Learning in an insect herbivore: How rewards affect color and odor discrimination in a hungry locust. Dr. Martin S. Shapiro California State University,

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Learning in an insect herbivore: Learning in an insect herbivore: How rewards affect color and odor How rewards affect color and odor discrimination in a hungry locust.discrimination in a hungry locust.

• Dr. Martin S. ShapiroCalifornia State University, Fresno

• Dr. Spencer BehmerOxford University

• Corlisa BeltOxford University

MollusksMollusks

HoneybeesHoneybees

Schistocerca gregariaSchistocerca gregaria

Two-sided Y-mazeTwo-Sided Y-MazeTwo-Sided Y-Maze

EnclosureEnclosure

Experiment 1Experiment 1

• Color discrimination: Yellow and Green.• Amount of reward: 3 mg vs. 12 mg wheat grass.

• Nine choices: Equated experience with both options.

• Measured: Choice and response Latency.• n = 12

Enter Time

Choice of Green

Approach Time

Exit Time

Forced Exposure

Choice of Yellow

CHOICECHOICE

0

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1 2 3 4 5 6 7 8 9

CHOICE RUNS

PR

OP

OR

TIO

N O

F C

OR

RE

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C

HO

ICE

CHOICECHOICE

0

0.1

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CHOICE RUNS

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F C

OO

RE

CT

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ICE

Enter Time

0

0.5

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CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

0

0.5

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1 2 3 4 5 6 7 8 9

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Approach Time

Exit Time

0

0.5

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1.5

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1 2 3 4 5 6 7 8 9

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Experiment 2Experiment 2

• Odor Discrimination: Peppermint and Lemon.• Amount of reward: 3 mg vs. 12 mg. • Nine choices: Equated experience with both options.

• Reversed: Rewards reversed for each option for an additional 9 choice runs (18 choices in total).

• n = 12

Odor ArmOdor Arm

CHOICE

0

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CHOICE RUNS

PR

OP

OR

TIO

N O

F C

OR

RE

CT

C

HO

ICE

CHOICE

0

0.1

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CHOICE RUNS

PR

OP

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TIO

N O

F C

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CT

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HO

ICE

Enter Time

0

0.5

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1.5

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Approach Time

0

0.5

1

1.5

2

2.5

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Exit Time

0

0.5

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1.5

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3

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Experiment 3Experiment 3

• Odor Discrimination: Peppermint and Lemon.

• Artificial Diet: – 21% protein : 21% carbohydrate – 7% protein : 7% carbohydrate

• Nine choices: Equated Experience with both options.

• n = 12

CHOICE

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1 2 3 4 5 6 7 8 9

CHOICE RUNS

PR

OP

OR

TIO

N O

F C

OR

RE

CT

C

HO

ICE

Enter Time

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

Approach Time

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

P = 0.038

Exit Time

0

0.5

1

1.5

2

2.5

3

1 2 3 4 5 6 7 8 9

CHOICE RUNS

ME

AN

LO

G L

AT

EN

CY

(S

EC

.)

POS(+)

NEG(-)

SummarySummary

• Good choice results.

• Good discrimination of color and odor. (odor showed less bias.)

• Approach time was significant in all three experiments. by latency

Continuing work at Cal State FresnoContinuing work at Cal State Fresno

with with Schistocerca americanaSchistocerca americana

Future ExperimentsFuture Experiments

• Delay to Reinforcement.– Self Control.– Risk Sensitivity.– Energy Expenditures.

• Effects of Carbohydrates and Proteins on Learning.– Nutrient-Specific Deprivation.– Risk Sensitivity with variability in specific nutrients.

THANK YOU!!!

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