A scientist was studying the effect of leg removal on spiders.
The spider's task was to jump over a small object on the command “Spider,
jump!” The scientist removed the spider's legs 1 at a time and found that the spider easily jumped with 7 or 6 legs, but had progressive difficulty with each sequential removal of a leg. Finally, after removal of all 8 legs, the scientist commanded “Spider, jump!”
in an increasingly loud voice, but the spider's body did not move.
The scientist dutifully marked in his laboratory notebook: “Removal of eighth leg: spider goes deaf.” (The earliest reference I am aware of for this “research” was an episode of “Welcome Back, Kotter,” but it may be even older. For the residents too young to recall, this was a 1970s sitcom most notable for John Travolta's first acting role, 15 years before the movie Pulp Fiction.)
Lesperance MM. The Relationship Between Acute Mastoiditis and Antibiotic Use for Acute Otitis Media in Children—Invited Commentary. Arch Otolaryngol Head Neck Surg. 2008;134(1):49. doi:10.1001/archotol.134.1.49