Children Getting Lost: Language, space, and the development of cognitive flexibility in humans

Spatial Re-orientation Human adults re-orient using both spatial and non-spatial cues Young children and animals are limited to spatial cues Hypothesis: Use of non-spatial cues is causally linked to the development of language production abilities Language production ability > Non-spatial reorientation ability

Testing Rats (Cheng, 1996) Foraging task - 3 hidden food locations specified by odors and varying brightness throughout the cage Cage rotated to misalign with rat’s orientation

Testing Rats (Cheng, 1986)

Testing Rats (Cheng 1996) Contrary to expectations, rats relied on the 3D geometry of the cage, but NOT “non-geometric clues” Conclusion: adult rats rely strictly on geometry for reorientation tasks

Hermer and Spelke (1994, 1996) test human reorientation

Adult search resultsChild search results - Adult subjects utilize both geometric and non- geometric clues for reorientation - Children utilize only geometric clues for reorientation

Experiment 1 Designed to determine: At what age children being performing like adults in reorientation tasks Which cognitive mechanism(s) enable adult reorientation abilities

Experiment 1 Prior knowledge: first purpose of this experiment was thus to confirm that children of 3-4 years of age would fail to conjoin geometric and non-geometric information to solve this task to test whether subjects who rely on non- geometric information in this task are truly reorienting using that information (like the rats in previous experiments)

Experiment 1 - Purpose Prove that children aged 3-4 years will fail to use both geometric and non-geometric clues to solve task Prove that older children would combine clues to solve task, similar to human adults and different from young children/adult rats Determine the age at which children use a blue wall as a landmark for direct spatial memory

Experiment 1 - Task 8 males, 8 females between 3-4 years old 10 males, 5 females ages 5-6 Subjects are tested in a rectangular chamber with no windows or sources of noise White noise generator Overhead camera Child gets to choose a toy to search for in this ‘game’

Experiment 1 - Design/Results Design Direct Landmark condition: object hidden behind fabric in a corner, child spun 5 times with eyes covered and told to search for toy Variable: one test uses blue was as a DIRECT clue to the object’s location, an INDIRECT clue for the other test Results: Older subjects tended to search the absolutely correct corner Children searched geometrically appropriate locations

Experiment 1 - Results 3-4 yrs., direct yrs., indirect 3-4 yrs., indirect yrs., direct

Experiment 1 - Discussion Children were strikingly successful at using non-geometric (i.e. the blue wall) information to locate a hidden object in the Direct Landmark task Color is being used in addition to ‘left, right, across from’ etc Prior studies showed children 3-4 years perform like young kids or ADULT RATS Transition occurs during ages 5 to 7

Experiment 1 - Discussion 2 groups of children put in reorientation tasks, blue wall used as a direct cue and indirect clue Children from 3 to 6.5 years of age consistently perceived and remembered the location of the blue wall and used its location to guide their search for the object

Experiment 2 Test for correlation of other skill development with flexible reorientation Dependent variable: reorientation task performance Independent variables: age, nonverbal intelligence, digit span, spatial memory span, reorientation performance in all-white room, comprehension/production of “left-right” and “above/behind” phrases

Methodology 10 boys, 14 girls, mean age 5.8 years Reorientation task:

Language production task

Language comprehension task

Digit/serial visuospatial span task Repeat a number series Visuospatial:

Reorientation task results All white roomOne red wall

Reorientation task results

Experiment 3 Correlation between mind and spoken language To determine if children exhibit a search pattern similar to adult rats Requires a combination of landmark and sense information Subjects also gave language production trials Children ages 6-7 years (paid of course)

Experiment 3 Circle of 9 plastic cups with a dwarf statue as an inherent landmark Child watches object become hidden in cup to landmark’s right Child’s eyes + ears covered, toy AND landmark are moved Children expected to show ability similar to adults rats to confine their search to the cups nearest the landmark

Experiment 3 - Subjects are told: `He [the dwarf] likes to play a game in which you and he go into a room together, a toy is hidden, your eyes and ears are covered, and then you have to find the toy.' - After the toy is moved, the experimenter says, `Where's the toy? Go get it', and recorded the subject's subsequent search

Experiment 3 - Results The subjects did NOT search randomly for the object, and searched in the correct location more often than not The 2 locations on either side of the dwarf after being moved were searched more frequently Subjects learned to confine searches to locations next to the landmark Resembled adults rats who searched for hidden food in proximal regions to a movable landmark array (Biegler and Morris, 1993, 1996)

Experiment 3 - Results Error: not enough information was gained to link language production capabilities in question with several subjects, who did not show an ability to search a location above chance Human adults suggest LR production plays a role in moving object searches

Conclusions Previous experiments (Hermer-Vzquez et al., 1999) have shown that verbal interference impairs reorientation in adults Interference = “verbal shadowing”

Conclusions Verbal abilities may increase speed, efficiency, and combination of other skills

Problems Failure to reproduce correlation between LR production and performance in experiment 3 gives cause for doubt Extremely small sample sizes Failure to clearly account for LR and spatial differences