Which of the following is a participant (subject) variable?

To minimize ECT's potential negative effects on memory, it is

a. usually administered only to the left hemisphere. b. usually administered only to the right hemisphere. c. usually administered alternatively to both hemispheres. d. paired with rational-emotive therapy. e. generally accompanied by memory enhancement procedures.

Carl wasn't always afraid of stoplights, but when he was little he was was kidnapped out of his mother's car while they were stopped at a stoplight. He was recovered within 48 hours. But now, even as an adult, he finds himself avoiding stoplights, and if he can't avoid them, he feels tension mounting. Carl's fear of stoplights is a(n) in the classical conditioning paradigm

a. unconditioned stimulus b. unconditioned response c. conditioned stimulus d. conditioned response