the relationship between geometric shape and slope for the representation of a goal location in...

The Relationship Between Geometric Shape and Slope for the Representation of a Goal Location

in Pigeons (Columba livia)

Daniele NardiBowling Green State University

Platformsurrounded by curtains

Feeder

Arena 50cm

Pigeon

Floor

Platform

20º

Arena

Top view Lateral view

Apparatus

Arena on a flat surface Arena on a slope (20º)

Apparatus

Acquisition

*

Slope-related cues added a considerably salient orienting cue to the geometric shape of the arena

→ The task was significantly easier on a slope

Possible factors: shape of the arena, slope inclination.

*

Experiment 1

Task acquisition

0

2

4

6

8

10

12

14

16

18

FLATCONDITION

SLOPECONDITION

Se

ss

ion

s t

o c

rite

rio

n

Geometry test

Geometry testTraining

UPHILL

DOWNHILL

GoalMirrorImage

NearFar

MirrorImage

NearFar

FL

AT

Geomcorrect

Subjects in the slope condition encoded geometric shape just like subjects in the flat condition. Training on a slope did not prevent learning geometric shape information.

Experiment 1

*

0

20

40

60

80

100

Geometriccorrect

Mirrorimage

Near Far

Pe

rce

nta

ge

of c

ho

ice

s

Training

UPHILL

DOWNHILL

GoalMirrorImage

NearFar

Conflict test

UPHILL

DOWNHILL

Slopecorrect

Geomcorrect

MirrorImage

Conflict test

Pigeons encoded shape geometry but they were primarily relying on a slope-based representation to solve the task.

Possible factors affecting the salience of geometry/slope: slope inclination, arena shape.Two modular output representations in guiding behavior

Cheng & Newcombe, 2005

Experiment 1

*

Other

0

20

40

60

80

100

Geometriccorrect

Mirrorimage

Slopecorrect

Other

Per

cent

age

of c

hoic

es

FL

AT

MirrorImage

NearFar

Geomcorrect

Geometry test

uphill

downhill

uphill

downhill

flat

FLAT CONDITION

N = 5

SLOPE-HORIZONTAL CONDITION

N = 5

SLOPE-VERTICAL CONDITION

N = 5

GEOMTERY + SLOPEExperiment 2

Goal 2: test if the salience of vertical information influences geometric shape learning

GEOMETRY

Experiment 3

Rotation test

Pigeons do not generalize the task to a novel orientation (replication of Kelly & Spetch, 2004)Systematic error to the mirror image corner… Why?

Rotation testThe novel orientation isCOUNTERBALANCED

*

Traininguphill

downhill

uphill

downhill

uphill

downhill

uphill

downhill

Geometric correct

Mirror image

Near Far

Rotation test

0

20

40

60

80

100

Geometriccorrect

Mirror image Near Far

Per

cen

tag

e o

f ch

oic

es

CONCLUSIONS

Salience of slope information- first study showing that birds can locate a goal using a slope gradient- redundant multimodal sensory activations- implications against the primacy of geometry for navigation- implications against view-based strategy for solving geometric tasks

Lack of cue competition between slope and geometric learning- many indications of an independent learning of geometry from feature cues- here geometry is not overshadowed by a cue that is more salient- new evidence in support of the “geometric module”

Interactions between two spatial cues can go beyond overshadowing and can produce unexpected effects – lack of generalization.

Study of associative learning applied to spatial memory should not be confined to the “usual” spatial cues.