Professor plum is showing the detached style of listening. This type of listener are intellectually not present in a conversation although they are present physically. In the situation described clearly the professor was not listening to what Roberto was saying.
Answer:variable - interval
Explanation: In the this scenario, The humanities instructor is using a variable-interval schedule of reinforcement. The instructor used the word 'surprise' meaning the time and date of the test isn't fixed and the quizzes will come up at unpredictable time intervals. This kind of reinforcement results in a steady response rate as it keeps students on their toes simply due to the fact that they have no idea of when the quizzes are coming up.
An organizational unit broadly corresponding to a city ward or a Spanish “barrio”
