Final answer:
Hard Rock was lobotomized in the poem "Hard Rock Returns to Prison from the Hospital for the Criminal Insane" by Etheridge Knight, which caused a drastic change in his personality and behavior.
Step-by-step explanation:
In the poem "Hard Rock Returns to Prison from the Hospital for the Criminal Insane" by Etheridge Knight, Hard Rock was lobotomized. This procedure, which is a form of psychosurgery, was used to treat various mental disorders and involved severing connections in the brain's prefrontal cortex. Lobotomies were once performed on patients deemed uncontrollably violent or aggressive. After Hard Rock's lobotomy, which is described in a metaphorical and symbolic manner in the poem, the inmates noticed a significant change in his behavior; Hard Rock had been a symbol of rebellion and unyielding spirit, but post-lobotomy, he became docile and subdued, exemplifying the procedure's severe impact on an individual's personality and behavior.