9. Echolocation in Dolphins
391
TABLE 9.1. Probe targets used in Hammer and Au experiments
General Discrimination
Probe No.
1
2
3
4
5
6
7
8
Composition
AI
CPN
AL
CPN
AL
CRK
AL
PVC
Wall (em)
0048
solid
solid
solid
0.64
solid
solid
0.79
00 (em)
6.35
6.35
3.81
4.06
11.43
11.43
7.62
7.62
Wall Thickness Discrimination
3.81-cm 00 aluminum
7.62-cm 00 aluminum
Probe No.
1
2
3
4
5
6
7
8
Wall (em)
0.32
0048
0.79
0.95
0.32
0.69
1.29
7.62
Material Composition Discrimination
3.81-cm OD/0.32-cm wall
7.62-cm OD/OAO-cm wall
Probe No.
1
2
3
4
5
6
Composition
bronze
glass
steel
bronze
glass
steel
AI, aluminum; CPN, corprene; CRK, coral rock; PVC, poly vinyl chloride; 00, outer
diameter.
experiments are described in Table 9.1. The first experiment involved a
general discrimination in which two solid aluminum cylinders with the same
diameters as the two standard (hollow) aluminum cylinders, two hollow aluminum of different diameter and wall thickness than the aluminum standards, one coral rock with a larger diameter than either coral rock
standards, one PVC tube and two corprene (cork-neoprene) cylinders were
used as probe targets. Initially the dolphin classified three of the aluminum
probes with the standard aluminum targets but eventually classified all of
the probes with all other targets as being "not A." In other words, the
dolphin became a null detector and searched for the presence or absence
of the aluminum standards.
In the second experiment, we investigated the dolphin's ability to discriminate wall thickness. Hollow aluminum probe targets with the same
outer diameter but different wall thickness from the aluminum standards
were used. The results showed that the dolphin could reliably discriminate
wall thickness differences of 0.16cm for the 3.81-cm outer diameter cylinders and 0.32cm for the 7.62-cm outer diameter cylinder. However, a thickness difference threshold was not determined.
In·the third experiment, we investigated the dolphin's ability to discriminate material composition using bronze, glass, and stainless steel probe
cylinders that had the same dimensions as the aluminum standards. The
dolphin mistook the small bronze and steel cylinders for an aluminum standard 25% and 12.5% of the time, respectively. The glass cylinders were mistaken for the aluminum standards 100% and 87.5 % of the time for the small
and large cylinders, respectively.
391
TABLE 9.1. Probe targets used in Hammer and Au experiments
General Discrimination
Probe No.
1
2
3
4
5
6
7
8
Composition
AI
CPN
AL
CPN
AL
CRK
AL
PVC
Wall (em)
0048
solid
solid
solid
0.64
solid
solid
0.79
00 (em)
6.35
6.35
3.81
4.06
11.43
11.43
7.62
7.62
Wall Thickness Discrimination
3.81-cm 00 aluminum
7.62-cm 00 aluminum
Probe No.
1
2
3
4
5
6
7
8
Wall (em)
0.32
0048
0.79
0.95
0.32
0.69
1.29
7.62
Material Composition Discrimination
3.81-cm OD/0.32-cm wall
7.62-cm OD/OAO-cm wall
Probe No.
1
2
3
4
5
6
Composition
bronze
glass
steel
bronze
glass
steel
AI, aluminum; CPN, corprene; CRK, coral rock; PVC, poly vinyl chloride; 00, outer
diameter.
experiments are described in Table 9.1. The first experiment involved a
general discrimination in which two solid aluminum cylinders with the same
diameters as the two standard (hollow) aluminum cylinders, two hollow aluminum of different diameter and wall thickness than the aluminum standards, one coral rock with a larger diameter than either coral rock
standards, one PVC tube and two corprene (cork-neoprene) cylinders were
used as probe targets. Initially the dolphin classified three of the aluminum
probes with the standard aluminum targets but eventually classified all of
the probes with all other targets as being "not A." In other words, the
dolphin became a null detector and searched for the presence or absence
of the aluminum standards.
In the second experiment, we investigated the dolphin's ability to discriminate wall thickness. Hollow aluminum probe targets with the same
outer diameter but different wall thickness from the aluminum standards
were used. The results showed that the dolphin could reliably discriminate
wall thickness differences of 0.16cm for the 3.81-cm outer diameter cylinders and 0.32cm for the 7.62-cm outer diameter cylinder. However, a thickness difference threshold was not determined.
In·the third experiment, we investigated the dolphin's ability to discriminate material composition using bronze, glass, and stainless steel probe
cylinders that had the same dimensions as the aluminum standards. The
dolphin mistook the small bronze and steel cylinders for an aluminum standard 25% and 12.5% of the time, respectively. The glass cylinders were mistaken for the aluminum standards 100% and 87.5 % of the time for the small
and large cylinders, respectively.