Controlling Animals: Carl von Heß, Karl von Frisch, and the Study of Color Vision in Fish

In the 1910s, physiologist Carl von Heß and zoologist Karl von Frisch studied color vision in fish. In what follows, I first show what types of control are involved in their experiments. I then address a rarely discussed issue—the fact that, in these experiments and many others, the animals must be stimulated in order to actively participate. I thus distinguish between two types of control, environmental and behavioral control of activities. Finally, I make a point that goes beyond the problems of experimental control: in studying sensory abilities, it is impossible to directly determine the content of perception. In this sense, these experimental results are, in principle, difficult to control.