328
Gerhard von der Emde
object distance, then they should judge spheres to be located further away than
cubes, even if their actual distances were identical. Behavioral experiments
exactly confirmed this prediction. The fishes made mistakes when discriminating
between a sphere and a cube. They fell victim to an electrical illusion, which led
them to misjudge the distance of the sphere (von der Emde eta!. 1998).
The use of the slope/amplitude ratio constitutes a newly found mechanism of
depth perception by animals. It enables electric fish to measure object distance
with a single and stationary receptor surface. This mechanism is unique because
all other mechanisms discovered so far employ either two receptor surfaces (e.g.
the two retinae of our eyes) or movement of a single receptor surface. The
mechanism is also unknown in human technology and could provide new
solutions for distance determination by human-made sensors.
References
Bell CC (1990) Mormyromast electroreceptor organs and their afferent fibers in
mormyrid fish. III. Physiological differences between two morphological types
of fibers. J Neurophysiol63: 319-332
Bullock TH, Bodznick DA, Northcutt RG (1983) The phylogenetic distribution of
electroreception: Evidence for convergent evolution of a primitive vertebrate
sense modality. Brain Res Rev 6: 25-46
Caputi AA, Budelli R, Grant K, Bell CC (1998) The electric image in weakly
electric fish: Physical images of resistive objects in Gnathonemus petersii. J
Exp Biol201: 2115-2128
Heiligenberg W (1973) Electro location of objects in the electric fish Eigenmannia
(Rhamphichthyidae, Gymnotoidei). J Comp Physiol 87: 137-164
Heiligenberg W (1991) Neural Nets in Electric Fish. MIT Press, Cambridge,
London
Hopkins CD (1999) Design features for electric communication. J Exp Bioi 202:
1217-1228
Kalmijn AJ (1974) The detection of electric fields from inanimate and animate
sources other than electric organs. In: Fessard A ( ed) Handbook of Sensory
Physiology. Springer Verlag, Berlin, pp 148-200
Lissmann HW, Machin KE (1958) The mechanism of object location in
Gymnarchus niloticus and similar fish. J Exp Bioi 35: 451-486
Meyer JH (1982) Behavioral responses of weakly electric fish to complex
impedances. J Comp Physiol 145: 459-470
Moller P (1995) Electric Fishes. History and Behavior. Chapman & Hall, London
New JG (1997) The evolution of vertebrate electrosensory systems. Brain Behav
Evol 50: 244-252
Pals N, Peters C, Schoenhage AAC (1982) Local geo-electric fields at the bottom
of the sea and their relevance for electrosensitive fish. Netherlands J Zoo! 32:
479-494
Gerhard von der Emde
object distance, then they should judge spheres to be located further away than
cubes, even if their actual distances were identical. Behavioral experiments
exactly confirmed this prediction. The fishes made mistakes when discriminating
between a sphere and a cube. They fell victim to an electrical illusion, which led
them to misjudge the distance of the sphere (von der Emde eta!. 1998).
The use of the slope/amplitude ratio constitutes a newly found mechanism of
depth perception by animals. It enables electric fish to measure object distance
with a single and stationary receptor surface. This mechanism is unique because
all other mechanisms discovered so far employ either two receptor surfaces (e.g.
the two retinae of our eyes) or movement of a single receptor surface. The
mechanism is also unknown in human technology and could provide new
solutions for distance determination by human-made sensors.
References
Bell CC (1990) Mormyromast electroreceptor organs and their afferent fibers in
mormyrid fish. III. Physiological differences between two morphological types
of fibers. J Neurophysiol63: 319-332
Bullock TH, Bodznick DA, Northcutt RG (1983) The phylogenetic distribution of
electroreception: Evidence for convergent evolution of a primitive vertebrate
sense modality. Brain Res Rev 6: 25-46
Caputi AA, Budelli R, Grant K, Bell CC (1998) The electric image in weakly
electric fish: Physical images of resistive objects in Gnathonemus petersii. J
Exp Biol201: 2115-2128
Heiligenberg W (1973) Electro location of objects in the electric fish Eigenmannia
(Rhamphichthyidae, Gymnotoidei). J Comp Physiol 87: 137-164
Heiligenberg W (1991) Neural Nets in Electric Fish. MIT Press, Cambridge,
London
Hopkins CD (1999) Design features for electric communication. J Exp Bioi 202:
1217-1228
Kalmijn AJ (1974) The detection of electric fields from inanimate and animate
sources other than electric organs. In: Fessard A ( ed) Handbook of Sensory
Physiology. Springer Verlag, Berlin, pp 148-200
Lissmann HW, Machin KE (1958) The mechanism of object location in
Gymnarchus niloticus and similar fish. J Exp Bioi 35: 451-486
Meyer JH (1982) Behavioral responses of weakly electric fish to complex
impedances. J Comp Physiol 145: 459-470
Moller P (1995) Electric Fishes. History and Behavior. Chapman & Hall, London
New JG (1997) The evolution of vertebrate electrosensory systems. Brain Behav
Evol 50: 244-252
Pals N, Peters C, Schoenhage AAC (1982) Local geo-electric fields at the bottom
of the sea and their relevance for electrosensitive fish. Netherlands J Zoo! 32:
479-494