Poster group
Details of individual items:
poster
The aim of this study is to investigate the relationship between two measurements, looking time and visual tracking, for assessing infants' spatial concepts. The common assumption under the looking time measurement is that infants tend to look longer at impossible events. In other words, infants look longer at particular events than others when the outcome of the events violates their expectation so that looking time measurement should somehow be an indicator of infants' prediction. Instead of looking time visual tracking is also commonly used measuring infant's gaze-direction to object disappearance and reappearance. According to Hofstadter & Reznick (1996), gaze-direction measurement suggests greater sensitivity to a change in hiding location than indicated by reaching measures in the delayed response task. Based on this evidence and the assumption of the looking time measurement we hypothesize the following: 'If gaze-direction is different from the hiding place, then infants look longer at the event than in the case where gaze-direction is the same as hiding place.' If the hypothesis is proven in someway we can capture not only the relationship between two measurements but also unify multiple measurements for infant study. In order to verify the hypothesis we are conducting experiments in which both looking time and 'eye-movement' are measured as indicators of infants' expectation. The task used in the experiment was a non-search spatial task. The task is analogous to traditional A not B task, but it differs in the following points:(1) Infants are not required to reach the target, but just allowed to look at the events (non-search task).(2) The position of the hiding place 'rotates' 180 degrees on a turntable so that infants must take into account the rotational movement of the hidden target (rotation task).As in habituation/test paradigm measuring looking time, 6-month-old infants were shown possible or impossible events. In the possible event, a toy was placed one of two wells on a turntable, and two hats was put down to hide each well. After that, the turntable rotated 180 degrees, and the experimenter removed both two hats simultaneously so that the toy reappeared at the opposite position (possible event). In the impossible event the target was reappeared at the same place in spite of the hiding place was rotated 180 degrees. Analysis on overall looking-time shows that there was no significant difference between possible and impossible conditions. This suggests 6-month-olds fail look longer at impossible event in the non-search spatial task. To investigate the effect of gaze-direction on each looking time. We analyzed the looking-time after the point of the target's reappearance. This analysis shows the infants looked longer when their gaze-direction didn't corresponded with the location where the target reappeared. The results suggest that infant's gaze-direction at a critical point affected their looking time. Moreover, the results imply the existence of the infant's expectation or prediction even if they could not notice the impossible event were impossible.
poster
Prior research has concluded that infants are limited toforming egocentric representations of space. Generally, this means thatinfants represent the locations of objects with respect to their own bodiesand not with respect to other objects nor with respect to a fixed coordinatesystem. This conclusion has been based on the findings of experiments thatrequired infants to search for hidden objects. Recently, Kaufman and Needham (1999) conducted an experiment whose aim wasto investigate 6-month-old infants' spatial thinking without requiring theinfants to perform manual or visual search. The general methodology of thisexperiment was as follows: infants habituated to a display that held aconstant location on a corner of a tabletop. Following habituation, infantswere either moved to the opposite side of the table, or they remained in thesame position that they held during the habituation trials. Also, betweenthe habituation trials and the test trial, the display was eithersurreptitiously moved to the diametrically opposite table-corner, or thedisplay remained stationary. The results showed that infants dishabituated when the actual location ofthe display was changed between habituation and test. Furthermore, infantscontinued to habituate when only the egocentric relationship between thedisplay and the infants changed. This pattern of dishabituation wasindicative of objective spatial coding. Another set of studies (Kaufman,1998) found that 4-month-old infants demonstrated similar ability.The experiments presented in this poster were designed to further examinethe findings of Kaufman and Needham (1999) and to reconcile these findingswith those of earlier manual and visual search experiments. In Experiment1, which examined 6-month-old infants, the possible locations of the displaywere separated only laterally, but not in depth (this setup is more similarto those used in the manual and visual search studies). In Experiment 2,the possible locations were separated only in depth, but not laterally.Finally in Experiment 3, which examined 4-month-old infants, the infantsreceived considerably less experience moving about the testing chamberduring the habituation trials than infants in the other experimentsreceived.The results of these studies showed that when the possible locations of thedisplay varied only laterally, infants' performance was analogous toinfants' performance in search experiments. That is, they continued tohabituate to an actual change, but dishabituated to a strictly egocentricchange. The opposite pattern of results was found when the possiblelocations varied only in depth. In this case, infants performed as if theyhad formed and used an objective representation of space. In the thirdexperiment, in which infants did not have as much experience moving todifferent parts of the room during habituation, infants dishabituated to astrictly egocentric change and not to an actual change in the location ofthe display.The results of these experiments help to reconcile the results of Kaufmanand Needham with those of prior studies that required infants to search forobjects. More importantly, they raise interesting questions concerning thenature of infant spatial representations.
poster
The ability to keep track of and estimate locations in space isrequired for many activities, including finding objects and navigatingwithout getting lost. However, little is known about these abilitiesacross the first three years of life. One study (Huttenlocher et al.,1994) used the hierarchical model of spatial coding (Huttenlocher etal., 1991) to examine location estimation in 20-mos-olds in a hiddenobject task. The hierarchical spatial coding model specifies the use ofboth fine-grain and global information to make specific predictionsabout patterns of error bias in location estimation. The present study aimed to replicate previous findings that20-mos-olds were accurate within inches of spatial location estimationand showed no age-related differences in performance (Huttenlocher etal., 1994). A second aim was to test the hypothesis that spatiallocation estimation would improve between 18 and 36 months as a functionof locomotor and cognitive advances. A third aim was to extend thehierarchical spatial coding model (Huttenlocher et al., 1991) to examinewhether error bias in location estimation is affected by spaces thatdiffer in scale (i.e., size, but not shape). A total of 144 children, balanced by gender, will be observed at18, 24, 30, and 36 months of age. Children were randomly assigned tofind a hidden plastic figurine in either a small-scale (91.44cm by 22.86cm) or large-scale (152.4 cm by 40.64 cm) wooden sandbox. Hidinglocations were equally spaced at 15.24 cm apart along the center axis ofeach sandbox. For the small sandbox, children received 10 trials ofrandomly ordered hidings, two at each of five different locations. Inthe large sandbox, children received nine randomly ordered trials, oneeach, at different hiding locations. A decorative pattern, on theoutside edge of the sandbox, was used to measure search accuracy fromlater videotape analysis. Two judges determined Response location(exact search location), directed error response (left or right ofhidden object's location) and mean estimation error (average absolutedistance between search and hidden object's location) from videotape atan average 95% agreement. Preliminary analyses on approximately one-third of the eventualsample revealed that previous findings (Huttenlocher et al., 1994) werepartially replicated. Infants in both studies showed a similarcenter-bias search response pattern, however, the 18- and 24-mo-olds inour sample displayed a greater mean estimation error (M 27.94 cmversus M 5.41 cm for Huttenlocher et al.'s 16- to 24-mo-olds). Aspredicted, mean estimation error decreased systematically over age (M 27.94, 13.335, and 5.639 cm respectively at 18 & 24, 30, and 36 mos,F(3,36) 77.96, p < .001). Finally, a significant effect was revealedfor spatial scale (F(1,36) 30.95, p < .02) with infants showing moresearch accuracy in the small (M 14.122 cm) versus the large sandbox (M 20.472 cm). A significant spatial-scale by age interaction wasrevealed (F(3,36) 23.93, p < .01), showing that the 18- and24-mos-olds had lower mean estimation errors on the small sandbox task.There was no difference in performance for the 30-mos-olds, but the36-mos-olds showed slightly better performance in the large sandboxtask. These findings are among the first to study spatial estimationlocation using the same task across the infancy and toddler periods ofdevelopment. Given that these preliminary analyses are based on asubset of the expected final sample, conclusions will be reserved untildata collection is complete. Final analyses for data collected from thecomplete sample will be presented, and those findings will be discussedin terms of both the applicability of the hierarchical model of spatialcoding for studying early spatial development and developmental trendsin spatial location estimation in the first three years of life.
poster
How do we find our way after becoming disoriented? Previous research (Hermer & Spelke, 1994, 1996; Cheng & Gallistel, 1984) has suggested that children, rats, and adults under dual task conditions use geometric information (e.g., the shape of a room) but not featural information (e.g., the color of a wall). For example, when participants are shown a desired object hidden in one corner of a rectangular room with three white walls and one blue wall, and they subsequently become disoriented, they then search for the object equally in the correct corner and in the geometrically equivalent corner (e.g., short wall to the left of a long wall), rarely searching in the geometrically non-equivalent corners, and failing to use the featural information of the blue wall. Participants in such studies will use the featural information for other tasks that do not require reorienting, demonstrating that they are aware of it and can remember it. Such findings have led researchers to posit that reorienting behaviors rely on a module that receives only geometric information (Hermer & Spelke, 1994, 1996).The current research begins to test an alternative hypothesis, whereby specific visual properties are particularly well suited for driving reorienting; the presence of these properties in geometricinformation, and not a geometric module, explains the prior results. These properties are motivated by computational models of the hippocampus, and produce strong, reliableassociations between sensory representations and an internal sense of orientation. These properties are (a) large and reliable; (b) richly represented in the inputs to the hippocampus; (c) multiple and differentiated; (d) continuously varying; (e) not in competition with other cues. These properties may also be present in featural information, motivating the current studies.Experiment 1 replicated and extended Hermer & Spelke's studies. Sixteen 24-month-olds performed the reorienting task in the blue wall condition in a 9.8' X 6.5' rectangular room. Children used only the room geometry to help them reorient, searching in the correct corner(41% of the time) as often as in the geometrically equivalent corner (45%), and rarely searching in the two geometrically non-equivalent corners (14%). These results demonstrated that children's inability to use featural information to reorient is not an artifact of a very small room (c.f., Newcombe, 1999). Experiment 2 then began our systematic testing of factors that affect children's reorienting. Sixteen 24-month-olds performed the reorienting task in a 9.8' x 6.5' rectangular room with four different colored walls (blue, red, yellow, and white). The four colored walls satisfied two factors: they were both large and reliable and multiple and differentiated. The combination of these factors did not succeed in helping children reorient. Children again used the room's shape to help them find the hidden toy, searching predominantly in the correct corner (47%) and geometrically equivalent corner (34%), and rarely searching in the two geometrically non-equivalent corners (19%). The role of the wall colors, and resulting suggestions for the types of non-geometric cues that should influence reorienting, are discussed.
poster
Inorder to remain oriented in featurless environments adults must keeptrack of their own changes of position within the environment(
poster
Theoverall aim of this research was to establish the youngest age at whichuse of beacons to aid spatial orientation could be demonstrated. Six-and 8.5-month-old infants were tested in a peekaboo paradigm in whichthey had to turn to a target location, either after displacement to anovel position and orientation (Study 1), or to a novel orientationonly (Study 2). A beacon condition where there was a colourfullandmark at the peekaboo location was contrasted with a non-beaconcondition at each age. The 8.5-month-olds showed robust but modestgains in performance in the presence of a beacon, whereas the6-month-old infants did not. A further study (Study 3) confirmed thatperformance was poor at 8.5 months in the absence of a beacon, evenwhen displacements between training and test positions involvedrotations only. This finding is contrary to that reported in earlierliterature (Tyler and McKenzie, 1990). The possibility that onset ofcrawling (at a mean age of 8.5 months) could be linked both to thedevelopment of allocentric and egocentric spatial coding is left openby the relatively later age of competence found in the present seriesof studies.Tyler, D., & McKenzie, B. E. (1990). Spatial updating and trainingeffects in the first year of human infancy. Journal ofExperimental Child Psychology, 50,445-461.
poster
Research in the field of early spatial development has lead to a debate concerning the role of motricity : while some theories (Piaget 1948) assume that motricity is the source of spatial knowledge, others (Mandler 1988/92, L82cuyer 1989/95) assume that perception is the source of this knowledge. Previous studies carried out with normal infants suggest that locomotor activity may be central for the development of spatial cognition. In this study motorically impaired (MI) young children were compared with controls with respect to their spatial search skills in a memory-for-locations task. In this search task hiding containers were rotated 180F8 before search was permitted. There were four groups, each comprising 12 subjects : one group of MI children as the study group and three control groups of healthy children. Twelve children with motor impairment were selected on the basis of following criteria : the presence of a physical deficit that impedes permanently bipedal walking or prevents bipedal walking until 2 years of age, the absence of brain lesions. Children were aged from 1;9 years to 3 years (mean 30 months).The composition of the three control groups was as follows. Children of the first group (hereafter 18-month olds) were aged from 17 months 6 days to 18 months 26 days (mean 17 months 25 days). Children of the second group (hereafter 24-month olds) were aged from 23 months to 25 months (mean 23 months 27 days). Children of the third group (hereafter 30-month olds) were aged from 29 months to 31 months (mean 29 months 25 days).The performance obtained with the physically handicapped group is identical to the one obtained in the healthy control group. Like the control group, the study group searches correctly for a hidden object in the three-positions hiding task. These findings are consistent with predictions from perceptual analytic theories of intelligence. They suggest that motor impairment does not seem to be a major risk factor for developmental delays in complex spatial relations.
poster
Recent research indicates that 7- to 8-month-old infants can detect rulesand transitional probabilities in sequences of auditory stimuli (Saffran,Aslin, & Newport, 1996; Aslin, Saffran, Newport, 1998; Saffran, Johnson,Aslin, & Newport, 1999; Marcus, Vijayan, Rao, & Vishton. 1999). It is notknown whether the mechanism responsible for statistical and rule learningis modality-specific or whether it is a general mechanism capable ofprocessing any type of information. This experiment was designed to testsensitivity to spatial relational information in sequences of visualspatial stimuli in 4-, 8-, and 12-month-old infants. Infants were tested in a modified version of Haith's Visual ExpectationsParadigm (Haith, Hazan, & Goodman, 1988). Each infant was randomlyassigned to one of three conditions. In Condition 1 (p (rep) 0), theprobability of stimulus repetition (i.e., that the stimulus would repeatin the same location as on the previous trial) was zero. That is, thestimulus alternated between two locations on successive trials. InCondition 2 (p (rep) 0.33), the stimulus appeared in a semi-randomfashion, such that the probability was 0.33 that the stimulus would appearin the same location on successive trials. Condition 3 (p (rep) 0.67),consisted of a semi-random sequence where the probability of stimulusrepetition was .67. The stimulus was equally likely to appear in eitherlocation. The direction of the infant's anticipatory shifts following theoffset of the non-informative central cue served as a dependent variable.Each sequence consisted of 60 stimuli and had the following temporalcharacteristics: cue (500 ms) - ISI (1000 ms) - stimulus (1000 ms) - ITI(200 ms).We hypothesized that if infants are sensitive to statistical informationregarding the probability of stimulus repetition, the infant's pattern ofanticipatory shifts will change in comparison with the baseline. Forexample, we expected that in p (rep) 0, the rate of gaze shiftssuggestive of anticipation of stimulus repetition (%AntRepetition) woulddecrease over time, but it would increase in p (rep) .67. Further,infants who detected the rule of alternation in the p (rep) 0, wereexpected to have more correct anticipatory shifts (i.e., % AntAlternation)than would be expected by chance. The results provide no support for the claim that infants in the firstyear of life detect the rule of spatial alternation (see Figure 1). Theeffect of probabilistic structure on the infants' visual anticipatorybehavior is complex (see Figure 2). It appears that 4-month-old infantshave an emergent sensitivity to transitional probabilities in visualspatial sequences. The 8-month-old infants show surprisingly littlevariability in their performance as a function of sequence. Performanceof the 12-month-old infants indicated a basic sensitivity to thestatistical structure of the sequences, but the pattern of results isdifferent from 4-month-olds. The results are discussed in terms ofseveral theoretical accounts on U-shaped developmental functions as wellas the possibility of domain-specificity in transitional probabilitylearning.