Sources of Flexibility in Human Cognition: Dual Task Studies of

Space and Language

Stephanie Lidd and

Jamie Tauber

Linda Hermer-Vasquez, Elizabeth S. Spelke and Alla S. Katsnelson

Human Navigation Abilities

Two unique features Capable of dead reckoning Great flexibility

Disorientation Can reorient themselves after

disorientation How?

Cheng Experiments (1986)

Tested rats’ abilities to find food after disorientation

Rats went to the correct corner and the geometric equivalent at equally high rates Despite differences in non-geometric cues (e.g.

brightness, pattern, and odor) Conclusion: Rats reorient in accordance

with environment shape (geometric module)

Hermer, Spelke: Orientation Abilities in Children (18-24 Months)

Similar to Cheng’s experiment Searched for hidden object in all

white room, then room with one blue wall Searched both corners equally in all

white room Failed to use non-geometric property

(blue wall) as a way of navigation (like adult rats)

Results for Cheng and Hermer &Spelke

Hermer and Spelke: Adult Disorientation

Conducted same experiment using adults

Adults checked geometrically equivalent corners in white room

Were able to use the blue wall as a way of orienting themselves and finding the object (used non-geometric)

Hermer (1994): Disorientation in Children (3-7 years)

Described position of the object as behind colored wall or to the left or right

Children 4+ were successful in describing the objects position behind the wall

Children 6+ were able to describe the position as ‘left’ or ‘right’ of the wall

Hermer (1997) Spatial Language in Children 5-7 years

Tested children’s abilities to use spatial language

Correlation between spatial language and ability to use non-geometric landmarks to locate objects

Causation Between Spatial Language and Development of Spatial Performance Possibilities

Three possibilities Independent, but developmentally

linked Depend on a common factor Development of spatial language

produces change in spatial relations

Experiment 1

Similar to Cheng’s Experiment White room and room with a blue wall

Tested again in each room with ‘verbal shadowing’: repeating a tape-recorded prose

Non-shadowing conditions had ‘white noise’ playing

Disoriented (spun around) before each trial

Diagram of Chamber Used

Results

Experiment 2A

Visual Experimentation with 3 conditions Rhythmic Verbal: repetition of ‘na’ Rhythmic Non-verbal: tapping out pattern Verbal: Repetition of prose

Computer program showing grids varying numbers of ‘T’s and target ‘L’

Subjects had to determine presence or absence of target ‘L’

Results

Experiment 2B

Like Experiment One, with modified disorientation for last 8 subjects

Results: Non-shadowing subjects produced

higher accuracy in recognition Shadowing subjects showed decline in

accuracy Subjects searched with high

frequencies in correct and geometrically equivalent corners

Experiment 2C

Identical with 2B except with Rhythmic shadowing

Results: Shadowing subjects searched the

correct corner with higher frequency than the rotationally equivalent corner

Higher accuracy than verbal shadowing Non-shadowing produced same,

accurate results

What’s the Difference?

Rhythmic and Verbal were equally distracting, yet rhythmic was more accurate Verbal shadowing may interfere with

geometric and non-geometric combination process or

Combination process independent, but verbal shadowing may interfere with their ability to detect or remember the non-geometric landmark

Experiment 3

Verbally shadowing subjects with a simplified version of tests

Instead of being hidden to the left or right, was hidden on top of the walls

Walls were removed from chamber to remove the geometric cues

Results

Subjects located the object with high accuracy

Landmark-appropriate search was higher in Experiment 3 than in the verbal shadowing conditions of Experiments 1 and 2b

Showed adults used non-geometric cues, despite disorientation

Experiment 4

Like Experiment 3, except the object was placed to the left or right of the wall

If verbal shadowing impairs the encoding of non-geometric information only in reorientation tasks, then both subjects should successfully find the object

If verbal shadowing impairs the conjoining of geometric and non-geometric information then non-shadowing subjects should find the object but shadowing subjects should not.

Results

Conclusions

Spatial memory system found in children and adult rats is present in adult humans

Language plays a role in the conjoining of geometric and non-geometric information