learning in an insect herbivore: how rewards affect color and odor discrimination in a hungry...
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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
Animals in PsychologyAnimals in Psychology
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
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
CHOICECHOICE
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
OO
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(-)
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
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(-)
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
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 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
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 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
Enter Time
0
0.5
1
1.5
2
2.5
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(-)
Approach Time
0
0.5
1
1.5
2
2.5
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(-)
Exit Time
0
0.5
1
1.5
2
2.5
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.
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