of the track in the familiarization event. The infants in the midpoint condition looked reliably longer at the small-than at the large-cylinder event, whereas the infants in the endpoint condition tended to look equally at the two events. These results indicated that the infants (a) believed that the size of the cylinder affected the length of the bug's displacement and (b) used the familiarization event to calibrate their predictions about the test events. After watching the bug roll to the middle of the track when hit by the medium cylinder, the infants were surprised to see the bug roll to the end of the track with the small but not the large cylinder. After watching the bug roll to the end of the track when hit by the medium cylinder, however, the infants were not surprised to see the bug do the same with either the small or the large cylinder. Parallel results were obtained with adult subjects. The present findings have implications for research on the nature and development of infants' physical reasoning as well as for assessments of causal reasoning in infancy.

Adult↗
PubMed1993

Body scale and infant grip configurations.

This study examined whether hand/object size ratios define common boundaries to the grip configuration patterns of infants and adults. A group of 5- to 8-month-old infants and a group of adults engaged in a displacement grasping task with inverted cups that varied in size. The findings showed that infant and adult grip configurations varied systematically with object size: More digits were brought into the contact grip configurations with increasing object size. Furthermore, when object size was scaled to hand size, common dimensionless ratios defined the grasping patterns and transitions between grasping patterns in a similar manner for both adults and infants. Consistent with a dynamical view of the development of coordination, the strong role of body scale on the developmental prehensile coordination pattern was observed for a given set of task constraints.

Adult↗
PubMed1993

Intuitions about support in 4.5-month-old infants.

The present experiment examined whether 4.5-month-old infants expect an object to fall when its support is removed. The infants saw two test events: a possible and an impossible event. In the possible event, a hand deposited a box fully on a platform and then withdrew, leaving the box supported by the platform. In the impossible event, the hand deposited the box beyond the platform and then withdrew, leaving the box suspended in mid-air with no apparent source of support. The infants looked reliably longer at the impossible than at the possible event, suggesting that they expected the box to fall in the impossible event and were surprised that it did not. Evidence for this interpretation was provided by the results of two control conditions. In one, the box fell when released by the hand beyond the platform. In the other, the hand retained its grasp on the box throughout the events, thereby providing continuous support for it. The infants in these two conditions tended to look equally at the test events. Together, these results indicate that, like adults, 4.5-month-old infants realize that objects cannot remain stable without support.

Concept Formation↗
PubMed1991

Reasoning about the height and location of a hidden object in 4.5- and 6.5-month-old infants.

The present experiments examined 6.5- and 4.5-month-old infants' ability to represent and to reason about the height and location of a hidden object. In Experiments 1 and 2, the infants were habituated to a screen that rotated back and forth through a 180 degree arc, in the manner of a drawbridge. Following habituation, a box was placed behind the screen, and the infants saw two test events. In one (possible event), the screen rotated until it reached the occluded box; in the other (impossible event), the screen rotated through either the top 80% or the top 50% of the space occupied by the box. The results indicated that (a) the 6.5-month-old infants were surprised when the screen rotated through the top 80%, but not the top 50%, of the box and (b) the 4.5-month-old infants failed to be surprised even when the screen rotated through the top 80% of the box (4.5-month-old infants do show surprise, however, when the screen rotates through the entire (100%) box (Baillargeon, 1987a]. Experiments 3 and 4 tested whether infants would be better at detecting that the screen rotated farther than it should if provided with a second, identical box to the side of the box behind the screen. This second box stood out of the screen's path and so remained visible throughout the test trials. The results indicated that with the second box present (a) the 6.5-month-old infants showed surprise when the screen rotated through the top 50% of the occluded box and (b) the 4.5-month-old infants were surprised when the screen rotated through either the top 80% or the top 50% of the box. The results of Experiment 5 revealed that the improvement in performance brought about by the second box disappeared when this box was no longer in the same fronto-parallel plane as the box behind the screen. Different models are considered to describe the impressive quantitative and qualitative physical reasoning abilities revealed by these findings.

Cognition↗
PubMed1991

Object permanence in young infants: further evidence.

Recent evidence suggests that 4.5- and even 3.5-month-old infants realize that objects continue to exist when hidden. The goal of the present experiments was to obtain converging evidence of object permanence in young infants. Experiments were conducted using paradigms previously used to demonstrate object permanence in 5.5-month-old infants and 6.5-month-old infants. In one experiment, 3.5-month-old infants watched a short or a tall carrot slide along a track. The track's center was hidden by a screen with a large window in its upper half. The short carrot was shorter than the window's lower edge and so did not appear in the window when passing behind the screen; the tall carrot was taller than the window's lower edge and hence should have appeared in the window but did not. The infants looked reliably longer at the tall than at the short carrot event, suggesting that they (a) represented the existence, height, and trajectory of each carrot behind the screen and (b) expected the tall carrot to appear in the screen window and were surprised that it did not. Control trials supported this interpretation. In another experiment, 4.0-month-old infants saw a toy car roll along a track that was partly hidden by a screen. A large toy mouse was placed behind the screen, either on top or in back of the track. The female infants looked reliably longer when the mouse stood on top as opposed to in back of the track, suggesting that they (a) represented the existence and trajectory of the car behind the screen, (b) represented the existence and location of the mouse behind the screen, and (c) were surprised to see the car reappear from behind the screen when the mouse stood in its path. A second experiment supported this interpretation. The results of these experiments provide further evidence that infants aged 3.5 months and older are able to represent and to reason about hidden objects.

Attention↗
PubMed1990

Low-dose sufentanil in major surgery.

The purpose of this study was to assess the efficacy of sufentanil 1 micrograms.kg-1 during N2O-O2 and intermittent isoflurane anaesthesia in major non-cardiac surgery. Thirty-one patients (18 females, 13 males; mean age 47 yr), undergoing cholecystectomy received a 1 microgram.kg-1 bolus of sufentanil before the induction of anaesthesia with thiopentone. On average, three sufentanil increments were administered, to a total (bolus + maintenance) dose of 1.5 micrograms.kg-1. Cardiovascular stability was not achieved in eleven patients who then were given isoflurane. The arterial pressure decreased after sufentanil (P less than 0.05), reaching a nadir (mean 108/65 mmHg, heart rate 63 bpm) at one minute post-incision. Clinically important hypertension or hypotension did not occur in any patient. One patient, receiving beta-blocker therapy, required atropine to control bradycardia. Postoperative respiratory depression did not occur in patients who received less than one micrograms.kg-1.hr-1 with the last increment being given more than 20 minutes before the end of anaesthesia. Slight respiratory depression in the recovery room was reported in one patient, who had received a total of 1.3 micrograms.kg-1.hr-1 of sufentanil, and the last sufentanil increment 24 min before the end of surgery. The most frequently reported side-effects were nausea (35 per cent) and vomiting (23 per cent). Induction, maintenance and recovery from anaesthesia were rated as "good" in 87, 87, and 74 per cent of the cases, respectively, and "satisfactory" in the remainder. We conclude that this technique is valuable to assure good protection of the cardiovascular system without undue respiratory depression during recovery.

Adolescent↗
PubMed1990

Why do young infants fail to search for hidden objects?

Recent evidence indicates that infants as young as 3.5 months of age understand that objects continue to exist when hidden (Baillargeon, 1987a; Baillargeon & DeVos, 1990). Why, then, do infants fail to search for hidden objects until 7 to 8 months of age? The present experiments tested whether 5.5-month-old infants could distinguish between correct and incorrect search actions performed by an experimenter. In Experiment 1, a toy was placed in front of (possible event) or under (impossible event) a clear cover. Next, a screen was slid in front of the objects, hiding them from view. A hand then reached behind the screen and reappeared holding the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they understood that the hand's direct reaching action was sufficient to retrieve the toy when it stood in front of but not under the clear cover. The same results were obtained in a second condition in which a toy was placed in front of (possible event) or behind (impossible event) a barrier. In Experiment 2, a toy was placed under the right (possible event) or the left (impossible event) of two covers. After a screen hid the objects, a hand reached behind the screen's right edge and reappeared first with the right cover and then with the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they realized that the hand's sequence of action was sufficient to retrieve the toy when it stood under the right but not the left cover. A control condition supported this interpretation. Together, the results of Experiments 1 and 2 indicate that by 5.5 months of age, infants not only represent hidden objects, but are able to identify the actions necessary to retrieve these objects. The implications of these findings for a problem solving explanation of young infants' failure to retrieve hidden objects are considered.

Attention↗
PubMed1989

Task constraints and infant grip configurations.

The prehensile grip configurations of infants aged 4 through 8 months were examined as they grasped objects that varied in size and shape. The findings revealed that infants as young as 4 months systematically differentiate grip configurations as a function of the object properties in essentially the same way that 8-month-old infants do. However, the younger 4-month-old infants predominantly used the haptic system in addition to the visual system for information pick-up regarding object properties, whereas 8-month-old infants predominantly used information from the visual system alone to differentiate grip configurations according to the object properties. Infants apparently perceive the same action-relevant information through different emphases of the sensory modes to drive the action system with a similar grip configuration for a given object. It is proposed that the traditional description of an orderly sequence to the development of infant prehension (e.g., Halverson, 1931) is too conservative and inflexible to capture the functionally adaptive prehensile behavior of infants to changing task constraints.

Exploratory Behavior↗