LEARNING B Y MARINE INVERTEBRATES
19
sive removal of one and then the other causes fluctuations in the number
of attacks on crabs that certainly seem to support the hypothesis
(Fig. 11). Discrimination experiments, however, give much less clearcut results, with no consistent tendencies to make errors in particular
directions as a result of median superior frontal or vertical lobe removals.
1‘5
20
O
3 1 0
U 01
0
E
E
i
-3L-T’
- 2 0
25
30
n= II
25
3 0
1 0
controls
n =5
7
5
m
p
i
50
y\ALTr;””.
0
0
25
0
5
1 0
I
20
25
30
Trials
Fro. 11. Showing the effect of successive removals of the vertical and median superior
frontal lobes on attacks on crabs by octopuses. There were ten trials per day, in two
groups of five. Operations were done in the evening and the animals first tested next
morning. Controls had dummy operations, the brain being exposed but nothing
removed. (From Young, 1964a.)
It is not a t present clear why discrimination experiments should give
results so different from the “ threshold for attack ” experiments
summarized in Fig. 11, and the possibility must be faced that the
immediate results differ from those shown in relatively long-term
experiments because the system in some way readjusts over a period of
days following brain lesions.
19
sive removal of one and then the other causes fluctuations in the number
of attacks on crabs that certainly seem to support the hypothesis
(Fig. 11). Discrimination experiments, however, give much less clearcut results, with no consistent tendencies to make errors in particular
directions as a result of median superior frontal or vertical lobe removals.
1‘5
20
O
3 1 0
U 01
0
E
E
i
-3L-T’
- 2 0
25
30
n= II
25
3 0
1 0
controls
n =5
7
5
m
p
i
50
y\ALTr;””.
0
0
25
0
5
1 0
I
20
25
30
Trials
Fro. 11. Showing the effect of successive removals of the vertical and median superior
frontal lobes on attacks on crabs by octopuses. There were ten trials per day, in two
groups of five. Operations were done in the evening and the animals first tested next
morning. Controls had dummy operations, the brain being exposed but nothing
removed. (From Young, 1964a.)
It is not a t present clear why discrimination experiments should give
results so different from the “ threshold for attack ” experiments
summarized in Fig. 11, and the possibility must be faced that the
immediate results differ from those shown in relatively long-term
experiments because the system in some way readjusts over a period of
days following brain lesions.